SLEEP EVALUATION DEVICE AND SLEEP EVALUATION METHOD THEREFOR

• US 20090171165A1
• Filed: 12/09/2008
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Tanita Corporation (Tanita)
• Original Assignee: Tanita Corporation (Tanita)
• Inventors: Izumi, Shuichi
• Granted Patent: US 8,622,921 B2
• Time in Patent Office: Days
• US Class Current: 600/300
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices

Abstract

A sleep evaluation device (1) has a sensor unit (2) that constantly detects body movements of a human subject on bedding, and has a determiner that, based on results of detection, determines a sleep state and an aroused state of the human subject. The determiner quantifies results of detection of the sensor unit into N number of body movement data (where, N is a positive integral number satisfying N≧2) and obtains, based on G number of standard deviations for each of G groups (in which G is an integral number satisfying 2≦G<N) dividing N number of body movement data and for each body movement data and gs (gs<G) number of standard deviations selected therefrom, L number of average value of standard deviations (where L is an integral number satisfying 2≦L≦G). The determination of a sleep state and an aroused state of the human subject is based on G number of standard deviations and L number of average values of standard deviations.

Claims

1. A sleep evaluation device comprising:

a body movement detector that constantly detects body movements of a human subject lying on bedding; and

a determiner that determines, based on results of the detection of the body movement detector, at least whether the human subject is in a sleep state or is in an aroused state,

wherein the determiner quantifies, at a predetermined time interval, the results of the detection of the body movement detector as N number of body movement data, in which N is a positive integral number satisfying N≧

2,

wherein the determiner obtains G number of standard deviations for each of G groups dividing the N number of body movement data and for each body movement data included in each group, in which the G is an integral number satisfying 2≦

G<

N,

wherein the determiner obtains L number of average values of standard deviations on the basis of gs number of standard deviations (gs<

G) that have been selected from the G number of standard deviations, in which L is an integral number satisfying 2≦

L≦

G, and

wherein the determiner determines, on the basis of the G number of standard deviations and the L number of average values of standard deviations, whether the human subject is in a sleep state or is in an aroused state.

2. A sleep evaluation device according to claim 1,

wherein the determiner obtains the L number of average values on the basis of consecutive gs number of standard deviations (gs<

G), from among the G number of standard deviations,

wherein the determiner obtains, as a baseline value, from among the L number of average values of standard deviations, the average value of all the pth average values of standard deviations that satisfy a condition that an absolute value of a difference between the pth average value of standard deviations and (p+1)th average value of standard deviations is equal to or is less than a predetermined value, in which p is an integral number satisfying p≦

L−

1, and

wherein the determiner determines, based on the baseline value, whether the human subject is in a sleep state or is in an aroused state.

3. A sleep evaluation device according to claim 2,

wherein the determiner obtains the L number of average values of standard deviations as a moving average value of the gs number of standard deviations.

4. A sleep evaluation device according to claim 1,

wherein the determiner determines, in a case in which any one of the G number of standard deviations falls below a predetermined value E, that the human subject was in an aroused state at a point in time at which a result of detection was obtained, on the basis of which result of the detection body movement data was obtained and on the basis of which body movement data the standard deviation that has fallen below the predetermined value E was calculated.

5. A sleep evaluation device according to claim 1,

wherein the determiner determines, in a case in which, from among the G number of standard deviations, a (q+1)th standard deviation is greater than a value obtained by adding a predetermined value F1 to a qth standard deviation, that the human subject was in an aroused state at a point in time at which a result of detection was obtained, on the basis of which result of detection body movement data was obtained and on the basis of which body movement data the (q+1)th standard deviation was calculated, in which q is an integral number satisfying q≦

G−

1.

6. A sleep evaluation device according to claim 1,

wherein the determiner determines, in a case in which any one of the G number of standard deviations is greater than a predetermined value F2, that the human subject was in an aroused state at a point in time at which a result of detection was obtained, on the basis of which result of detection the body movement data was obtained and on the basis of which body movement data the standard deviation was calculated.

7. A sleep evaluation device according to claim 2,

wherein the determiner obtains a standard deviation of the G number of standard deviations as an overall standard deviation,

wherein the determiner obtains an index showing the quantity of body movements of the human subject by subtracting the baseline value from the average value of G number of standard deviations and by dividing a resulting value of the subtraction by the overall standard deviation, and

wherein the determiner determines a point in time at which a transition from an sleep state to an aroused state has taken place on the basis of the index showing the quantity of body movements of the human subject.

8. A sleep evaluation device according to claim 1,

wherein the body movement detector includes a mattress containing a predetermined fluid and detects body movements of the human subject depending on changes in pressure of the fluid.

9. A sleep evaluation method comprising:

obtaining N number of body movement data by quantifying, at a predetermined time interval, body movements of a human subject lying on bedding, in which N is a positive integral number;

obtaining G number of standard deviations for each of G groups dividing the N number of body movement data and for each body movement data included in each group, in which the G is an integral number satisfying 2≦

G<

N;

obtaining L number of average values of standard deviations on the basis of gs standard deviations (gs<

G) that have been selected from the G number of standard deviations, in which L is an integral number satisfying 2≦

L≦

; and

determining, on the basis of the G number of standard deviations and the L number of average values of standard deviations, whether the human subject is in a sleep state or is in an aroused state.