JP4224935B2 - Sleep state determination method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sleep state determination method for determining a sleep state of a living body based on a pulse wave measured from the living body.
[0002]
[Prior art]
Conventionally, a human sleep state (sleeping depth) can be determined by polysomnography which simultaneously measures biological signals such as electroencephalogram, eye movement, myoelectricity, and electrocardiogram. However, measurement by polysomnography requires a large amount of equipment and requires hospitalization. In addition, since it is necessary to wear sensors on the head and face, there is a problem that the wearing feeling is bad, sleep is hindered by attaching the sensors, and accurate inspection cannot be performed.
In view of this, as a means for replacing sleep polygraphy, a method has been proposed in which the sleep state is determined based on changes in the respiratory rate and pulse rate during sleep (see JP-A-3-41926).
[0003]
[Problems to be solved by the invention]
However, in the method of detecting the sleep state from the respiratory rate and pulse rate during sleep, the pulse interval corresponding to the RR interval of the electrocardiogram is obtained, and the sleep state (REM sleep and non-REM sleep) is determined from the fluctuation (fluctuation) of the pulse interval. Judgment. In this case, in order to obtain the pulse interval, it is necessary to accurately detect the peak (top or bottom) of the pulse wave for each beat. However, when the pulse wave is stable, the peak of the pulse wave can be detected relatively accurately.However, if the pulse wave is disturbed due to body movements during sleep, the peak of the pulse wave is caused by factors other than blood flow. Since the deviation occurs, the peak of the pulse wave may be erroneously detected.
For this reason, in order to obtain | require an exact pulse interval, complicated calculation processing was required and it was difficult to determine a sleep state simply.
[0004]
In addition, fluctuations in the pulse interval associated with REM sleep and non-REM sleep occur in healthy humans, but fluctuations in the pulse interval are reduced in humans and elderly people who are detrimental to health, so REM sleep and non-REM sleep Is difficult to determine.
The present invention has been made based on the above circumstances, and its purpose is easier to calculate than the determination method based on fluctuations in pulse interval, and is less susceptible to noise associated with body movement, etc. It is in providing the sleep state determination method which can determine a sleep state (REM sleep and non-REM sleep) correctly.
[0006]
[Means for Solving the Problems]
(Means of Claim 1 )
In the sleep state determination method of the present invention, the height of each beat of the pulse wave measured from a living body is obtained as the wave height. It is characterized in that it is determined as REM sleep. In this determination method, even if the extraction of the peak or bottom of the pulse wave becomes somewhat inaccurate, the fluctuation state of the wave height does not change greatly, so the sleep state is determined from the fluctuation of the conventional pulse interval. In comparison, the calculation process is overwhelmingly simple, and the sleep state can be easily determined.
[0009]
(Means of Claim 2 )
In the sleep state determination method according to claim 1 ,
An index indicating the fluctuation state of the wave height is obtained by statistical processing.
[0011]
(Means of claim 3 )
In the sleep state determination method according to claim 2 ,
At least one of an average value, a maximum value, a minimum value, a variance value, and a deviation of each data measured in a certain time is obtained as the index.
[0012]
(Means of claim 4 )
The sleep state determination method according to any one of claims 1 to 3 ,
Creating a pulse wave or al height measured in human wrist or forearm.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows pulse wave measurement data.
The sleep state determination method of the present embodiment creates one or more of an envelope, wave height, and baseline of a pulse wave measured from a living body (human), and changes the envelope, wave height, and baseline. Is determined as non-REM sleep, and when the fluctuation of the envelope, wave height, and baseline is fluctuating, it is determined as REM sleep. As shown in FIG. 1, the envelope is a line connecting the vertices or bottom points of each beat of the pulse wave, the wave height is the height of each individual pulse wave, and the baseline is Says a line connecting the centers of wave heights.
This sleep state determination is performed by a sleep state determination device 1 (see FIG. 2) incorporating a CPU (microprocessor).
[0014]
Below, the process sequence of the sleep state determination apparatus 1 which determines a sleep state is demonstrated based on the flowchart shown in FIG.
Step 10 ... The pulse wave is measured from the pulse wave information (electric signal) detected by the pulse wave sensor 2 during sleep (see FIG. 1). For example, as shown in FIG. 2, the pulse wave sensor 2 may be a known optical type having a light emitting element 2a and a light receiving element 2b, or an ultrasonic type, a Doppler type, a pressure type, or the like. The pulse wave sensor 2 is worn on a human wrist or finger or the like, converts the detected pulse wave into an electrical signal (for example, a voltage signal), and outputs the electrical signal to the sleep state determination device 1.
[0015]
Step20… The pulse wave data measured in Step10 is passed through a digital filter to cut unnecessary frequency components.
Step30 ... A peak for each beat is detected from the pulse wave data.
Step40 ... Create one or more of envelope, wave height, baseline. Here, a case where an envelope is created will be described. As described above, the envelope is created by connecting the peaks of the measured pulse waves for each beat. One of the envelope A created by connecting the vertices of the pulse wave and the envelope B created by connecting the bottoms of the pulse wave may be used.
