Control device

Abstract

The present invention improves the quality of sleep. According to the present invention, a control device comprises a determination unit that determines the sleep stage of a subject on the basis of bioinformation for the subject and a control unit that controls a sleep induction device that comprises a beat generation unit that generates binaural beats. The control unit makes the beat generation unit generate binaural beats that have a frequency of less than 1.0 Hz at least during the sleep stages of the subject.

Description

Technical Field

[0001] The present disclosure relates to a sleep induction device and a control device for controlling the sleep induction device.

Background Art

[0002] Patent Document 1 discloses a technique for generating a series of binaural beats included in a sleep program from a pair of speaker units. The frequencies of the series of binaural beats include, for example, frequencies corresponding to the α, δ, and θ frequency bands.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A control device according to one aspect of the present disclosure includes a determination unit that determines a sleep stage of a subject based on biometric information of the subject, and a control unit that controls a sleep induction device including a beat generation unit that generates binaural beats. The control unit causes the beat generation unit to generate binaural beats having a frequency of less than 1.0 Hz, at least in the sleep stage of the subject.

[0005] A sleep induction device according to one aspect of the present disclosure includes a beat generation unit that generates binaural beats having a frequency of less than 1.0 Hz, at least in the sleep stage.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0007] Hereinafter, the control of binaural beats generated in the brain of a subject according to the present disclosure will be described. Note that when it is described as "A to B" in this specification, it indicates "A or more and B or less".

[0008] 〔Regarding binaural beats〕 Binaural beats refer to sounds having a frequency that is the difference between two frequencies, which are generated in the brain of a subject by making the subject listen to sounds having two different frequencies from the left and right ears. It is known that brain waves synchronize with this difference frequency.

[0009] Based on this finding, the present inventors intensively studied the frequency of binaural beats for efficiently putting a subject to sleep. As a result, the present inventors obtained the finding that the latency to sleep can be shortened by binaural beats having a frequency of less than 1.0 Hz. In addition, the present inventors obtained the finding that the time until reaching the deep sleep stage can be shortened by binaural beats having a frequency of less than 1.0 Hz. Hereinafter, this time will be referred to as the deep sleep latency. In particular, the present inventors obtained the finding that binaural beats having a frequency of 0.2 Hz to 0.3 Hz or less can more effectively shorten the sleep latency or the deep sleep latency. Among them, in particular, the present inventors obtained the finding that binaural beats having a frequency of 0.25 Hz can more effectively shorten the sleep latency or the deep sleep latency.

[0010] Here, generally, the sleep stage can be classified into three stages: wakefulness, REM sleep, and non-REM sleep. Non-REM sleep can be further classified into stage 1 (N1), stage 2 (N2), and stage 3 (N3) in order from the lighter sleep stage. That is, the sleep stage including non-REM sleep can be classified into stages 1, 2, and 3 in order from the lighter sleep stage. REM sleep is sleep accompanied by rapid eye movement (REM). Non-REM sleep is sleep without rapid eye movement. The above deep sleep stage corresponds to stage 3.

[0011] The above classification may be performed based on electroencephalogram data detected by an electroencephalograph worn on a subject. Electroencephalograms are classified into four types in order of increasing wavelength: β waves, α waves, θ waves, and δ waves. β waves are, for example, electroencephalograms with a frequency of about 38 to 14 Hz. α waves are, for example, electroencephalograms with a frequency of about 14 to 8 Hz. θ waves are, for example, electroencephalograms with a frequency of about 8 to 4 Hz. δ waves are, for example, electroencephalograms with a frequency of about 4 to 0.5 Hz.

[0012] When θ waves and δ waves are dominant compared to β waves and α waves, a person is sleeping. Here, "dominant" means that the proportion of a certain wave in the measured electroencephalogram increases. It is known that the dominant electroencephalogram changes periodically within the range of θ waves and δ waves during sleep. Also, when the proportion of θ waves included in the electroencephalogram is less than a predetermined value, a person is in the REM sleep state, and when the proportion of θ waves is equal to or more than the predetermined value and δ waves are dominant, a person is in the non-REM sleep state. Stage 1 is, for example, a state where α waves are 50% or less and various low-amplitude frequencies are mixed. Stage 2 is, for example, a state where irregular low-amplitude θ waves and δ waves appear but there are no high-amplitude slow waves. Stage 3 is, for example, a state where the slow wave is 2 Hz or less and the proportion of slow waves of 75 μV or more is 20% or more. A state where the slow wave is 2 Hz or less and the proportion of slow waves of 75 μV or more is 50% or more may be referred to as Stage 4.

[0013] In addition, as a result of intensive research, the present inventors obtained the following findings. That is, the present inventors found that when a binaural beat having a frequency of less than 1.0 Hz is continuously generated without changing the frequency in order to shorten the sleep latency or deep sleep latency, there is a risk that the sleep efficiency deteriorates, such as occurrence of mid-sleep awakening. Further, the present inventors found that there is also a risk that the sleep efficiency deteriorates when the sound for generating the binaural beat is continuously generated without decreasing its volume. The present inventors found that there is a risk that the sleep efficiency deteriorates when a binaural beat having a frequency of less than 1.0 Hz is continuously generated, or when the sound is continuously generated without decreasing the volume, particularly in the sleep stage of stage 3.

