Bed cover for supporting a user in transitioning between sleep states

Abstract

A flexible bed cover 200 for covering at least part of a user while they sleep. The bed cover comprises an insulating material 201 and at least one fluid channel 202 arranged below and / or at least partially surrounded by the insulating material. Beneath, or at a base portion of, the fluid channel(s), a lower surface portion 203 is provided for allowing fluid, such as ambient air, to flow up into the fluid channel(s) from beneath the bed cover. At least one fluid driver, such as a fan or impeller, drives fluid through the fluid channel(s) and out of the bed cover. The lower surface portion may comprise a plurality of apertures arranged to receive the ambient air, and the size of the apertures may increase with distance from the fluid driver(s). Data from a temperature or humidity sensor 301a, 301b, or a motion sensor, may be used by a controller to control the fluid driver(s). The controller may determine an amount of heat energy that has been shed by the user over a given time period and may determine whether the user is transitioning from one sleep state to another.

Description

The invention relates to a bed cover for supporting a user in their transition from one sleep state to another. In particular, the present disclosure relates to a bed cover for controlling the flow of fluid within one or more fluid channels within a bed cover to encourage a user to continue their transition towards a desired sleep state. Background While sleeping, a person can be in a number of different sleep states. These sleep states fall broadly into two categories: non-rapid eye movement (NREM); and rapid eye movement (REM). NREM can be divided into three sleep states, known as stages: • Stage 1 • Stage 2 • Stage 3 Stage 1 is the lightest stage of sleep, where the person is just drifting off to sleep. During this stage, the body temperature drops slightly, and muscle activity slows down. In stage 2, the person is in a slightly deeper sleep than in stage 1. Brain waves slow down even further, and the body continues to relax. Body temperature drops further, and heart rate and breathing rate also slow down. Stage 3 is the deepest stage of NREM sleep, also known as slow-wave sleep or deep sleep. During this stage, the brain produces slow delta waves, and it becomes more difficult to wake the person up. Body temperature drops even further, and blood pressure and heart rate decrease significantly. This is the stage where the body undergoes most of its restorative processes, including the release of growth hormone and the repair and regeneration of tissues. REM sleep, on the other hand, is a stage of sleep where the brain becomes more active, and dreams occur. During this stage, body temperature regulation becomes less effective, and the body may actually become slightly warmer. Breathing and heart rate become more irregular, and muscle activity is temporarily paralyzed. This stage is important for cognitive functioning and emotional regulation. Known systems for managing sleep may include the use of wearable devices to determine physiological parameters of a sleeping person. However, such systems are intrusive and can interrupt sleep. In some known systems, a sleep environment may be created within a volume surrounding the sleeping person, which is known as ‘tenting’. In these systems, the environment provided by the volume may be controlled to force a sleeping person into a particular sleep state. However, these systems lose the feeling of comfort a person gets from being in bed. In addition, forcing a sleeping person into new sleep states can be detrimental to sleep. In other known systems, the temperature of a user whilst they sleep may be controlled by controlling the temperature of a mat that is placed on a mattress, with the user sleeping on top of the mat. The temperature of the mat may be controlled based on a sleep history of the user, the local weather, temperature preferences and determined sleep states. Whilst this may allow for some thermoregulation of the user, such systems tend to be inefficient, as there is a limited contact surface area through which temperature control can be affected. Such systems can also feel uncomfortable to the user, with heating or cooling being localised to a specific area, resulting in an unpleasant ‘chill’ sensation. Summary According to the invention in a first aspect, there is provided a flexible bed cover for covering at least part of a user whilst they sleep. The bed cover comprises insulating material and at least one fluid channel arranged below and or at least partially surrounded by the insulating material. The fluid channel provides a channel through which fluid can flow. The bed cover also comprises a lower surface portion arranged beneath the at least one fluid channel or forming a base portion of the fluid channel. The lower surface portion provides a surface through which fluid can flow into the fluid channel from beneath the cover. The bed cover also comprises at least one fluid driver arranged to drive fluid through the at least one fluid channel and out of the bed cover. In an example, the lower surface portion permits ambient air proximal to a user to enter the at least one fluid channel; and the at least one fluid driver is arranged to drive the ambient air out of the at least one fluid channel. The fluid driver may be arranged to drive the ambient air into an environment that is external to the cover. In an example, the lower surface portion comprises a plurality of apertures arranged to receive the ambient air from beneath the bed cover. In an example, the size of the apertures increases with distance from the at least one fluid driver. In an example, the bed cover comprises a plurality of layers. The insulating material forms a first layer. The at least one fluid channel forms a second layer that is arranged beneath the first layer. The lower surface portion forms a third layer that is arranged beneath the second layer. The third layer is arranged relative to the second layer such that the apertures in the third layer align with the at least one fluid channel formed by the second layer. In an example, the bed cover comprises a fourth layer with at least one sensor disposed thereat, the fourth layer being arranged beneath the third layer. In an example, the at least one sensor comprises: (ii) a temperature sensor and / or a (iii) humidity sensor; and the fourth layer is arranged relative to the third layer such that the at least one sensor is at least partially contained within the at least one fluid channel of the second layer. In an example, the bed cover comprises a motion sensor for sensing motion of the bed cover. In an example, the bed cover comprises a vibration sensor for detecting a heartbeat of a user when the user is contact with at least part of the bed cover. In an example, the bed cover comprises a control unit operable to obtain sensor data from the at least one sensor; and the control unit is operable to control the at least one fluid driver based on the obtained sensor data. In an example, the control unit is operable to control at least one of: an on or off status of the at least one fluid driver, a schedule for which the at least one fluid driver is to be switched on or off, and a rate at which the at least one fluid driver is drive fluid through the corresponding respective fluid channel. In an example, the control unit is configured to determine a sleep state for the user based on the obtained sensor data. In an example, the control unit is operable to determine whether a user is transitioning from one sleep state to another based on a comparison of the obtained sensor data with one or more threshold values; and the control unit is configured to control the at least one fluid driver based on the user being identified as transitioning from one sleep state to another. In an example, the control unit is operable to determine an amount of heat energy that has been shed by the user over a given time period, and to determine the sleep state for the user based on the determined amount of heat energy. The determined sleep state may correspond to the user being identified as transitioning from one sleep state to another. In an example, the control unit is operable to obtain fluid driver data from the at least one fluid driver; and the control unit is operable to control the at least one fluid driver based on the obtained fluid driver data. In an example, each layer of the bed cover beneath the at least one fluid channel has a permeability that permits heat and / or moisture in the ambient air beneath the bed cover to enter the at least one fluid channel. In an example, the at least one fluid driver comprises a fan or impeller. In an example, the at least one fluid driver is arranged at a first end of the at least one fluid channel. In an example, the at least one fluid channel extends linearly across at least some of the bed cover. In an example, the bed cover comprises a plurality of fluid channels and a plurality of fluid drivers, wherein each fluid driver is arranged at a respective end of a corresponding fluid channel. In an example, a first fluid driver is configured to drive a first fluid into the cover through a first