Biological cycle prediction system and program

Abstract

In the present invention, a rhythm estimation unit (105), using a prediction formula created based on the phase response curve of a circannual rhythm, estimates the circadian rhythm of a subject from: changes in biological information throughout a day of the subject, measured by a body temperature sensor (101); a light stimulation time, which is the time at which a light stimulation state is determined by a first determination unit (103); and an awakening time, which is the time at which an awakening state is determined by a second determination unit (104), where the estimation is made for the day after the changes in biological information of the subject is measured by a body temperature sensor (101). The rhythm estimation unit (105) outputs the estimated circadian rhythm. The outputted circadian rhythm is displayed on a display unit (107), for example.

Description

Biological cycle prediction system and program

[0001] The present invention relates to a biological cycle prediction system and program.

[0002] As is well known, biological cycles (circadian rhythms) are controlled by the body's endogenous clock mechanism, the internal clock (biological clock, circadian clock).Recent research has revealed that time is closely related to this circadian rhythm, not only to the quality of sleep, exercise, and work, but also to various aspects of life, such as the effectiveness of medications (pharmacology) and the effects of food (nutrition).

[0003] The circadian rhythm is maintained on a roughly 24-hour cycle, but is subject to significant changes (modulation) due to factors such as exposure to light, diet, and exercise in daily life. In healthy individuals, the so-called life rhythms, such as sleep-wake and activity rhythms, are synchronized with the biological cycle.

[0004] On the other hand, for example, shift workers and other shift workers, due to the influence of irregular lifestyle rhythms, their lifestyle rhythms and biological cycles become misaligned (desynchrony), and continued desynchrony increases the risk of impaired physical and mental health (Non-Patent Document 1). Synchronization of lifestyle rhythms and biological cycles is important for a healthy lifestyle. However, because the lifestyle rhythm of shift work cannot be changed, it is important to align biological cycles with the lifestyle rhythm.

[0005] Satoko Hashimoto et al., "Sleep and Biological Rhythms," Japanese Pharmacological Journal, Vol. 129, No. 6, pp. 400-403, 2007. Melissa A. St Hilaire et al., "Human phase response curve to a 1 h pulse of bright white light," The Journal of Physiology, vol. 590, pt. 13, pp. 3035-3045, 2012.

[0006] In order to synchronize the biological cycle with the circadian rhythm, it is important to check daily whether the biological cycle is synchronized or desynchronized with the circadian rhythm. It is also important to predict desynchronization in advance and resolve the desynchronization state as soon as possible (Reference 2). However, there is currently a problem in that it is not possible to quickly synchronize when desynchronization is predicted.

[0007] The present invention has been made to solve the above problems, and has as its object to enable quick synchronization when desynchronization is predicted.

[0008] The biological cycle prediction system of the present invention includes a body temperature sensor that measures core body temperature or heart rate over time as biological information of a subject, an illuminance sensor that measures the brightness of the subject's surroundings over time, a first determination device that determines a light stimulation state when the measurement value of the illuminance sensor exceeds a set value, a second determination device that determines the subject's wakefulness state based on the subject's posture, and a rhythm estimation device that uses a prediction formula created based on the phase response curve of the circannual rhythm to estimate and output the circadian rhythm of the subject for the day after the change in the subject's biological information is measured by the body temperature sensor, from the change in the subject's daily biological information measured by the body temperature sensor, the light stimulation time at which the first determination device determined the light stimulation state, and the wakefulness time at which the second determination device determined the wakefulness state.

[0009] A program according to the present invention is a program for causing a computer to function as the first determination device, the second determination device, and the rhythm estimation device included in the above-described biological cycle prediction system.

[0010] As described above, according to the present invention, the circadian rhythm of a subject on the day after changes in the subject's biological information are measured by a body temperature sensor is estimated from the changes in the subject's biological information over the course of a day measured by a body temperature sensor, the light stimulation time at which the first determination device determines the subject's state of light stimulation, and the awakening time at which the second determination device determines the subject's state of awakening, thereby enabling the subject to be quickly synchronized when desynchronization is predicted.

