Monitoring a sleeping subject
Apparatus and methods are described, including apparatus for use with a subject who shares a bed with a second person. A motion sensor detects motion of the subject and motion of the second person, and generates a motion signal in response thereto. A control unit identifies components of the motion signal that were generated in response to motion of the subject, by distinguishing between components of the motion signal that were generated in response to motion of the subject, and components of the motion signal that were generated in response to motion of the second person. The control unit analyzes the components of the motion signal that were generated in response to motion of the subject and generates an output in response thereto. Other applications are also described.
1. Apparatus for use with a subject who is a first person, who shares a bed with a second person, the apparatus comprising:
a thin, flat motion sensor configured to be placed underneath a portion of the bed, and, while disposed underneath the portion of the bed, to:
detect motion of the subject without contacting the subject, without contacting clothes the subject is wearing, without viewing the subject, and without viewing clothes the subject is wearing,
detect motion of the second person without contacting the second person, without contacting clothes the second person is wearing, without viewing the second person, and without viewing clothes the second person is wearing, and
generate a motion signal in response to detecting motion of the subject and motion of the second person; and
a control unit configured to:
identify components of the motion signal that were generated in response to motion of the subject, by distinguishing between components of the motion signal that were generated in response to motion of the subject, and components of the motion signal that were generated in response to motion of the second person,
analyze the components of the motion signal that were generated in response to motion of the subject, and
generate an output in response thereto,
wherein the motion sensor comprises a mechanical-filtering element configured to reduce a response of the motion sensor to motion of the second person, relative to motion of the subject.
2. The apparatus according to claim 1 , wherein the control unit is configured to identify components of the motion signal that were generated in response to motion of the subject, by identifying components of the motion signal that have a signal strength that is a characteristic signal strength of a motion signal of the subject.
3. The apparatus according to claim 1 , wherein the control unit is configured to identify components of the motion signal that were generated in response to motion of the subject by identifying components of the motion signal that have a pattern that is a characteristic pattern of motion of the subject.
4. The apparatus according to claim 1 , further comprising a weight sensor that is configured to detect when the subject is lying above the motion sensor, wherein the control unit is configured to identify the components of the motion signal that were generated in response to motion of the subject, in response to a signal that is generated by the weight sensor.
5. The apparatus according to claim 1 , wherein the motion sensor is configured to facilitate the identification of components of the motion signal that were generated in response to motion of the subject, by strengthening a signal strength of the components of the motion signal that are generated in response to motion of the subject.
6. The apparatus according to claim 5 , wherein the apparatus is for use with a subject who lies on a mattress, and wherein the sensor is configured to be placed at a position selected from the group consisting of: underneath the mattress at a position that is higher than a head of the subject is typically placed, and adjacent to and in contact with a side of the mattress.
7. The apparatus according to claim 6 , wherein the sensor is configured such as to facilitate identification, by the control unit, of components of the motion signal that were generated in response to a longitudinal cardio-ballistic effect of the subject.
8. The apparatus according to claim 1 , wherein the control unit is configured to identify components of the motion signal that were generated in response to respiratory motion of the subject.
9. The apparatus according to claim 1 , wherein the control unit is configured to identify components of the motion signal that were generated in response to cardiac motion of the subject.
10. The apparatus according to claim 1 , wherein the control unit is configured to identify components of the motion signal that were generated in response to large body-movement of the subject.
11. The apparatus according to claim 1 , wherein the control unit is further configured to:
analyze the motion signal,
in response thereto, identify an effect of large body-movement of the second person on sleep of the subject, and
in response thereto, generate a sleep-disturbance output.
12. The apparatus according to claim 11 , wherein the sleep-disturbance output includes an assessment of an effectiveness of a parameter at reducing the effect of the large body-movement of the second person on the sleep of the subject, the control unit being configured to generate the assessment of the effectiveness of the parameter.