fluid channel; and a second fluid driver is configured to drive a second fluid out of the cover through a second fluid channel, the first and second fluid drivers being operable to circulate the first and second fluids through the bed cover and into and out of a local sleep environment of the user. In an example, the first and second fluids may be the same fluid or different respective fluids. In an example, the first fluid driver is connected to, or proximal to a source of fluid that is at a cooler temperature than the second fluid. In an example, the first and second fluid drivers are configured to generate directional flow of fluid. In an example, the first and second fluid drivers are configured to drive fluid in opposite directions. In an example, the lower surface portion of the bed cover provides a permeable surface through which fluid driven into the first fluid channel by the first fluid driver is permitted to flow downwards towards a user lying beneath the bed cover. In an example, the lower surface portion of the bed cover provides a permeable surface through which fluid from beneath the cover is permitted to be driven upwards into the second fluid channel by the second fluid driver, and out of the bed cover. In an example, each layer of the bed cover beneath the fluid channels is of a higher permeability than the insulating layer. In an example, each fluid channel comprises a fluid driver at a first end; and a second end of the fluid channel is closed such that fluid cannot enter or leave the fluid channel at the closed end. In an example, the permeability of each layer beneath the fluid channels is sufficiently permeable to permit the flow of fluid into and out of the user’s local sleep environment via the fluid channels. In an example the bed cover comprises a duvet or a sleeping bag. Brief description of the drawings Embodiments of the disclosed methods and apparatus will be described in detail below, with reference to the accompanying drawings, in which: Figure 1 shows an example of a conventional bed cover; Figure 2A shows a cross-sectional view of a first arrangement of layers within a bed cover of the present disclosure; Figure 2B shows a cross-sectional view of a second arrangement of layers within a bed cover of the present disclosure; Figure 2C shows a cross-sectional view of a bed cover comprising a plurality of separate fluid channels, in accordance with the present disclosure; Figure 3A shows a cross-sectional view of a bed cover comprising a sensing layer in accordance with the present disclosure; Figure 3B shows a cross-sectional view of a bed cover comprising a lower layer, in accordance with the present disclosure; Figure 3C shows a cross-sectional view of a bed cover comprising two outer layers, in accordance with the present disclosure; Figure 4A shows a perspective view of a bed cover in accordance with the present disclosure; Figure 4B shows an exploded view of a bed cover in accordance with the present disclosure; Figure 4C shows schematically an example of a fluid channel comprising a plurality of apertures, in accordance with the present disclosure; Figure 5 shows schematically an example of an apparatus for controlling the flow of fluid through a fluid channel of the present disclosure; Figure 6A shows an example of a bed cover comprising a push channel and a pull channel, in accordance with present disclosure; Figure 6B shows an example of a bed cover comprising two push channels, in accordance with the present disclosure; and Figure 7 shows an example of a method for controlling one or more fluid drivers in accordance with the present disclosure. Detailed Description Generally, disclosed herein are methods and apparatus for supporting a user’s transition from one sleep state to another. Reference will be first be made to Figure 1, which shows perspective and exploded views of a conventional bed cover 100. The cover 100 may include, for example, a duvet, quilt, comforter, sleeping bag, or the like. The cover 100 is flexible such that a user can draw the cover 100 across at least part of their body whilst sleeping or resting on a given surface, such as a mattress. That is, in use, at least part of the user is beneath the cover. It will be appreciated that whilst the term ‘bed cover’ is used throughout this description, users need not be restricted to using the bed cover 100 in combination with a bed mattress. In the example shown, the bed cover 100 includes an insert cover 102 in which an insert 104 is contained. In the exploded view, the insert cover 102 is shown with an upper layer 102a and lower layer 102b, but it will be appreciated that in some examples, the insert cover 102 may form a single piece with an opening to receive the insert 104. The insert 104 includes an insulting material for retaining heat, such as down feathers, synthetic fibres, wool, cotton, or a combination thereof. The amount of insulating material used may correspond to a desired heat retention level, or a desired tog rating. For example, a winter duvet will usually include more insulating material, or a higher density of insulating material, than a summer duvet. The insert 104 may also include stitching or baffles (not shown) that create pockets or compartments that help hold the insulating material in place. The insert 104 may use a baffle-box construction to improve loft and heat retention of the bed cover 100. The insert cover 102 encapsulates the insert 104 and acts as a protective layer. The insert cover 102 is usually thinner than the insert 104 itself, and may be made from materials such as cotton, linen, silk, microfibres, synthetic fibres, etc. The insert 104 may be secured within the insert cover 102 by any suitable means, such as by stitching or gluing together one or more of the outer edges. Some bed covers 100, such as duvets, include an attachment portion 106. For example, the insert cover 102 may include an opening for receiving the insert 104, with the opening being sealable way of the attachment portion. The attachment portion may include, for example, one or more: zips, poppers, ties, Velcro strips, snap fasteners, grips, hook and loops, buttons, or a combination thereof. In this way, the insert cover 102 may form a removable layer that can be removed and replaced, e.g., for washing and / orchanging an aesthetic. It will be appreciated that, whilst the attachment portion 106 is shown in Figure 1 as being at an edge of the insert cover 102, any number of attachment portions 106 may be arranged at any suitable location of the insert cover 102, so long as the insert 104 is covered and distributed across a large enough area to form a bed cover 100. Alternatively, there may be no attachment means, for example, where the bed cover 100 forms a single piece (e.g., a comforter or a sleeping bag), with the insert 104 being secured within its covering via e.g., stitching or glue along an outer surrounding perimeter edge. Figure 2A shows a cross-sectional view of an example of a bed cover 200 in accordance with the present disclosure. In Figure 2A, the bed cover 200 is shown as comprising insulating material 201, two fluid channels 202 and a lower surface portion 203 that permits fluid to enter the fluid channels 202 from an underside of the bed cover 200. The insulating material 201 is shown as forming a first layer (insulating layer), below which is arranged a second layer, and below which the lower surface portion 203 is formed by a third layer (referred to herein as the ‘further layer’). The flow of fluid into the fluid channels 202 is indicated by the arrows pointing upwards. For clarity, only one of the fluid channels 202 is shown as receiving the fluid but it will be appreciated that both fluid channels 202 may be arranged to receive fluid from beneath the bed cover 200. Additionally, or alternatively, at least one of the fluid channels may be arranged to direct fluid downwards, out of the third layer, towards an underlying user, as will be described further, later. The fluid may comprise ambient air that has been heated by an underlying user. That is, the lower surface portion 203 may be arranged such that ambient air is able to enter the fluid channels 202 passively, e.g., via convection, and not via a separate air blower or air conditioning unit. The lower surface portion 203 will therefore have sufficient permeability for the ambient air to enter the fluid channel. Preferably, the lower surface portion 203 has a relatively high permeability such that heat and moisture in the ambient air can permeate into the fluid channels 202. In some examples, the lower surface portion 203 may comprise a plurality of apertures, as will be described further in relation to Figures 4A - 4C. In Figure 2A, the fluid channels 202 are formed by a separate layer that is sandwiched between the insulating material 201 and the third layer 203. For example, the insulating material 201 may comprise cavities that match the shape and dimension of corresponding fluid channels 202 that are secured within the cavities. The fluid channels 202 themselves include a hollow section through which the fluid can flow. In some examples, the fluid channels 202 may be secured to the insulating material 201 via a suitable bonding agent such as glue or stitching. Additionally, or