[0014] In addition, the present inventors also obtained a finding that the sleep efficiency tends to improve in a state where the frequency is set to 0 Hz, particularly in a state where the sound for generating the binaural beat is stopped, as compared with the state where the binaural beat is being generated.

[0015] The above-described findings (technical ideas) were newly obtained by the present inventors and are not disclosed or suggested in, for example, Patent Document 1. That is, Patent Document 1 does not disclose or suggest, for example, the setting of the frequency of the binaural beat considered from the viewpoint of shortening the sleep latency or deep sleep latency. Further, Patent Document 1 does not disclose or suggest the setting of the frequency of the binaural beat and the setting of the sound for generating the binaural beat considered from the viewpoint of reducing the deterioration of the sleep efficiency while shortening the sleep latency or deep sleep latency. One aspect of the present disclosure controls the binaural beat to be generated in consideration of the above-described findings. Hereinafter, one embodiment thereof will be described.

[0016] 〔Sleep induction device〕 FIG. 1 is a block diagram showing an example of a schematic configuration of a sleep induction device 1. The sleep induction device 1 is a device that induces a subject into a sleep stage by binaural beats. As shown in FIG. 1, the sleep induction device 1 may include a biological sensor 2, a beat generation unit 3, a control device 4, and a storage device 5. However, the sleep induction device 1 only needs to have at least the beat generation unit 3. In this case, for example, the sleep induction device 1 may be communicably connected to at least one of the biological sensor 2 and the control device 4 provided outside the sleep induction device 1.

[0017] (Biological Sensor) The biological sensor 2 is a sensor that detects biological information of a subject. Examples of the biological information detected by the biological sensor 2 include blood flow information, electrocardiogram information, respiratory information, sweating information, body temperature information, body movement information, and electroencephalogram information. The biological sensor 2 transmits the biological information to the control device 4 for determining the sleep stage of the subject.

[0018] When the biological sensor 2 detects blood flow information, the biological sensor 2 may be a blood flow meter such as a laser Doppler blood flow meter, an ultrasonic blood flow meter, and a pulse wave meter. Examples of the pulse wave meter include a photoelectric pulse wave meter. The blood flow information may include at least one of, for example, blood flow volume, heart rate, heart rate interval, cardiac output, blood flow wave height, and variation coefficient of vasomotion.

[0019] The blood flow volume is the amount of blood flowing through a unit volume of blood vessels per unit time. The heart rate is the number of heartbeats per unit time. The heart rate interval is the interval between heartbeats. The cardiac output is the amount of blood pumped out by one heartbeat of the heart. The blood flow wave height is the difference between the maximum value and the minimum value of the blood flow volume in one heartbeat of the heart. Vasomotion is a spontaneous and rhythmic contraction and relaxation movement of blood vessels. The variation coefficient of vasomotion is a value indicating the variation of the blood flow volume generated based on vasomotion as a variation.

[0020] When the biological sensor 2 detects electrocardiogram information, the biological sensor 2 may be an electrocardiograph. When the biological sensor 2 detects respiratory information, the biological sensor 2 may be sensors such as a microphone and an accelerometer. When using a microphone as the biological sensor 2, the biological sensor 2 can detect information indicating breathing sounds as respiratory information. When using an acceleration sensor as the biological sensor 2, the biological sensor 2 can detect information indicating the movement of the chest as respiratory information.

[0021] When the biological sensor 2 detects sweating information, the biological sensor 2 may be a sweat meter that detects the amount of sweat or weight as sweating information. When the biological sensor 2 detects body temperature information, the biological sensor 2 may be a thermometer such as a thermistor, an infrared sensor, and a mercury thermometer. When the biological sensor 2 detects body movement information, the biological sensor 2 may be an accelerometer or a pressure gauge. When the biological sensor 2 detects electroencephalogram information, the biological sensor 2 may be an electroencephalograph.

[0022] (Control device) The control device 4 may determine the sleep stage of the subject using at least one of the above-described biological information. Therefore, the sleep induction device 1 only needs to include at least one biological sensor 2 capable of detecting the biological information used by the control device 4 for determining the sleep stage.

[0023] The beat generation unit 3 is a device that generates binaural beats. The beat generation unit 3 may be a pair of headphones or a pair of earphones that convert the audio signal received from the control device 4 into sound and output it. The beat generation unit 3 does not have to be a device worn by the subject and may be provided in bedding such as a bed or a pillow. In this case, the beat generation unit 3 only needs to be arranged in the vicinity where the left and right ears are located when the subject lies on the bed.

[0024] The control device 4 may be a device that comprehensively controls each part of the sleep induction device 1. For example, the control device 4 may determine the sleep stage of the subject based on the biological information of the subject detected by the biological sensor 2. Then, the control device 4 may cause the binaural beat generation unit 3 to generate a binaural beat or stop the binaural beat generated by the binaural beat generation unit 3 according to the determined sleep stage of the subject. The control device 4 may include a determination unit 41 and a control unit 42.