[0011] FIG. 1 is a block diagram showing the configuration of a biological cycle prediction system according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of another biological cycle prediction system according to an embodiment of the present invention. FIG. 3 is a flowchart illustrating an example of the operation of another biological cycle prediction system according to an embodiment of the present invention. FIG. 4 is a characteristic diagram showing time-series data of core body temperature measured by another biological cycle prediction system according to an embodiment of the present invention and a predicted circadian rhythm. FIG. 5 is an explanatory diagram illustrating updating of parameters in a prediction formula in another biological cycle prediction system according to an embodiment of the present invention. FIG. 6 is a block diagram showing the hardware configuration of a biological cycle prediction system according to the present invention.

[0012] A biological cycle prediction system according to an embodiment of the present invention will now be described with reference to Fig. 1. This biological cycle prediction system includes a body temperature sensor 101, an illuminance sensor 102, a first determination device 103, a second determination device 104, a rhythm estimation device 105, an input device 106, and a display device 107.

[0013] The body temperature sensor 101 measures the subject's core body temperature over time as biometric information (see References 1 and 2). The body temperature sensor 101 can also measure the subject's heart rate as biometric information. The illuminance sensor 102 measures the brightness of the subject's surroundings over time. The illuminance sensor 102 can be placed, for example, near the subject's eyes.

[0014] The first determination device 103 determines whether the light stimulus state exists when the measurement value of the illuminance sensor 102 exceeds a set value. When the first determination device 103 determines whether the light stimulus state exists, it stores the time when this determination was made (light stimulus time). A set value based on, for example, the brightness at which the subject wakes up is set (stored) in the first determination device 103. The set value can be calculated in advance and set in the first determination device 103 by inputting it via the input device 106.

[0015] The second determination device 104 determines the subject's wakefulness state based on the subject's posture. When the second determination device 104 determines the wakefulness state, it stores the time of this determination. For example, the second determination device 104 measures the acceleration of the subject's movements, calculates the angle of inclination of the subject's upper body from the measured acceleration, determines the subject's posture from the calculated angle of inclination, calculates the magnitude of the subject's body movement from the measured acceleration, and determines whether the subject's posture is wakeful (awake) or asleep (lying down) based on the determined posture and the calculated magnitude of body movement (Reference 3).

[0016] The rhythm estimation device 105 uses a prediction formula created based on the phase response curve of the circadian rhythm to estimate the circadian rhythm of the subject on the day following the day on which the change in the subject's biological information was measured by the body temperature sensor 101, based on the change in the subject's biological information over the day measured by the body temperature sensor 101, the light stimulation time at which the first determination device 103 determined the light stimulation state, and the awakening time at which the second determination device 104 determined the awakening state. The rhythm estimation device 105 outputs the estimated circadian rhythm. The output circadian rhythm is displayed on the display device 107, for example.

[0017] The biological cycle prediction system may also include a timing estimation device 108, as shown in Fig. 2. The timing estimation device 108 estimates and outputs the time at which the subject will receive a light stimulus that will put the subject in an awake state on the day following the day after the circadian rhythm is estimated by the rhythm estimation device 105, based on the circadian rhythm estimated by the rhythm estimation device 105 and the subject's desired awakening time.

[0018] Furthermore, the rhythm estimation device 105 of the biological cycle prediction system according to the embodiment can update the parameters of the prediction formula based on changes in the subject's daily biological information measured by the body temperature sensor 101 on the day the rhythm estimation device 105 estimated the circadian rhythm.

[0019] The operation of the biological cycle prediction system will be described below with reference to Fig. 3. First, in a first step S101, the body temperature sensor 101 measures the subject's core body temperature in chronological order. For example, the body temperature sensor 101 measures the subject's core body temperature every 10 minutes.