alternatively, it may be that the insulating material 201 is sufficiently compact to keep the fluid channels 202 in place. Figure 2E3 shows another example of a bed cover 200 in accordance with the present disclosure. The bed cover 200 of Figure 2B differs from that shown in Figure 2A in that the lower surface portion 203 is formed within a base portion of the fluid channel 202. That is, the lower surface portion 203 is not provided by a separate layerthat is arranged beneath the fluid channel 202. Figure 2C shows a further example of a bed cover 200 in accordance with the present disclosure. In Figure 2C, the fluid channels 202 are shown as forming separate, discrete channels that are not joined to form a complete additional layerthat sits between the insulating material 201 and the lower surface portion 203. It will be appreciated that separate distinct fluid channels 202 could also be used in the example shown in Figure 2A. It will be appreciated that whilst two fluid channels 202 are shown in Figures 2A - 2C, this is just exemplary, and the bed cover 200 may comprise more fluid channels 202 than this. Moreover, whilst the fluid channels 202 shown in Figures 2A - 2C are shown as comprising a cylindrical cross-section (or ‘n-shaped’), other shapes may be used, provided that the fluid channel provides a conduit through which fluid can flow. It will also be appreciated that the fluid channels 202 need not sit completely beneath the insulating material 201, as in Figures 2B and 2C. Hence, the fluid channels 202 are said to be below and I or at least partially surrounded by the insulating material 201. Similarly, the lower surface portion 203 may be said to be arranged beneath the fluid channel 202, as in Figure 2A, or may form a base portion of the fluid channel 202, as in Figures 2B and 2C. The bed cover 200 further comprises one or more fluid drivers (or a ‘fluid driving apparatus’) arranged to drive fluid through the fluid channels 202 (not shown in Figures 2A - 2C). The one or more fluid drivers may comprise fans or impellers that are arranged to drive fluid, such as ambient air, out of the fluid channel 202 and into an external surrounding environment. In this way, the fluid driver may produce a cooling effect, such that ambient air heated by the user is circulated out of the bed cover 200. This may be beneficial for ensuring that a user is able to transition to, or continue transitioning to, a desired sleep state. As mentioned previously, as a user transitions to stage 3 of NREM sleep, they will usually lower their core body temperature, e.g., via sweating, creating warm and moist air in their local vicinity. In conventional bed covers, this warm and moist air can become trapped by the insulating material 201, thereby impeding the user in lowering their body temperature, and therefore their transition to a deeper sleep state. By including one or more fluid drivers, this warm air trapped beneath or within the duvet can be expelled, thus supporting the user in lowering their core body temperature and transitioning to a deeper sleep state. In some embodiments, one or more of the fluid drivers may be used to drive a cooler fluid, such as cooler air from an environment external to the bed cover, into the user’s local sleep environment. The fluid drivers comprise or are connected to a power source. Operation of the fluid drivers may be controlled ‘passively’ such they are always switched on (provided there is a sufficient power supply) or are scheduled to switch on for certain periods. Alternatively, operation of the fluid drivers may be ‘reactive’ in that their operation depends on a determined sleep state for a user, such as whether they are identified as transitioning to a deeper sleep state. Figure 3A shows a cross-sectional view of a further example of the bed cover 200 of the present disclosure. In Figure 3A, a fourth layer (sensing layer 300) is shown as being arranged beneath the third layer 203 described previously in relation to Figure 2A. The sensing layer 300 comprises one or more sensors 301a, 301 b for sensing a parameter of the fluid within the at least one fluid channel 202. Generally, the sensors 301a, 301b are disposed, i.e., secured to and / or within the surface of the of the sensing layer 300. The arrangement of sensors and their operation will be discussed further in relation to Figures 4A - 5. Figure 3E3 shows the bed cover 200 of Figure 3A with a fifth layer (lower layer 302) arranged beneath the sensing layer 300. This layer 302 may form an outer layer, with at least a portion thereof being for covering a user whilst they rest or sleep. This layer 302 may have a relatively higher permeability such that heat and moisture in the ambient air beneath it is able to permeate through it and into the fluid channels 202 via the other intervening layers. More generally, the relative difference in permeabilities between the successive layers may be such that air is able to flow up into, and down out of, the fluid channels. Figure 3C shows the bed cover 200 of Figure 3B, with a sixth layer (upper layer 303) arranged above the insulating layer. This layer 303 may form an additional insulating layer, for example. Although shown as separate layers, it will be appreciated that layers 302 and 303 may form respective portions of a single layer that wraps around the other layers located therebetween. In preferred examples, layers 302 and 303 do not completely envelope the other layers, such that at least one edge, such as a bottom edge, of the bed cover 200 is exposed, thereby allowing fluid to be driven out of, and optionally, into, the bed cover 200 via the fluid channels 202. The arrangement shown in Figure 3C may correspond to a bed cover 200, such as duvet. In examples where the bed cover 200 comprises a sleeping bag, it will be appreciated that the layers may wrap around to form a cavity within which a user can insert themselves. Generally, in use, the cover is drawn at least across at least a portion of the user’s body, defining a cavity in which the user rests; this volume may be referred to as the user’s local sleep environment. Figures 4A and 4B show a further example of a bed cover 400 in accordance with the present disclosure. Figure 4A shows a perspective view of the bed cover 400; Figure 4B shows an exploded view of the bed cover 400; and Figure 4C shows an example of one of the layers within the bed cover 400, as will be described further below. In Figures 4A and 4B, the bed cover 400 is shown as comprising a plurality of layers 401 -407. An insulating layer 401 comprising insulating material is shown as a first layer. Beneath this layer, listed from top to bottom, there is provided a cooling layer 402, a further layer 403, a sensing layer 404 and a lower layer 405. Above the insulating layer 401, two additional upper layers 406, 407 are provided. Each of these layers may correspond to the layers of the same name described previously in relation to Figures 2A - 3C. The cooling layer 402 comprises a plurality of fluid channels 408, with each fluid channel 408 being arranged to receive a fluid and provide a channel through which the fluid may be driven. The fluid channels 408 correspond to the fluid channels described previously in relation to Figures 2A - 3C. Generally, a larger number of channels 408, distributed uniformly across the cover 400 will provide better circulation than a smaller number of sparsely distributed channels 408. Preferably, the channels 408 are made from a material that is sufficiently rigid to maintain the channel’s shape whilst having enough flexibility for the cover 400 to conform (at least partially) to the user’s body shape and not impede the user’s comfort whilst sleeping. An example of a material with these properties is a 3D spacer mesh material. It has been found that this type of material is able to support the weight of (or force exerted by) the insulating material, whilst still providing the desired flexibility and resistance to mechanical forces that would otherwise block the fluid channel. In some examples, the 3D spacer mesh material may be covered with a nylon sleeve. The nylon sleeve may comprise a plurality of apertures for allowing the fluid to permeate into the fluid channel, as will be described in relation to Figure 4C. In some examples, the channels 408 may extend linearly across at least part of the cover 400, as shown in Figures 4A and 4E3. The channels 408 may also be spaced apart at regular intervals. In some examples, the channels 408 may extend along the length of the bed cover 400 (i.e., front to back), such that air is expelled away from the user, i.e. away from their feet. In some examples, the fluid channels 408 may form a network of channels through which fluid can be driven. In examples where the bed cover 400 may need to wrap around the user’s body, for example, in the case of a sleeping bag, the channels 408 may be arranged at a front portion of the cover 400, where the front portion is expected to be outward facing during use. That is, when the user is in the sleeping bag, at least a portion of the cover 400 above them will comprise the fluid channels 408. The front portion may be indicated by virtue of having a different appearance and / or texture, for example. In such