[0025] (Determination Unit) The determination unit 41 determines the sleep stage of the subject based on the biological information of the subject. The determination unit 41 transmits the determination result to the control unit 42.

[0026] The determination unit 41 may determine the sleep stage of the subject based on, for example, electroencephalogram information as biological information. As described above, the sleep stage can be determined by electroencephalogram. Further, the determination unit 41 may determine the sleep stage of the subject by using a learned model.

[0027] The learned model is obtained by training a mathematical model that mimics the neurons of the human nervous system so that the sleep stage of the subject can be determined. The mathematical model is a neural network including an input layer, a hidden layer, and an output layer. The mathematical model may be, for example, a convolutional neural network (CNN), a recurrent neural network (RNN), or an LSTM (Long Short Term Memory).

[0028] The learned model may be constructed, for example, by inputting multiple types of teacher data into the mathematical model respectively and updating the weights to minimize the objective function. The teacher data may be data that associates the sleep stage of the subject when the biological information is detected with each of the known multiple types of biological information.

[0029] The determination unit 41 can determine the sleep stage of the subject by inputting the biological information received from the biological sensor 2 into the learned model constructed in this way to the learned model.

[0030] Also, the determination unit 41 may process and use the received biological information. For example, the determination unit 41 may determine the sleep stage of the subject based on the frequency spectrum obtained by performing frequency analysis processing on the biological information. Examples of the biological information include blood flow information. Examples of the frequency analysis processing include Fourier transform processing or wavelet transform processing. The determination unit 41 may also use the learned model in this determination. Also in this case, for example, teacher data may be used to construct the learned model. The teacher data may be data in which the sleep stage of the subject when the biological information was detected is associated with the frequency spectrum obtained by performing frequency analysis processing on each of a plurality of known types of biological information.

[0031] The learned model described above may be generated by a model generation device that generates the learned model, or may be generated by the control device 4.

[0032] (Control unit) The control unit 42 may control the beat generation unit 3. Specifically, the control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 Hz, at least in the sleep stage of the subject.

[0033] For example, the control unit 42 may transmit an audio signal for generating a binaural beat having a frequency of less than 1.0 Hz to the beat generation unit 3 when in the awake state or when it is determined that a transition has occurred from the awake state to the REM sleep state.

[0034] When the control unit 42 transmits an audio signal to the beat generation unit 3, it may select one piece of sound source data from a plurality of types of sound source data stored in the storage device 5, and acquire the selected sound source data from the storage device 5. In this case, it is sufficient that at least one piece of sound source data is stored in the storage device 5. Instead of acquiring the sound source data from the storage device 5, the control unit 42 may acquire the sound source data from an external sound source. In this case, the storage device 5 does not have to store the sound source data.

[0035] The control unit 42 may generate transition data obtained by transitioning the frequency of the acquired sound source data within a range of less than 1.0 Hz. Then, the control unit 42 may transmit the acquired sound source data and the transition data transitioned within a range of less than 1.0 Hz to the beat generation unit 3 as an audio signal. Specifically, the control unit 42 may transmit the acquired sound source data as a first audio signal to one of a pair of headphones or earphones. Also, the control unit 42 may transmit the transition data transitioned within a range of less than 1.0 Hz as a second audio signal to the other of the pair of headphones or earphones. Thereby, the beat generation unit 3 may generate a binaural beat having a frequency of less than 1.0 Hz.

[0036] The sound source data may be a pure tone (a sound of a single frequency). In this case, the control unit 42 may generate a second audio signal (transition data) by varying the frequency of the pure tone within a range of less than 1.0 Hz. Also, the sound source data may be arbitrary music. In this case, the control unit 42 may generate a second audio signal by modulating the frequency of the arbitrary music and varying it within a range of less than 1.0 Hz. Also, the control unit 42 may generate two pieces of transition data obtained by transitioning the frequency of the acquired sound source data so as to be different from each other within a range of less than 1.0 Hz, and use the two pieces of transition data as the first audio signal and the second audio signal, respectively.

[0037] When the sound source data is stereo data, the control unit 42 may extract monaural data from the stereo data. The control unit 42 uses the extracted monaural data as the first audio signal, and may transmit, as the second audio signal, the monaural data (transition data) whose frequency has been transitioned within a range of less than 1.0 Hz, to the beat generation unit 3. Further, the control unit 42 may generate two pieces of transition data whose frequencies of the extracted monaural data are transitioned so as to be different from each other within a range of less than 1.0 Hz, and transmit the two pieces of transition data as the first audio signal and the second audio signal, respectively, to the beat generation unit 3.