[0020] In a second step S102, the illuminance sensor 102 measures the brightness of the surroundings of the subject in time series. For example, the illuminance sensor 102 measures the brightness of the surroundings of the subject every 10 minutes.

[0021] Next, in a third step S103, the first determination device 103 determines a light stimulation state in which the measurement value of the illuminance sensor 102 exceeds a set value. In addition, in a fourth step S104, the second determination device 104 determines the wakefulness state of the subject based on the posture of the subject.

[0022] Next, after measurements by the body temperature sensor 101 and the illuminance sensor 102 have been continued for 24 hours (one day), in a fifth step S105, the rhythm estimation device 105 estimates the subject's circadian rhythm for the day following the measurement of changes in the subject's biological information. Using a prediction formula created based on the phase response curve of the circannual rhythm, the rhythm estimation device 105 estimates the subject's circadian rhythm for the next day from the changes in the subject's biological information measured by the body temperature sensor 101 throughout the day, the light stimulation time at which the first determination device 103 determined the light stimulation state, and the awakening time at which the second determination device 104 determined the awakening state.

[0023] The circadian rhythm modulation of the core body temperature circadian rhythm for each timing of light stimulation is known as the light phase response curve (Non-Patent Document 2). This phase response curve is used to estimate the subject's circadian rhythm for the next day.

[0024] First, the deep body temperature of the subject measured by the body temperature sensor 101 on the current day (Nth day) is explained using the time series data as an example, where the deep body temperature changes as shown in FIG. 4(a). From this deep body temperature change, the deep body temperature nadir time mt Tmin (N), light stimulation time mtlight_expose(N), and awakening time mt wake The time of the nadir of the core body temperature is the time when the core body temperature measured by the body temperature sensor 101 is at its lowest on the day when the change in the subject's biological information is measured, and is the reference time of the circadian rhythm.

[0025] First, the obtained (measured) lowest core body temperature time mt Tminand the obtained light stimulus time mtlight_expose are used as variables: "tlight_shift = flight_shift (mt Tmin , mtlight_expose) can be used to calculate the amount of modulation of the circadian rhythm by light stimulation, tlight_shift.

[0026] Also, the lowest time of the obtained core body temperature mt Tmin and the determined (measured) awakening time mt wake and "tsleep_shift = fsleep_shift (mt Tmin , mt wake )) can be used to calculate the amount of modulation of the circadian rhythm caused by the sleep-wake rhythm, tsleep_shift.

[0027] The amount of circadian rhythm modulation due to light stimulation tlight_shift, the amount of circadian rhythm modulation due to sleep-wake rhythm tsleep_shift, and the measured core body temperature nadir time mt Tmin So, "et Tmin (N+1)=mt Tmin (N) + tlight_shift(N) + tsleep_shift(N)" to calculate the circadian rhythm of the next day (day N+1) Tmin (N+1) can be predicted [Fig. 4(b)]. Tmin (N+1) to the next day (N+1 day) Tmin (N) can be predicted.

[0028] Next, in a sixth step S106, the timing estimation device 108 compares the circadian rhythm estimated by the rhythm estimation device 105 as described above with the subject's desired awakening time it wake (N+2), first, the target deep body temperature lowest point time at Tmin (N+2) is "at Tmin (N+2) = it wake (N+2)-2hr" (estimated) [Figure 4(c)].

[0029] The lowest time of deep body temperature on day N+2 at TminUsing (N+2), the timing estimation device 108 calculates the recommended light stimulation time ptlight_expose(N+1) for day N+1 to be provided on day N using the following formula: The following formula calculates the light stimulation timing for day N+1 from the actual measurement data for day N so that the subject wakes up (wakes up) at the desired wake-up time on day N+2.