13. The apparatus according to claim 12 , wherein the parameter is selected from the group consisting of: a parameter of a mattress on which the subject is sleeping, a parameter of the bed, a sleeping arrangement of the subject and the second person, and a room-environment parameter, the control unit being configured to generate the assessment of the effectiveness of the selected parameter.
14. The apparatus according to claim 11 , wherein the sleep-disturbance output includes a recommendation to reduce the effect of the large body-movement of the second person on the sleep of the subject by adjusting an adjustable parameter, the control unit being configured to generate the recommendation.
15. The apparatus according to claim 14 , wherein the adjustable parameter is selected from the group consisting of: a parameter of a mattress on which the subject is sleeping, a parameter of the bed, a sleeping arrangement of the subject and the second person, and a room-environment parameter, the control unit being configured to generate the recommendation to adjust the selected parameter.
16. The apparatus according to claim 11 , wherein the sleep-disturbance output includes instructions to a device to adjust an adjustable parameter, the control unit being configured to generate the instructions.
17. The apparatus according to claim 16 , wherein the adjustable parameter is selected from the group consisting of: a parameter of a mattress on which the subject is sleeping, a parameter of the bed, a sleeping arrangement of the subject and the second person, and a room-environment parameter, the control unit being configured to generate the instructions to the device to adjust the selected parameter.
18. The apparatus according to claim 1 , wherein the motion sensor consists of a single motion sensor.
19. The apparatus according to claim 1 , wherein the control unit is further configured to:
by analyzing the motion signal, assess an effectiveness of the mechanical-filtering element at reducing the response of the motion sensor to motion of the second person, and
generate an output in response thereto.
20. The apparatus according to claim 1 , wherein the mechanical filtering element comprises an edge region of the motion sensor that is more rigid than a central portion of the motion sensor.
21. The apparatus according to claim 1 , wherein the control unit is configured to (a) analyze a portion of the motion signal that was generated in response to motion of the subject, (b) calculate an amplitude threshold based on the analysis, and (c) identify that a given portion of the motion signal was generated in response to motion of the second person, and not in response to motion of the subject, by identifying that the amplitude of the given portion of the motion signal is less than the amplitude threshold.
22. The apparatus according to claim 21 , wherein the control unit is configured to calculate the amplitude threshold as a multiple of the amplitude of the components of the motion signal that were generated in response to motion of the subject.
23. The apparatus according to claim 1 , wherein the control unit is configured to identify that a portion of the motion signal was generated in response to motion of the second person, and not in response to motion of the subject, by (i) comparing (a) an amplitude of a component of the motion signal generated in response to motion of the subject following the portion to (b) an amplitude of a component of the motion signal generated in response to motion of the subject before the portion, and (ii) determining that the portion of the motion signal was generated in response to motion of the second person, and not in response to motion of the subject, if the amplitude of the component of the motion signal following the portion has changed by less than a threshold amount relative to the amplitude of the component of the motion signal before the portion.
24. The apparatus according to claim 1 , wherein the control unit is configured to identify that a portion of the motion signal was generated in response to motion of the second person, and not in response to motion of the subject, by identifying that the portion exhibits ringing.
25. The apparatus according to claim 24 , wherein the control unit is configured to identify that the portion of the motion signal generated in response to motion of the second person exhibits ringing by ascertaining that the portion includes a set of at least three consecutive extrema each of which is separated from the preceding extremum of the set by a time that falls within a given time range.
26. The apparatus according to claim 25 , wherein the time range is 0.15-0.45 seconds.
27. The apparatus according to claim 24 , wherein the control unit is configured to identify that the portion of the motion signal generated in response to motion of the second person exhibits ringing by:
ascertaining that the portion includes a set of at least three consecutive extrema each of which is separated from the preceding extremum of the set by a time that falls within a given time range, and
further ascertaining that respective differences between (i) magnitudes of the set of consecutive extrema, and (ii) a magnitude of an extremum that precedes the set of consecutive extrema, fall within a given amplitude range.
28. The apparatus according to claim 27 , wherein the given amplitude range is 10%-150% of the magnitude of the extremum that precedes the set of consecutive extrema.