[0038] When the sound source data is analog data, the control unit 42 may convert the analog data into digital data. The control unit 42 uses the converted digital data as the first audio signal, and may transmit, as the second audio signal, the digital data (transition data) whose frequency has been transitioned within a range of less than 1.0 Hz, to the beat generation unit 3. Further, the control unit 42 may generate two pieces of transition data whose frequencies of the converted digital data are transitioned so as to be different from each other within a range of less than 1.0 Hz, and transmit the two pieces of transition data as the first audio signal and the second audio signal, respectively, to the beat generation unit 3.

[0039] The control unit 42 may not generate transition data. In this case, the transition data may be stored in advance in the storage device 5 or an external sound source in association with the sound source data. In this case, the control unit 42 may transmit the sound source data and the transition data, or two pieces of transition data generated in advance from the sound source data, as audio signals, to the beat generation unit 3.

[0040] As described above, it has been found that the latency to sleep or the latency to deep sleep can be shortened by binaural beats having a frequency of less than 1.0 Hz. Therefore, by causing the beat generation unit 3 to generate binaural beats having a frequency of less than 1.0 Hz, it becomes possible to shorten the latency to sleep or the latency to deep sleep. Thereby, the quality of sleep can be improved.

[0041] The control unit 42 may cause the beat generator 3 to generate a binaural beat having a frequency of 0.2 to 0.3 Hz. That is, the control unit 42 may transmit an audio signal for generating a binaural beat having a frequency of 0.2 to 0.3 Hz to the beat generator 3. Thereby, the beat generator 3 may generate a binaural beat having a frequency of 0.2 to 0.3 Hz in the beat generator 3.

[0042] As described above, it has been found that the binaural beat having a frequency of 0.2 to 0.3 Hz can effectively shorten the sleep latency or the deep sleep latency. Therefore, by causing the beat generator 3 to generate a binaural beat having a frequency of 0.2 to 0.3 Hz, it becomes possible to effectively shorten the sleep latency or the deep sleep latency.

[0043] (Generation timing of binaural beat) The control unit 42 may cause the beat generator 3 to generate a binaural beat having a frequency of less than 1.0 Hz at least in the sleep onset stage.

[0044] For example, as described above, the control unit 42 may generate the binaural beat in the waking state. That is, the control unit 42 may cause the beat generator 3 to generate the binaural beat before the subject goes to sleep. Also, for example, as described above, the control unit 42 may generate the binaural beat when transitioning from the waking state to the REM sleep state. That is, when the determination unit 41 determines that the sleep stage of the subject is the sleep onset stage, the control unit 42 may cause the beat generator 3 to generate the binaural beat. Also, for example, the control unit 42 may generate the binaural beat in the REM sleep state. The determination unit 41 may determine that the sleep stage of the subject is the sleep onset stage in a state where the subject is transitioning from the waking state to the REM sleep state. This state refers to the state before and after the subject falls asleep. In the following description, the sleep onset stage refers to any stage between before and after falling asleep.

[0045] Thus, the control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 Hz before and after the subject falls asleep. Thereby, the sleep latency or the deep sleep latency can be shortened. In particular, by generating the binaural beat from before the subject goes to sleep, the sleep latency or the deep sleep latency can be effectively shortened.

[0046] Further, the control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 Hz when a predetermined time has arrived. The predetermined time may be set, for example, to the time when the subject wishes to fall asleep. Examples of such a time include 0:00 am. The control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 Hz, for example, when it is determined that the predetermined time set in advance has arrived in a state where the subject is determined to be in a waking state. Thereby, the control unit 42 can generate a binaural beat for shortening the sleep latency or the deep sleep latency, such as generating the binaural beat when the subject is about to fall asleep at the predetermined time, at an effective timing.

[0047] Further, the control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 Hz according to the biological information received from the biological sensor 2. The control unit 42 can determine the activity state of the subject based on the received biological information. Therefore, the control unit 42 can generate the binaural beat at an effective timing based on the activity state of the subject in the sleep stage. The sleep stage refers to before and after the subject falls asleep.

[0048] For example, when the electroencephalogram detected by the electroencephalograph predominantly includes alpha waves, the determination unit 41 can determine that the subject is in a waking state and also determine that the subject is in a resting state. Also, for example, when the blood flow volume detected by the blood flow meter is a predetermined amount, the determination unit 41 can determine that the subject is in a resting state. The predetermined amount is, for example, 70 to 80 mm / 100 g / min. Therefore, the control unit 42 can generate a binaural beat having a frequency of less than 1.0 Hz at an effective timing to shorten the sleep latency or deep sleep latency, for example, when the subject is in a resting state before falling asleep.

[0049] (Change in the frequency of the binaural beat or the volume of the sound) The control unit 42 may change the frequency of the binaural beat generated in the sleep induction stage according to the sleep stage of the subject. As described above, it has been found that if the binaural beat generated in the sleep induction stage is continuously generated without changing the frequency, the sleep efficiency may deteriorate. Therefore, by changing the frequency of the binaural beat according to the sleep stage of the subject, the control unit 42 can reduce the possibility of deterioration of sleep efficiency.

[0050] The timing of changing the frequency of the binaural beat and the amount of change in the frequency may be set, for example, based on experiments, so as to be able to shorten the sleep latency or deep sleep latency and reduce the possibility of deterioration of sleep efficiency.