examples, the channels 408 themselves may be arranged within this portion, such that the front portion can be identified by the presence of the channels 408. It will be appreciated that, in Figure 4B, the cooling layer 402 is shown as a separate layer to the insulating layer 401, but in some examples, the insulating layer 401 and the cooling layer 402 may form a single layer, e.g., cavities within the insulation layer 401 may form the fluid channels 408. The cavities may be walled, as in Figure 2C. The bed cover 400 further comprises one or more fluid drivers 409 for driving the fluid through the one or more channels 408. In Figure 4B, each fluid channel 408 is shown as comprising a fan at one of its ends for driving ambient air out of the corresponding fluid channel. It will be appreciated that in some examples, one or more of the fluid channels 408 may comprise a fan at both ends. As shown in Figure 4B, the fans are small enough such that they fit within the fluid channels 208 without impeding the flow of air out of the fluid channels 208. Fans of this size tend to be quiet when active, and so disturbance to the user will be minimal. In some examples, the control unit may be configured to limit the work rate of the fans to not exceed a threshold level based on a corresponding noise level that is not to be exceeded. As mentioned previously, the purpose of the fluid drivers 409 is to assist the user in shedding heat by accelerating the rate at which ambient air collected within the fluid channels 408 is expelled from the bed cover 400. The temperature and / or moisture of the ambient air in the channel(s) 408 may be indicative of a user’s sweat level, which in turn may be indicative of the user having generated heat as they transition to a deeper sleep state. It may therefore be desirable to regulate the rate at which heat is expelled from the bed cover 400, so that a user remains in or continues moving towards a desired sleep state. The interaction between the fluid drivers 408 and a determined sleep state will be discussed further in relation to Figures 5-7. In Figure 4E3, a further layer 403 is shown beneath the cooling layer 402. This further layer403 comprises a plurality of apertures 410 for allowing fluid proximate to the user to enter the one or more fluid channels 408. The apertures 410 may be arranged such that each fluid channel 408 has, along the length of its underside, a series of breathable inlets for receiving air proximate to the user. It will be appreciated that layers 404 and 405 beneath this further layer 404 will be formed of material(s) with relatively high permeability so that heat and moisture generated by the user can pass into the fluid channels 408 via the apertures 410. This heat and moisture may be transported by the ambient air proximal to the user. In some examples, the size of a given aperture 410 may depend on its distance from a nearest fluid driver 409. An example of this is shown in Figure 4C, which shows a top-down view of a fluid channel 408, with fan 409a at one of its ends and apertures 410 (dashed) located at its base. The size (area) of each aperture 410 increases with distance from the nearest fluid driver 409. For example, in Figure 4B, the largest aperture 410 is located at a far, distal end of the fluid channel 408. It has been found that this arrangement of apertures 410 encourages relatively even airflow throughout the length of the fluid channel 408, which in turn can reduce work required of the fans to achieve effective air circulation. The pressure of the fluid within the fluid channel tends to be highest closest to the fluid driver, so by varying the size of the apertures in this way, a more uniform pressure profile within the fluid channel is achieved. In Figure 4B, the further layer 403 is shown as being formed above a sensing layer 404 at which one or more sensors 411 are disposed. The sensors 411 may be configured to obtain data from which a user’s sleep state can be determined. For example, stage 3 of NREM sleep is usually associated with a drop in core body temperature and / or reduction in muscle activity, so a transition towards this sleep state may be identifiable by detecting changes in the heat generated by the user and I or their movement over time. For example, it may be that, as a user lowers their body temperature, e.g., via sweating, a detectable build-up of heat and moisture within the fluid channels 408 occurs. Accordingly, the one or more sensors 411 may include temperature sensors and / or humidity sensors. The sensors 411 may be positioned at regular intervals along the length of the fluid channels 408 so that the temperature and moisture of the ambient air contained therein can be detected at multiple locations. The purpose of the temperature and humidity sensors is to detect the temperature and humidity of the ambient air within the fluid channel 408, not the user’s body temperature or moisture of the user’s skin or an outer surface of the bed cover 400. A larger number of sensors 411 distributed throughout one or more fluid channels 408 allows for the collection of more data, which in turn, allows for a more accurate estimation of the user’s sleep state. Additionally, or alternatively, the sensors 411 may include one or more motion sensors for detecting movement of the bed cover 400. Movement of the bed cover 400 tends to be indicative of movement of the underlying user. The motion sensors may include, for example, accelerometers, gyroscopes, cyclometers, optical sensors, etc. The motion sensors may also be arranged within the bed cover 400 in the same manner as the temperature and / or humidity sensors. However, unlike the temperature and / or humidity sensors, the motion sensors need not necessarily be located within the fluid channels 408 and so may be arranged differently (e.g., located outside of the apertures 410, at a separate portion of the sensing layer 404, or at a different layer within the bed cover 400). In some examples, the motion sensors may be external to the bed cover 400, for example, a user’s smart watch or mobile phone, or a camera device, may be used to detect motion of the user. The combination of temperature, humidity and motion sensors allows for richer data to be gathered, improving the accuracy with which a user’s sleep state can be determined. In some examples, the one or more sensors 411 are provided with protective mechanical shielding. In some instances, the cover may further comprise seismic or vibrational sensors for detecting a user’s heartbeat. The vibrational data obtained by these sensors may also contribute to determining the user’s sleep state. In the example of Figure 4E3, the sensors 411 are arranged proximal to the apertures 410 such that the superposition of the insulating layer 401, cooling layer 402, further layer 403 and sensing layer 404 results in the sensors 411 being located at least partially within the fluid channel 408. It will be appreciated that this specific arrangement of layers is an illustrative example, and that in other examples, the sensors 411 may be affixed to the walls or base of the fluid channel 408 or provided at the layer directly beneath the fluid channel 408 without a separate further layer 404 providing the apertures 410. Figure 4B further shows a lower layer 405 that is arranged beneath the sensing layer 404 intended to be directly above the user during in use of the bed cover 400. This layer 405 is made of a material with relatively high permeability to allow heat and moisture generated by the user to be absorbed by the bed cover 400. As discussed previously, the bed cover 400 may also comprise one or more outer layers, such as upper layers 406, 407. The one or more upper layers 406, 407 may comprise additional insulating layers. The lower layer 405 may be distinguishable from the one or more upper layers 406, 407 in that at least a portion of the lower layer 405 has a higher permeability than the one or more upper layers 406, 407. The lower layer 405 and one or more upper layers 406, 407 may form a single outer layer that defines a cavity within which the other layers 401,402, 403, 404 are at least partially contained (as described in relation to Figure 3C). In this sense, the lower layer 405 and one or more upper layers 406, 407 may be both considered ‘outer layers’ in that the other layers 401,402, 403, 404 are sandwiched between them. The outer layers may facilitate securing of the other layers together, e.g., by providing surfaces to which the other layers can be stitched or glued. In some examples, one or more of the layers 401,402, 403, 404,405, 406, 407 are removable by way of an attachment portion, such as that described previously in relation to Figure 1. In some examples, it may be that only the one or more upper layers 406, 407 are removable. For example, where the upper layers 406, 407 form an aesthetic function, and a user wishes to change the look and / or feel of the bed cover 400. In some examples, each layer is engaged with its neighbouring layersuch that there is contact between the layers. This contact may be achieved, for example, by stitching or gluing the layers together along the perimeter of the bed cover 400 (or at least two pairs of opposing edges of the bed cover 400). The person