[0016]
Step 50: Detect the fluctuation state of the envelope. Here, at least one obtained by statistical processing such as an average value, a maximum value, a minimum value, a variance value, and a deviation of an envelope over a fixed time (for example, 20 seconds) is used as an index, and a change in the value is detected.
Step 60: The sleep state is determined from the fluctuation state of the envelope. Here, when the variation of the index obtained by the statistical processing of Step 50 is within a certain range (for example, variation within 25%), it is determined as non-REM sleep, and when it is more than that, it is determined as REM sleep.
Step70 ... Displays the sleep state determined in Step60.
[0017]
(Operation and effect of this embodiment)
When comparing the fluctuation state of the pulse wave envelope, wave height, and baseline measured during sleep with the fluctuation state of the pulse interval, the fluctuation state of the envelope, wave height, and baseline is substantially constant as shown in FIG. At times, the fluctuation state of the pulse interval is also substantially constant. However, as shown in FIG. 5, when the fluctuation state of the envelope, the wave height, and the baseline is fluctuating, it can be seen that the fluctuation state of the pulse interval is also fluctuating.
It is already known that when the fluctuation state of the pulse interval is substantially constant, it is non-REM sleep, and when the fluctuation state of the pulse interval is fluctuating, it is REM sleep.
Therefore, as shown in FIG. 4 and FIG. 5, since there is a correlation between the fluctuation state of the envelope, wave height, and baseline and the fluctuation state of the pulse interval, the sleep state (REM) depends on the fluctuation state of the envelope, wave height, and baseline. Sleep and non-REM sleep).
[0018]
Actually, when the envelope data is compared between REM sleep and non-REM sleep, as shown in FIG. 6, it can be seen that the variation state of the envelope is larger during REM sleep than during non-REM sleep. When the standard deviation for each 20 seconds is obtained from the envelope data, during non-REM sleep, 0.15 at 0 to 20 seconds, 0.16 at 20 to 40 seconds, and 0.16 at 40 to 60 seconds are almost changed. Absent. However, during REM sleep, 0.16 at 0-20 seconds, 0.09 at 20-40 seconds, 0.10 at 40-60 seconds, and 0.15 at 60-80 seconds. Yes. That is, the standard deviation has changed significantly (fluctuated). Therefore, when the fluctuation state of the envelope is substantially constant (when the fluctuation of the index obtained by statistical processing is within a range), it is determined as non-REM sleep, and when the fluctuation state of the envelope is fluctuating (obtained by statistical processing) If the fluctuation of the index exceeds a certain range), it can be determined as REM sleep.
[0019]
According to the determination method of the present embodiment, even if the extraction of the peak or bottom of the measured pulse wave becomes somewhat inaccurate, the fluctuation state of the envelope does not change greatly, so that the conventional pulse Computation processing is overwhelmingly simple compared with the method of determining a sleep state from the fluctuation | variation of an interval, and can determine a sleep state easily.
In addition, since this determination method does not require an accurate pulse interval, measurement accuracy on the time axis is not so required, so that it is resistant to disturbances and an extremely good S / N ratio can be obtained.
Furthermore, since the envelope, wave height, and baseline represent the respiratory state, the determination method of this embodiment can also be applied to the diagnosis of sleep apnea and the like.
[0020]
FIG. 3 is a flowchart for determining the sleep state based on the fluctuation state of the envelope. However, as shown in FIGS. 7 and 8, the sleep state can be determined by the same processing procedure even in the case of the wave height and the baseline. it can.
[Brief description of the drawings]
FIG. 1 shows pulse wave measurement data.
FIG. 2 is a cross-sectional view showing a mounted state of a pulse wave sensor.
FIG. 3 is a flowchart showing a processing procedure of a sleep state determination apparatus.
FIG. 4 is a graph showing a fluctuation state of an envelope, a wave height, a baseline, and a fluctuation state of a pulse interval (when the fluctuation state is substantially constant).
FIG. 5 is a graph showing a fluctuation state of an envelope, a wave height, a baseline, and a fluctuation state of a pulse interval (when the fluctuation state fluctuates).
FIG. 6 is a graph showing envelope data during REM sleep and non-REM sleep.
FIG. 7 is a flowchart showing a processing procedure of the sleep state determination apparatus.
FIG. 8 is a flowchart showing a processing procedure of the sleep state determination apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sleep state determination apparatus 2 Pulse wave sensor A Envelope B Envelope

Claims (4)

  The height of each pulse wave measured from a living body is obtained as the wave height, and when the fluctuation state of the wave height is substantially constant, it is determined as non-REM sleep, and when the fluctuation state of the wave height is fluctuating, it is determined as REM sleep. Sleep state determination method. In the sleep state determination method according to claim 1 ,
The sleep state determination method characterized by calculating | requiring the parameter | index which shows the fluctuation state of the said wave height by statistical processing. In the sleep state determination method according to claim 2 ,
A sleep state determination method, wherein at least one of an average value, a maximum value, a minimum value, a variance value, and a deviation of each data measured in a certain time is obtained as the index. The sleep state determination method according to any one of claims 1 to 3 ,
Sleeping state determination method characterized by creating a pulse wave or al the wave height measured by the human wrist or forearm.

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