[0051] For example, the control unit 42 may change the frequency set during binaural beat generation only once. The control unit 42 may change the frequency set during binaural beat generation, for example, when the sleep stage of the subject shifts to another sleep stage. The control unit 42 may change the frequency set during binaural beat generation, for example, when shifting from REM sleep to non-REM sleep. Further, the control unit 42 may change the frequency set during binaural beat generation stepwise over a plurality of times. The control unit 42 may change the frequency set during binaural beat generation, for example, each time the sleep stage of the subject shifts to another sleep stage. Further, the control unit 42 may gradually change the frequency set during binaural beat generation.

[0052] Also, for example, the control unit 42 may generate new transition data by changing the frequency of the most recently generated transition data by a preset amount of change, and transmit the generated transition data to the beat generation unit 3 as the second audio signal. Thereby, the control unit 42 may change the frequency of the binaural beat. Further, the control unit 42 may change the frequency of the binaural beat by changing at least one of the frequencies of two transition data whose frequencies of the sound source data are transitioned to be different from each other in a range of less than 1.0 Hz. The control unit 42 may decrease or increase the frequency of the binaural beat from the frequency of the most recently generated binaural beat.

[0053] Transition data obtained by changing the frequency of transition data whose frequency of sound source data is shifted in a range less than 1.0 Hz may be stored in the storage device 5 or an external sound source in association with the sound source data. Also, among the frequencies of two pieces of transition data whose frequencies of sound source data are shifted so as to be different from each other in a range less than 1.0 Hz, transition data obtained by changing at least one of the frequencies may be stored in the storage device 5 or an external sound source in association with the sound source data. Further, a plurality of pieces of transition data whose frequencies are changed may be stored in the storage device 5 or an external sound source. In this case, the control unit 42 may change the frequency of the binaural beat by acquiring the sound source data and the transition data, or two pieces of transition data, from the storage device 5 or the external sound source and transmitting them as the first audio signal and the second audio signal.

[0054] When the control unit 42 changes the binaural beat according to the sleep stage of the subject, the frequency of the binaural beat may be brought closer to a specific frequency. The value of the specific frequency and the timing of approaching the specific frequency may be set based on, for example, an experiment so as to be able to shorten the sleep latency or the deep sleep latency and reduce the possibility of deterioration of sleep efficiency. The specific frequency may be, for example, 0.2 to 0.3 Hz. The specific frequency may be, for example, 0.25 Hz. Further, the specific frequency may be a value set in association with each sleep stage. By approaching the specific frequency set in this way, the control unit 42 can effectively reduce the possibility of deterioration of sleep efficiency.

[0055] For example, when the determination unit 41 determines that the sleep stage of the subject has transitioned from stage 1 or 2 to stage 3, the control unit 42 may change the frequency of the binaural beat generated in the falling asleep stage. As described above, it has been found that if the binaural beat generated in the falling asleep stage is continuously generated without changing the frequency, particularly in the sleep stage of stage 3, there is a risk of deterioration of sleep efficiency. Therefore, when transitioning to stage 3, the control unit 42 can more effectively reduce the possibility of deterioration of sleep efficiency by changing the frequency of the binaural beat.

[0056] Further, the control unit 42 may reduce the volume of the sound generated by the beat generation unit 3 according to the sleep stage of the subject. Specifically, the control unit 42 may reduce the volume of the sound indicated by each of the first audio signal and the second audio signal according to the sleep stage of the subject. As described above, it has been found that if the sound continues to be generated continuously without reducing the volume, the sleep efficiency may deteriorate. Therefore, by reducing the volume according to the sleep stage, the possibility of deterioration of sleep efficiency can be reduced. The timing of reducing the volume and the amount of reduction of the volume may be set, for example, based on experiments so that the sleep latency or the deep sleep latency can be shortened and the possibility of deterioration of sleep efficiency can be reduced.

[0057] For example, when the determination unit 41 determines that the sleep stage of the subject has changed from stage 1 or 2 to stage 3, the control unit 42 may reduce the volume of the sound generated in the falling asleep stage. As described above, it has been found that if the sound generated to generate the binaural beat in the falling asleep stage is continuously generated without changing the volume, especially in the sleep stage of stage 3, the sleep efficiency may deteriorate. Therefore, when shifting to stage 3, the control unit 42 can more effectively reduce the possibility of deterioration of sleep efficiency by changing the frequency of the binaural beat.

[0058] The control unit 42 may change the frequency of the binaural beat generated in the falling asleep stage to 0 Hz according to the sleep stage of the subject. That is, the control unit 42 may stop the binaural beat according to the sleep stage of the subject. As described above, it has been found that when the frequency is set to 0 Hz, the sleep efficiency tends to improve as compared with the case where the frequency is not changed. Therefore, the control unit 42 can more effectively reduce the possibility of deterioration of sleep efficiency by stopping the binaural beat.