skilled in the art will understand that there are numerous ways in which layers of a bed cover can be secured together to form a single item. In some examples, it may be that the bed cover 400 is an insert, that can be placed within an insert cover (not shown). In such a case, it will be appreciated that the insert cover will need to have a lower surface that does not prevent ambient air from being absorbed by lower layer 405. Such an insert cover will also need to leave the edges of the bed cover exposed such that the fluid drivers are still able to drive the fluid out of the respective ends of the fluid channels 409. It will be appreciated that the bed cover 400 shown in Figures 4A and 4B is an illustrative example and that the bed cover 400 of the present disclosure need not be restricted to this precise number of layers. Figure 5 shows schematically an example apparatus for supporting a user’s transition between sleep states. In Figure 5, the same fluid channel 408 is shown as in Figure 4C, but with a plurality of sensors 411 positioned along its length. As described previously, the sensors 411 may include temperature sensors 501, humidity sensors 502 and / or motion sensors 503. The sensors 411 may protrude (radially) inwards, i.e., point towards the centre of the fluid channel 409 when viewed along the length of the ventilation channel. In Figure 5, a control unit 504 is shown as receiving inputs from the sensors 411 and the fluid drivers 409. The control unit 504 may also be configured to generate outputs that are input to the fluid drivers 409. The inputs to the fluid drivers 409 may be used to control whether the fluid drivers 409 are switched on, the duration that they are switched on for, and I or the rate at which they drive fluid through the fluid channels 408 (e.g. speed). In some examples, the bed cover 400 may not comprise the sensors 411. In these examples, control of the fluid drivers 409 may be passive in that control of the fluid drivers 409 does not depend on obtained sensor data. For example, the fluid drivers 409 may be powered by a battery and have a controllable on I off state. In such examples, the control unit 504 may be configured to schedule operation of the one or more fans. The schedule may correspond to a predetermined schedule, such as an ‘average’ sleep schedule that corresponds with when most people transition between different sleep states (e.g., ‘within X minutes the cover being powered on’ which may be inferred as corresponding with when a user is attempting to get some sleep). Alternatively, the predetermined schedule may be selected for the user based on e.g., their age, location, obtained health data, etc. This data may be obtained from e.g., an application running of the user’s device, such as their smartphone, that is able to connect to the control unit 504, for example. In other examples, control of the fluid drivers 409 may be ‘reactive’ in that their control is dependent on obtained sensor data, which in turn, is used to determine whether the user is likely transitioning to a deeper sleep state. These examples are described further below. As mentioned earlier, the amount of heat and moisture generated by a user will vary as the user transitions between different sleep states. For example, as a user approaches stage 3 of NREM sleep, there may be a build-up of excess heat and moisture within the fluid channels 408 as a result of the user having shed heat via sweating as they lower their core body temperature. Given that stage 3 of NREM sleep is associated with restorative processes, such as growth and repair, it may be desirable to encourage a user to continue transitioning towards this sleep state, so that the body is able to benefit from these processes properly. A lack of NREM stage 3 sleep has been linked to a weakening of the immune system and a heightened risk of dementia or chronic illnesses such as cancer. A user’s sleep state may identify whether the user is awake, at a given stage of NREM sleep, in REM sleep or transitioning or likely to transition between any one of these states. The sleep state data may also identify where within a given transition between sleep states the user is likely to be. For example, the closer the user is to stage 3 of NREM sleep, the greater the rate of change in the temperature and I or humidity that may be detected within the fluid channels 408. Different sleep states may be associated with different thresholds of temperature, humidity and I or motion, or different rates of change in one or more these values, which can be mapped to corresponding sleep states. In some examples, the control unit 504 may be configured to process the sensor data and determine a corresponding sleep state of the user. For example, the control unit 504 may correspond to one or more processors located within the bed cover 400, e.g., attached to the sensing layer 404. In other examples, the control unit 504 may be configured to receive the sensor data and provide this to a remote device, i.e., separate from the bed cover 400, which then performs the necessary processing for determining a user’s sleep state. An example of this is shown in Figure 5, which shows the control unit 504 as having a network interface 505 that allows data to be transmitted to a remote device 507, via a communications network 506, for further processing. The data may be transmitted to the remote device 507 via a wireless network such as Wi-Fi, Bluetooth, cellular network, NFC, etc. The remote device 507 could include, for example, a user’s phone or smart-watch, or a more computationally powerful device, such as a remote server. The remote device 507 may provide the results of the analysis to the control unit 504 which uses them to make a control decision, or the remote device 507 may simply provide the control unit 504 with instructions which the control unit 504 then implements. In Figure 5, the control unit 504 is shown as being located within the bed cover 400, but it will be appreciated that the control unit 504 may be external to the bed cover 400. For example, the sensors 411 and I or fan may each be operable to transmit data to an external control unit 504 and respond to instructions received therefrom. In other examples, it may be that there are separate control units 504 for the sensors 411 and fluid drivers 409a, 409b, with each of these control units 504 being connected to an intermediate device, such as remote device 507. The sleep state of the user may be determined by monitoring changes in the temperature, moisture and / or motion data collected by the sensors 411, over time. The rate of change of one or more of these measurements may be compared against threshold values that correspond to a given sleep state or transition between sleep states. For example, if the rate of change of the temperature and I or moisture within a fluid channel 408 exceeds a threshold value, this may be indicative that the user is approaching stage 3 of NREM sleep. The threshold values may be determined empirically or theoretically, for example. In some examples, sleep state data for a user may be determined based on a predetermined relationship between sleep states and changes to core body temperate, with the latter being inferable from a rate at which the user is detected as shedding heat energy. For example, see e.g., Siegel, J. M. (2001). Body temperature and sleep: A thermostatic model of sleep regulation. Nature, 413(6851), 157-161. In additional or alternative examples, it may be that test data is collected from multiple bed cover users, and is supplemented with additional physiological data, such as heart rate, blood pressure, skin surface temperature, eye movement, polysomnographic data, etc. In this way, a model can be built that correlates the temperature and I or moisture of the ambient airwithin the fluid channels 408, as well as movement of the bed cover 400 or user, with corresponding sleep states. This model may be used to map obtained time-series temperature, moisture and I or motion data to corresponding sleep state data. As mentioned previously, the control unit 504 may be configured to obtain data from and transmit data to the fluid drivers 409. The data received from the fluid drivers may include duty cycle data, such as a percentage of time the fans or impellers have been running within a given time period. Additionally, or alternatively, the data may indicate a speed at which the fans or impellers are being driven and / or a number of fans or impellers that are currently active or inactive within the bed cover 400. In some examples, the control unit 504 may not receive this data directly from the fluid drivers 409; instead, this data may be inferred from the most recent instruction(s) sent to the fluid drivers 409 from e.g., the control unit 504. The control unit 504 may be configured to control the fluid drivers 409 based on a determined sleep state of the user. This may involve controlling the duration and / or rate at which fluid is being driven through the fluid channels 408, for example by controlling the duration and / or speed of the fans or impellers. For example, if the user is identified as cycling to yet deeper sleep states, the work rate of the fans may be increased to prevent a build-up of the heat energy