[0030] ptlight_expose(N+1)=at Tmin (N+2)-et Tmin (N+1) = it wake (N+2)-2hr-{mt Tmin (N)+tlight_shift(N)+tsleep_shift(N)}

[0031] Finally, in a seventh step S107, the rhythm estimation device 105 updates the parameters of the prediction formula based on the changes in the subject's daily biological information measured by the body temperature sensor 101 on the day the rhythm estimation device 105 estimated the circadian rhythm. Tmin The circadian rhythm on day N+1 predicted from (N) is shown by the solid line in (b) of FIG. 5, and the actual measured data mt of the circadian rhythm on day N+1 is shown by the dashed line. Tmin (N+1), the predicted data for the N+1 day, et Tmin The parameters of the function flight_shift and function fsleep_shift calculated for (N+1) are updated. As a result of the update, the circadian rhythm on the (N+2)th day can be predicted as shown in FIG.

[0032] The biological cycle prediction system can be realized by a computer. Specifically, the first determination device 103, the second determination device 104, the rhythm estimation device 105, and the timing estimation device 108 of the biological cycle prediction system according to the above-described embodiment can be implemented as computer equipment including a CPU (Central Processing Unit) 301, a main storage device 302, an external storage device 303, a network connection device 304, etc., as shown in Fig. 6, and the above-described functions can be realized by the CPU 301 operating (executing) a program loaded in the main storage device 302.

[0033] The above program causes a computer to function as the first determination device 103, the second determination device 104, the rhythm estimation device 105, and the timing estimation device 108 of the biological cycle prediction system. The above program can be recorded on a recording medium. The above program can also be provided via a network.

[0034] As described above, according to the present invention, the circadian rhythm of the subject for the day after the change in the subject's biological information measured by the body temperature sensor is estimated from the change in the subject's biological information over the day measured by the body temperature sensor, the light stimulation time at which the first determination device determined the light stimulation state, and the awakening time at which the second determination device determined the awakening state, thereby making it possible to quickly synchronize the subject when desynchronization is predicted. Conventionally, it was not possible to synchronize the biological cycle and life rhythm, measure desynchronization, or predict the state the next day, so it was not possible to quickly synchronize the subject when desynchronization was predicted. According to the present invention, it is possible to quickly synchronize the subject when desynchronization is predicted.

[0035] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0036] [References] [Reference 1] Patent No. 7026905 [Reference 2] Patent No. 7312410 [Reference 3] Patent No. 6692933

[0037] 101...body temperature sensor, 102...illuminance sensor, 103...first determination device, 104...second determination device, 105...rhythm estimation device, 106...input device, 107...display device.

Claims

1. A circadian rhythm prediction system comprising: a body temperature sensor that measures deep body temperature or heart rate as biological information of a subject in a time series; an illuminance sensor that measures the brightness around the subject in a time series; a first determination device that determines a light stimulation state in which a measurement value of the illuminance sensor exceeds a set value; a second determination device that determines the arousal state of the subject based on the posture of the subject; and a rhythm estimation device that estimates and outputs the circadian rhythm of the subject on the day following the day when the change in the biological information of the subject is measured by the body temperature sensor, from the change in the biological information of the subject in one day measured by the body temperature sensor, the light stimulation time when the first determination device determines the light stimulation state, and the arousal time when the second determination device determines the arousal state, using a prediction formula created based on the phase response curve of the circadian rhythm.

2. The circadian rhythm prediction system according to claim 1, further comprising a timing estimation device that estimates and outputs the time when the subject receives light stimulation to enter an arousal state on the day following the day when the rhythm estimation device estimates the circadian rhythm, from the circadian rhythm estimated by the rhythm estimation device and the arousal time desired by the subject.

3. The circadian rhythm prediction system according to claim 1, wherein the rhythm estimation device updates the parameters of the prediction formula based on the change in the biological information of the subject in one day measured by the body temperature sensor on the day when the rhythm estimation device estimates the circadian rhythm.

4. A program for causing a computer to function as the first determination device, the second determination device, and the rhythm estimation device included in the circadian rhythm prediction system according to any one of claims 1 to 3.

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