[0059] For example, the control unit 42 may set the frequency of the sound indicated by the first audio signal and the frequency of the sound indicated by the second audio signal to the same value, so that the frequency of the binaural beat is 0 Hz. The frequency of the sound indicated by the first audio signal and the frequency of the sound indicated by the second audio signal may be the same value, for example, set to a value greater than 0 Hz. In this case, the binaural beat is in a stopped state, but the first audio signal and the second audio signal are in a state of being provided to the subject. That is, the sound is provided to the subject.

[0060] It should be noted that the above same value is intended to set the two frequencies so that a significant binaural beat is not generated in the subject's brain, and it is not required to be exactly the same.

[0061] On the other hand, the control unit 42 may set the frequency of the binaural beat to 0 Hz by stopping the first audio signal and the second audio signal. That is, the control unit 42 may stop the output of the sound generated by the beat generation unit 3 in the sleep stage. As described above, when the output of the sound is stopped, it has been found that the sleep efficiency tends to improve compared to the case where the sound is continuously output. Therefore, the control unit 42 can more effectively reduce the possibility of deterioration of sleep efficiency by stopping the output of the sound compared to the case where the binaural beat is stopped while the sound is output.

[0062] For example, when the determination unit 41 determines that the sleep stage of the subject has transitioned from stage 1 or 2 to stage 3, the control unit 42 may stop the output of the sound generated by the beat generation unit 3 in the sleep stage. By stopping the output of the sound in the sleep stage of stage 3, the control unit 42 can more effectively reduce the possibility of deterioration of sleep efficiency.

[0063] The storage device 5 can store the programs and data used by the control device 4. When the determination unit 41 does not use the learned model for determining the sleep stage of the subject, the storage device 5 may store, for example, a table showing the relationship between brain waves and sleep stages. When the determination unit 41 uses the learned model for determining the sleep stage of the subject, the storage device 5 may store the learned model described above. When the control device 4 functions as a model generation device, the storage device 5 may store a mathematical model, a plurality of types of teacher data, and the like. Further, the storage device 5 may store at least one sound source data. Further, the storage device 5 may store at least one transition data in association with the sound source data.

[0064] 〔Flow of processing by the control device〕 FIG. 2 is a flowchart showing an example of the flow of processing by the control device 4. The biological sensor 2 transmits the biological information detected from the subject to the control device 4. Thereby, the control device 4 receives the biological information from the biological sensor 2 (S1). The determination unit 41 may determine the sleep stage of the subject based on the biological information received from the biological sensor 2 (S2).

[0065] The determination unit 41 may determine, for example, whether the subject has transitioned from the awake state to the REM sleep state (S3). When it is determined by the determination unit 41 that the transition to the REM sleep state has occurred (YES in S3), the control unit 42 may cause the beat generation unit 3 to generate a binaural beat having a frequency of less than 1.0 (S4). Thereby, the control unit 42 can cause the beat generation unit 3 to generate the binaural beat in the falling asleep stage.

[0066] When the determination unit 41 determines in the process of S3 that the transition to the REM sleep state has not occurred (NO in S3), the process returns to the process of S1. That is, the control device 4 may execute the processes of S1 and S2 until it is determined by the determination unit 41 that the transition to the REM sleep state has occurred.

[0067] However, the control unit 42 may cause the beat generator 3 to generate a binaural beat having a frequency of less than 1.0, at least during the falling asleep stage. For example, the control unit 42 may cause the binaural beat to be generated by the beat generator 3 when a preset predetermined time arrives, or when it is determined based on the biological information that the subject is in a resting state before falling asleep.

[0068] Also, in this way, when the control unit 42 causes the binaural beat to be generated by the beat generator 3 before the subject goes to sleep, it may start from the process of S4 without executing the processes of S1 to S3. That is, the control unit 42 may first generate the binaural beat in the waking state, and then execute the biological information acquisition process (corresponding to S5 described later) and the sleep stage determination process (corresponding to S6 described later). Thereby, the sleep latency can be effectively shortened. In particular, the arrival time from the waking state to the REM sleep state can be effectively shortened.

[0069] After the process of S4, the control device 4 receives biological information from the biological sensor 2 (S5). Then, the determination unit 41 may determine the sleep stage of the subject based on the biological information received from the biological sensor 2 (S6).

[0070] For example, the determination unit 41 may determine whether the sleep stage of the subject has transitioned from stage 1 or 2 to stage 3 (S7). When it is determined by the determination unit 41 that the transition to stage 3 has occurred (YES in S7), the control unit 42 may stop the binaural beat being generated by the beat generator 3 (S8).

[0071] The control unit 42 may, for example, stop transmitting the first audio signal and the second audio signal to the beat generator 3. In this case, the control unit 42 stops the binaural beat by causing the beat generator 3 to stop outputting sound. Further, the control unit 42 may stop the binaural beat by setting the frequency of the sound included in the first audio signal and the frequency of the sound indicated by the second audio signal to the same value. Thereby, it is possible to reduce the possibility that the sleep efficiency deteriorates due to continuously generating the binaural beat without changing the frequency or volume during the sleep of the subject.