that is being released as the user lowers their core body temperature. If, for example, it is determined that a user is transitioning to stage 3 NREM sleep, the control unit 504 may be configured to reduce the work rate of the fans, to allow the user’s natural processes to maintain the user’s body at an optimal temperature for the sleep state transition. The control unit 504 may be configured to control fans on an individual or group basis. For example, the control unit 504 may selectively switch different fans on or off and I or vary the speed and I or direction, depending on a detected temperature and moisture level within a corresponding ventilation channel 408. As mentioned above, the determination of the user’s sleep state may be performed at the control unit 504 or at a separate device 507 that is in communication with the control unit 504. That is, the sensor data and data associated with the fluid drivers 208 may be processed at the control unit 504 or a remote device 507. Figure 6A shows a further example of a bed cover 600 in accordance with the present disclosure. In Figure 6A, the bed cover 600 is shown as comprising a lower layer 601, an insulating layer 602 and at least two fluid channels 603a, 603b fortransporting a fluid into and out of the bed cover 600. The lower layer 601, insulating layer 602 and fluid channels 603a, 603b correspond with the lower surface portion 203, insulating layer 201 and fluid channels 202 described previously in relation to Figures 2A - 2C. The lower layer 601 has a higher permeability than the insulating layer 602 such that the air warmed by the user can be drawn up through the lower layer 601, into at least one of the fluid channels 603a, 603b. Similarly, the higher permeability of the lower layer 601 may also allow air that has been drawn into one of the fluid channels 603a, 603b, to be expelled out of the lower layer 601 of the bed cover 600. As will be appreciated, at least a portion of the fluid channel will have a higher permeability than the insulating layer 602, to ensure that fluid can enter the fluid channel. The arrangement of layers in this way means the heat- and moistureretaining layer is lifted away from the body of the user, thereby increasing the volume of air within the user’s local sleep environment. One of the fluid channels may provide a path through which ambient air in the vicinity of the user is collected and drawn out of the bed cover 600 (a push channel). Another of the channels may provide a path through which cooler air is driven into the bed cover 600 (a pull channel). In this way, the two channels may provide respective paths for circulating air into and out of the bed cover 600. In turn, this allows air to be circulated across the user’s body whilst they sleep. By generating an airflow across the user’s body in this way, a build-up of heat and moisture within the user’s sleep environment is prevented. It will be appreciated that, where present, the additional layers (as described in relation to Figure 4B) will also have sufficient permeability to allow the air to be directed in this manner. Returning to Figure 6A, a first fluid driver 604a is shown as driving a fluid into the cover 600 through a first fluid channel 603a. As described above, the fluid may comprise air, and the air may be driven into the fluid channel 603a and down towards the user, via the lower layer 601. This downward path corresponds to the path of least resistance by virtue of the relative difference in permeabilities between the insulating layer 602 and lower layer 601. In Figure 6A, a second fluid driver 604b is shown as driving fluid out of a second fluid channel 603b. As mentioned above, the second fluid channel 603b may be arranged to receive fluid, such as warm ambient air from beneath the bed cover 600. The relative difference in permeability between the lower layer 602 and insulating layer 601 means that the path of least resistance will be upwards, from the lower layer 601, into the fluid channel 603b. The second fluid channel 603b may be considered a ‘push’ channel in that it provides a path through which air can be pushed out of the bed cover 600 by the corresponding fluid driver 604, away from the user. In this way, the combined operation of the first and second fluid drivers 604a, 604b creates a circulating current of fluid through the bed cover. Preferably, the air drawn into the pull channel 604a is cooler than air expelled from the push channel 604b by virtue of having been sourced from somewhere other than the immediate vicinity of the user. For example, the first channel 604a may be connected to a source of cool air (not shown), such as that produced by an air conditioner. Alternatively, the air may be sourced from the air outside of the cover 600, which may be cooler than the warm air trapped beneath the cover 600. In some examples, the air pulled into the cover 600 may not necessarily be at a lower temperature than the air expelled from the cover 600 but the combined operation of the push and pull channels (or rather, their corresponding fluid drivers) may nevertheless promote cooling of the user by preventing a build-up of warm ambient air. By measuring the temperature and / or moisture of the air circulating into and out of the cover 600, an amount of heat energy removed from the user’s vicinity over a given time period can be determined. This heat energy may correspond to heat energy that the user has dissipated into their local sleeping environment as a result of lowering their core body temperature as they transition to a deeper sleep state. From this, a user’s sleep state, such as whether they are transitioning to a deeper sleep state, can be determined. Returning to Figure 6A, the first fluid driver 604a is shown as drawing air into the first fluid channel 603a (pull channel) at a first end of the fluid channel 603a. The opposite end of the fluid channel 603a may be closed such that air cannot escape and is instead directed downwards via the lower layer 601. Similarly, the second fluid channel 603b (push channel) may also be closed at one end, such that fluid collected by the second fluid channel 603b is driven out of the other end of the fluid channel 603b, corresponding to the end at which the second fluid driver 604b is located. In some examples, the first and second fluid drivers 604a, 604b may be located at the same ends of the corresponding fluid channels 603a, 603b, with the first and second fluid drivers 604a, 604b causing fluid to flow in opposite directions (as shown). In such examples, the push and pull channels may be blocked at the same respective ends. It may be desirable to have the fluid drivers to be located towards a lower edge of the bed cover, such that any noise generated by the fluid drivers is not within the vicinity of the user’s face, and so that warmed fluid is not expelled in that direction. It will be appreciated that, whilst only one push and pull channel is shown in Figure 2A, in some examples, the cover 600 may comprise a plurality of push and I or pull channels. In some examples, the cover 600 may comprise a plurality of push and pull channels distributed uniformly throughout the cover 600, i.e., across its surface. This may be desirable as it will ensure uniform airflow across the user’s body. In some examples, at least one of the fluid channels 603a, 603b may be arranged to receive a liquid or gel coolant (i.e., not just air), and the corresponding fluid driver may be configured to control the rate at which the coolant is driven into or out of the corresponding fluid channel. In such examples, there may be provided an additional reservoir of coolant that is connected to the fluid channel and a motor or pump for directing coolant into and or out of the fluid channel. Figure 6E3 shows a further example of a bed cover 600 in accordance with the present disclosure. The bed cover 600 shown in Figure 6B differs from that shown in Figure 6A in that the fluid drivers 604a, 604b are configured to drive fluid out of their respective fluid channels 603a, 603b. In Figure 6B, two push channels 603a, 603b and two corresponding fluid drivers 604a, 604b are shown, however, in some examples, there may be fewer (e.g. one) or more than this. In one example, there may be one fluid driver, that pushes air out of one or more fluid channels. For example, the fluid channels may form a connected network of channels, with the one or more fluid drivers pushing fluid out of this network. Figure 7 shows an example of a method 700 for supporting a user as they transition between different sleep states. The method 700 enables circulation of fluid within the fluid channels to be regulated in accordance with a determined sleep state of the user. At step 701, sensor data is received from the one or more sensors 411. As described previously, these sensors 411 may include one or more temperature sensors 501, humidity sensors 502, motion sensors 503 and I or vibration sensors. Hence, step 701 may involve receiving one or more measurements of temperature, humidity, motion and / or vibration. The sensors 411 may be arranged as described previously. The temperature and humidity measurements provide an indication of heat energy generated by the user (e.g., via sweating). This data may be