[0072] Further, in S7, the determination unit 41 determines whether to transition from stage 1 or 2 to stage 3. However, for example, it may determine the transition from REM sleep to stage 1 or the transition from stage 1 to stage 2. That is, the control unit 42 may stop the binaural beat according to the sleep stage of the subject.

[0073] Further, the control unit 42 does not necessarily stop the binaural beat in order to reduce the possibility that the sleep efficiency deteriorates. The control unit 42 may change the frequency of the binaural beat or decrease the volume of the sound according to the sleep stage of the subject. Further, the control unit 42 may gradually change the frequency of the binaural beat or gradually decrease the volume of the sound. Particularly in the latter case, after the control unit 42 generates a binaural beat having a frequency of less than 1.0 Hz, the processes of S5 and S6 may not be executed.

[0074] According to the control device 4 of the present embodiment, the sleep latency or the deep sleep latency can be shortened. Thereby, it is possible to contribute to the achievement of Goal 3, "Good health and well-being for all", of the Sustainable Development Goals (SDGs).

[0075] 〔Example〕 In the sleep onset stage, it was verified whether the sleep latency (N2 latency) and the deep sleep latency (N3 latency) can be shortened by causing the subject to listen to a binaural beat having a frequency of 0.2 Hz or more and 0.3 Hz or less, and particularly a frequency of 0.25 Hz.

[0076] In the verification, 12 subjects, 6 females and 6 males, were used. The age of the subjects was 25.3 ± 2.6 years. The BMI (Body Mass Index), the scores of the MEQ (Morningness-Eveningness Questionnaire), and the scores of the PSQI (Pittsburgh Sleep Quality Index) of these 12 subjects are shown below. ·BMI: 21.3 ± 1.8. ·Score of MEQ: 53.1 ± 4.5. ·Score of PSQI: 3.3 ± 1.5.

[0077] In the case of adults, if the BMI is 18.5 or more and less than 25, it is considered to be of normal weight. The score of the MEQ is calculated in the range of 16 to 86 points, and the lower the score, the more morning-type, and the higher the score, the more evening-type it indicates. If the score of the MEQ is 42 points or more and 58 points or less, it is considered to be intermediate type. The score of the PSQI is calculated in the range of 0 to 21 points, and if it is 6 points or more, it is considered that there is a sleep disorder.

[0078] It can be seen that the 12 subjects are of normal weight and have no sleep disorder. Also, 10 of the 12 subjects are of intermediate type and 2 are of morning type. Thus, it can be said that the 12 subjects are healthy. Also, in the extraction of the subjects, a questionnaire regarding the discomfort due to the left-right difference of binaural beats and a test regarding the ability to discriminate the left-right difference of binaural beats were conducted. As a result, the 12 subjects were those who were judged to have no discomfort with binaural beats and to be able to discriminate the left-right difference of binaural beats.

[0079] These 12 subjects were made to wear headphones and take a 90-minute nap under the following 4 conditions. ·Condition 1: Silent state. ·Condition 2: Let a pure tone of 250 Hz be heard in both ears. That is, the frequency of the binaural beat is 0 Hz. ·Condition 3: Let the right ear hear a pure tone of 250.25 Hz and the left ear hear a pure tone of 250 Hz. That is, the frequency of the binaural beat is 0.25 Hz. ·Condition 4: Let the right ear hear a pure tone of 251 Hz and the left ear hear a pure tone of 250 Hz. That is, the frequency of the binaural beat is 1 Hz.

[0080] Figure 3 is a graph showing the verification results. Reference numeral 1001 represents the data of the sleep latency obtained from 12 subjects under each of Conditions 1 to 4. The vertical axis represents the sleep latency, that is, the time (unit: minutes) until reaching Stage 2. Reference numeral 1002 represents the data of the deep sleep latency obtained from 12 subjects under each of Conditions 1 to 4. The vertical axis represents the deep sleep latency, that is, the time (unit: minutes) until reaching Stage 3. These times were determined based on the electroencephalogram data detected by attaching an electroencephalograph to the subject. The circles in each condition represent the data of the sleep latency and the deep sleep latency for each of the 12 subjects.

[0081] As shown in Figure 3, the graphs of each condition are represented using box-and-whisker plots. The box-and-whisker plot extracts the minimum value 101, the first quartile 102, the median 103, the third quartile 104, and the maximum value 105 from the data of the sleep latency or the deep sleep latency obtained from each subject for each condition and graphs them. In this embodiment, the data outside the range of the first quartile - interquartile range × 1.5 and outside the range of the third quartile + interquartile range × 1.5 are specified as outliers 106. The interquartile range is the difference between the third quartile 104 and the first quartile 102.

[0082] By using the box-and-whisker plot, various values such as the above-mentioned maximum value, minimum value, median, etc., and the distribution of the data can be visually recognized. Also, in two box-and-whisker plots, these indicators can be visually compared. Therefore, it becomes possible to make an intuitive judgment as to whether there is a difference in the sleep latency and the deep sleep latency between the two conditions.

[0083] As shown in Fig. 3, it can be visually confirmed that in both the sleep latency and deep sleep latency, the sleep time is shortened when the subject listens to the 0.25 Hz binaural beat of Condition 3 compared to the silent state of Condition 1.

[0084] In addition, statistical verification was performed on whether there were differences in sleep latency and deep sleep latency between Condition 1 and Condition 2, between Condition 1 and Condition 3, between Condition 1 and Condition 4, between Condition 2 and Condition 3, between Condition 2 and Condition 4, and between Condition 3 and Condition 4. Specifically, a significance test was performed for each combination of these two conditions. A significance test is a statistical hypothesis test that sets up a null hypothesis and verifies it. In this example, as the significance test, Wilcoxon signed-rank test, which is an example of a non-parametric test for the significance test between two paired data groups, was used. However, as the significance test, for example, other test methods of non-parametric tests may be used.

[0085] In this example, a null hypothesis that there is no significant difference in sleep variables between the two data groups of conditions was set, and the significance level was set at 5%. In Fig. 3, as a result of performing the Wilcoxon signed-rank test, an asterisk (*) is shown between two conditions where the obtained test statistic was less than the critical value. As shown in Fig. 3, as a result of performing the Wilcoxon signed-rank test, it was statistically confirmed that there was a significant difference in sleep latency and deep sleep latency between the silent state of Condition 1 and the state where the subject listened to the 0.25 Hz binaural beat of Condition 3. Referring to the box-and-whisker plot shown in Fig. 3, it was also found that statistically, the sleep latency and deep sleep latency were significantly shortened when the subject listened to the 0.25 Hz binaural beat of Condition 3 compared to the silent state of Condition 1.

[0086] Thus, it was demonstrated that by having the subject listen to a binaural beat having a frequency of 0.2 Hz or more and 0.3 Hz or less, and in particular 0.25 Hz, in the sleep onset stage, the sleep latency and deep sleep latency can be shortened.

[0087] [Example of Realization by Software] The functions of the control device 4 (hereinafter referred to as "device") are programs for causing a computer to function as the device, and can be realized by programs for causing a computer to function as each control block of the device (particularly, the determination unit 41 and the control unit 42).

[0088] In this case, the above device includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the above program. By executing the above program with this control device and storage device, each function described in each of the above embodiments is realized.

[0089] The above program may be recorded on one or more computer-readable recording media, rather than temporarily. This recording medium may or may not be provided in the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium.

[0090] Also, part or all of the functions of each of the above control blocks can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above control blocks is formed is also included in the scope of the present disclosure. In addition to this, for example, it is also possible to realize the functions of each of the above control blocks by a quantum computer.

[0091] Also, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). That is, each process other than the process of the determination unit 41 may also be executed by AI. In this case, the AI may operate on a control device such as the above-described processor, or may operate on another device (for example, an edge computer or a cloud server, etc.).

[0092] [Supplementary Notes] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to each of the above-described embodiments. That is, various modifications are possible within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, it should be noted that these deformations or modifications are included in the scope of the present disclosure.

Description of Reference Numerals

[0093] 1 Sleep induction device 3 Beat generation unit 4 Control device 41 Determination unit 42 Control unit

Claims

1. A determination unit that determines the sleep stage of the subject based on the biological information of the subject, and a control unit that controls a sleep induction device including a beat generation unit that generates binaural beats, wherein the control unit causes the beat generation unit to generate binaural beats having a frequency of 0.2 Hz or more and 0.3 Hz or less before the subject goes to sleep or when the determination unit determines that the sleep stage of the subject is the falling asleep stage. A control device.

2. The control device according to claim 1, wherein the control unit changes the frequency of the binaural beats so as to decrease or increase from the frequency of the binaural beats generated most recently according to the sleep stage of the subject.

3. The control device according to claim 2, wherein the control unit makes the frequency of the binaural beats approach a specific frequency of 0.25 Hz according to the sleep stage of the subject.

4. The control device according to claim 2, wherein the control unit stops the binaural beats according to the sleep stage of the subject.

5. When the sleep stages in non-REM sleep are set as stage 1, stage 2, and stage 3 in order from the lighter sleep stage, when the determination unit determines that the sleep stage has transitioned from stage 2 to stage 3, the control unit The control device according to claim 1, wherein the frequency of the binaural beats is changed from a frequency of 0.2 Hz or more and 0.3 Hz or less to a frequency of 0.25 Hz, or the volume of the sound generated by the beat generation unit is decreased.

6. The control device according to claim 5, wherein when the determination unit determines that the sleep stage has transitioned from stage 2 to stage 3, the control unit stops the output of the sound from the beat generation unit.

7. The control unit according to claim 1, wherein the control unit causes the binaural beat to be generated by the beat generation unit when it is before the subject goes to sleep and a predetermined time at which the subject desires to fall asleep arrives.

8. The control device according to claim 1, wherein the control unit causes the binaural beat to be generated by the beat generation unit when the biological information indicates that the subject is in a resting state before the subject goes to sleep.

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