collected as time-series data, such that an amount of heat energy generated by the user per unit time can be determined. At step 702, sleep state data indicative of a sleep state of the user is obtained or determined. The sleep state data is determined based on the received sensor data. This sleep state data may be determined in any of the manners described previously. For example, based on detected changes in the temperature and / or humidity of the fluid in the fluid channels 408 and I or changes in detected motion of the bed cover 400 or the user, and / or changes in vibration which may correlate with changes in the user’s heartbeat. As before, the sleep state data may identify whether the user is in the process of transitioning, or ready to transition, from one sleep state to another. In some examples, determining the sleep state of the user may involve determining an amount, or a rate at which the user is generating heat energy. If the amount, or rate, is determined as exceeding a threshold value, this may be indicative of the user transitioning to a deeper sleep state by virtue of lowering their core body temperature. Different sleep states and sleep state transitions may be associated with different thresholds in the amount or rate of heat energy generation. At step 703, the flow of fluid through the one or more fluid channels 408 is controlled based on the obtained sleep state data. This may involve for example, switching one or more fluid drivers 409 on or off, extending or reducing the time for which the fluid drivers 409 are scheduled to be switched on or off, and / or varying the fluid driving rate of the fluid drivers 409. More generally, this may involve regulating the flow of fluid through the fluid channels 408 via operation of the one or more fluid drivers 409. Different determined sleep states may be associated with different fluid driving rates, for example. In some examples (a first mode of operation), responsive to the user being detected as transitioning to, or being ready to transition to, a deeper sleep state, the fluid drivers may be controlled to stop or slow the rate at which fluid is circulated through the bed cover 200, to allow the user to naturally maintain a core body temperature that is optimal forthat sleep state transition. This may correspond to the situation where the user is identified as having shed sufficient heat energy to begin transitioning to a deeper sleep state, such as stage 3 of NREM sleep. In such examples, the fluid driving rate of at least some of the fluid drivers is reduced, to ensure that the air flow generated across the user’s body does not interfere with the user’s ability to transition to the deeper sleep state. The fluid driving rate of the fluid drivers may be increased once it is determined that the user is no longer in the process of transitioning to a deeper sleep state. In these examples, it may be that the fans are active for most of the time that the bed cover is powered on. In some examples (a second mode of operation), responsive to the user being detected as transitioning to, or being ready to transition to, a deeper sleep state, the rate at which fluid is driven through the fluid channels may be increased. For example, the work rate of the fluid drivers may be increased, in anticipation of the user dissipating more heat energy as they lower their core body temperature. Alternatively, or in addition, the number of active fluid drivers may be increased, and I or the duration for which they are scheduled to be active. In such examples, once it is determined that the user has completed or is likely to complete the transition, the fluid driving rate of the one or more fluid drivers is reduced. In some examples, different sleep states may be associated with different fluid driving rates, e.g. the speed, duration and / or number of active fans may be increased in proportion to the amount of heat energy that the user is detected as, or predicted, to generate as they transition to a deeper sleep state. The amount of heat energy generated by the user will correlate with their sleep states and the transitions therebetween. Whether or not the fluid driving rate is increased or decreased may depend on the specific sleep state transition that is determined for the user. In some examples, the user may be able to select which of the first or second modes of operation is used to control the fluid driving rate of the one or more fluid drivers. The method 700 shown in Figure 7 may correspond to the method executed by the control unit 504 described previously, for example. The obtained sleep state data may be used by the control unit 504 to make a control decision with respect to control of the fluid drivers 409. Alternatively, the obtained sleep state data may comprise instructions which themselves have been generated based on sleep state analysis performed at a separate device, such as a connected remote device 507. In some examples, the processing may be distributed between the control unit 307 and the remote device 507. In some examples, the method 700 may further comprise receiving data associated with one or more fluid drivers 409. This data may provide an indication of the operation status of the fluid drivers 409, such as duty cycle data, work rate data, speed data, etc. The obtained sleep state data may be determined based on both the received sensor data and the data associated with the one or more fluid drivers 409. For example, if the work rate of the fans has been increased but there has also been a detectable increase in temperature and I or humidity in the fluid channels, this may be indicative that the user is transitioning to yet a deeper sleep state, or that the user is at risk of no longer transitioning to a deeper sleep state. In some examples, the method 700 may further comprise determining the sleep state data, i.e., rather than simply obtaining it or instructions that have been generated based on the determined sleep state data. For example, the method 700 may comprise determining whether the user is transitioning between sleep states based on a comparison of the sensor data and fluid driver data with one or more threshold values. A computer program may be configured to provide any of the above-described methods. The computer program may be provided on a computer readable medium. The computer program may be a computer program product. The product may comprise a non-transitory computer usable storage medium. The computer program product may have computer-readable program code embodied in the medium configured to perform the method. The computer program product may be configured to cause at least one processor to perform some or all of the method. Various methods and apparatus are described herein with reference to block diagrams or flowchart illustrations of computer-implemented methods, apparatus (systems and / or devices) and / or computer program products. It is understood that a block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and / or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and / or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions / acts specified in the block diagrams and / or flowchart block or blocks, and thereby create means (functionality) and / or structure for implementing the functions / acts specified in the block diagrams and / or flowchart block(s). Computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions / acts specified in the block diagrams and / or flowchart block or blocks. A tangible, non-transitory computer-readable medium may include an electronic, magnetic, optical, electromagnetic, or semiconductor data storage system, apparatus, or device. More specific examples of the computer-readable medium would include the following: a portable computer diskette, a random-access memory (RAM) circuit, a read-only memory (ROM) circuit, an erasable programmable read-only memory (EPROM or Flash memory) circuit, a portable compact disc read-only memory (CD-ROM), and a portable digital video disc readonly memory (DVD / Blu-ray). The computer program instructions may also be loaded onto a computer and / or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer and / or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions / acts specified in the block diagrams and / or flowchart block or blocks. Accordingly, the invention may be embodied in hardware and / or in software (including firmware, resident software, micro-code, etc.) that runs on a processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof. 5 It should also be noted that in some alternate implementations, the functions / acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Moreover, the functionality of a given block of the flowcharts and / or block diagrams may be separated 10 into multiple blocks and / or the functionality of two or more blocks of the flowcharts and / or block diagrams may be at least partially integrated. Finally, other blocks may be added / inserted between the blocks that are illustrated. It will be apparent to those skilled in the art that various modifications and variations can be 15 made to the disclosed systems and methods. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed systems and methods. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

1. A flexible bed cover for covering at least part of a user whilst they sleep, the bed cover comprising:insulating material;at least one fluid channel arranged below and or at least partially surrounded by the insulating material, the fluid channel providing a channel through which fluid can flow;a lower surface portion arranged beneath the at least one fluid channel or forming a base portion of the fluid channel, the lower surface portion providing a surface through which fluid can flow into the fluid channel from beneath the cover; andat least one fluid driver arranged to drive fluid through the at least one fluid channel and out of the bed cover.

2. A bed cover according to claim 1, wherein the lower surface portion permits ambient air proximal to a user to enter the at least one fluid channel; andwherein the at least one fluid driver is arranged to drive the ambient air out of the at least one fluid channel.

3. A bed cover according to any preceding claim, wherein the lower surface portion comprises a plurality of apertures arranged to receive the ambient air.

4. A bed cover according to claim 3, wherein the size of the apertures increases with distance from the at least one fluid driver.

5. A bed cover according to claim 3 or claim 4, wherein the bed cover comprises a plurality of layers, the insulating material forming a first layer;the at least one fluid channel forming a second layer that is arranged beneath the first layer; andthe lower surface portion forming a third layer that is arranged beneath the second layer, the third layer being arranged relative to the second layer such that the apertures in the third layer align with the at least one fluid channel formed by the second layer.

6. A bed cover according to claim 5, further comprising a fourth layer with at least one sensor disposed thereat, the fourth layer being arranged beneath the third layer.

7. A bed cover according to claim 6, wherein the at least one sensor comprises: (ii) a temperature sensor and I or a (iii) humidity sensor; andwherein the fourth layer is arranged relative to the third layer such that the at least one sensor is at least partially contained within the at least one fluid channel of the second layer.

8. A bed cover according to any preceding claim, wherein the bed cover comprises a motion sensor for sensing motion of the bed cover.

9. A bed cover according to any of claims 6 to 8, comprising a control unit operable to obtain sensor data from the at least one sensor; andwherein the control unit is operable to control the at least one fluid driver based on the obtained sensor data.

10. A bed cover according to claim 9, wherein the control unit is operable to determine an amount of heat energy that has been shed by the user over a given time period, and to determine whether the user is transitioning from one sleep state to another.

11. A bed cover according to claim 9 or claim 10, wherein the control unit is operable to obtain fluid driver data from the at least one fluid driver; andwherein the control unit is operable to control the at least one fluid driver based on the obtained fluid driver data.

12. A bed cover according to any of claims 9 to 11, wherein the control unit is operable to determine whether a user is transitioning from one sleep state to another based on a comparison of the obtained sensor data with one or more threshold values; andwherein the control unit is configured to control the at least one fluid driver based on the user being identified as transitioning from one sleep state to another.

13. A bed cover according to any of claims 5 to 12, wherein each layer of the bed cover beneath the at least one fluid channel has a permeability that permits heat and I or moisture in the ambient air beneath the bed cover to enter the at least one fluid channel.

14. A bed cover according to any preceding claim, wherein the at least one fluid driver comprises a fan or impeller.

15. A bed cover according to any preceding claim, wherein the at least one fluid driver is arranged at a first end of the at least one fluid channel.

16. A bed cover according to any preceding claim, wherein the at least one fluid channel extends linearly across at least some of the bed cover.

17. A bed cover according to any preceding claim, comprising a plurality of fluid channels and plurality of fluid drivers, wherein each fluid driver is arranged at a respective end of a corresponding fluid channel.

18. A bed cover according to claim 16, wherein a first fluid driver is configured to drive fluid into the cover through a first fluid channel; andwherein a second fluid driver is configured to drive fluid out of the cover through a second fluid channel, the first and second fluid drivers being operable to circulate fluid into and out of the bed cover.

19. A bed cover according to claim 18, wherein the lower surface portion of the bed cover provides a permeable surface through which fluid driven into the second fluid channel is able to flow downwards towards a user.

20. A bed cover according to any preceding claim, wherein each fluid channel comprises a fluid driver at a first end; anda second end of the fluid channel is closed such that fluid cannot enter or leave the fluid channel at the closed end.

21. A bed cover according to any of claims 1 to 20, wherein the bed cover comprises a duvet.

22. A bed cover according to any of claims 1 to 20, wherein the bed cover comprises a sleeping bag.30

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