Monitoring a subject

1. A computer-implemented method of monitoring a subject, the method comprising:

following detection of a first fall of the subject and a revocation of a fall alert for the first fall due to detecting the subject has stood up after the first fall, obtaining first measurements of movement of the subject, by a device that is to be worn by a subject and that comprises a sensor for generating first measurements of movement of the subject;

determining, by the device, a first value of at least one mobility characteristic of the subject from the obtained first movement measurements;

determining, by the device, if the mobility of the subject has degraded after the first fall based on the first value of the at least one mobility characteristic and a second value of the at least one mobility characteristic, wherein the second value is determined from second movement measurements obtained prior to the first fall; and

in response to determining that the mobility of the subject has degraded after the first fall, by the device, performing a fall alert action in respect of the first fall.

2. A method as claimed in claim 1 , wherein the step of performing a fall alert action comprises:

issuing an alert to request assistance for the subject.

3. A method as claimed in claim 2 , wherein an alert comprises at least one of an audible alarm, placing a call to a call center, emergency service, or nominated recipient, or sending data to a call center, emergency service, or nominated recipient.

4. A method as claimed in claim 1 , wherein the step of performing a fall alert action, comprises:

issuing a prompt to the subject to trigger an alert that the subject has fallen and/or that the subject requires assistance.

5. A method as claimed in claim 1 , wherein the step of determining if the mobility of the subject has degraded after the first fall comprises:

determining the difference between the first value of the at least one mobility characteristic and the second value of the at least one mobility characteristic; and

determining that the mobility of the subject has degraded if the difference between the first value of the at least one mobility characteristic and the second value of the at least one mobility characteristic is more than a threshold amount.

6. A method as claimed in claim 1 , wherein the second value for the at least one mobility characteristic represents a normal value for the at least one mobility characteristic.

7. A method as claimed in claim 1 , wherein prior to the step of obtaining first measurements of movements of the subject, the method further comprises:

issuing a prompt to the subject requesting the subject perform a mobility action; and

wherein the step of obtaining first measurements of the movements is performed while the subject is performing the mobility action.

8. A non-transitory computer readable storage medium storing computer readable code, the code being configured such that, on execution by a suitable computer or processor in a device that is to be worn by a subject and that comprises a sensor for generating first measurements of movement of the subject, the computer or processor is caused to perform the method as claimed in claim 1 .

9. An apparatus for monitoring a subject, comprising:

a processing unit, in a device that is to be worn by a subject and that comprises a sensor for generating first measurements of movement of the subject, that is configured to:

following detection of a first fall of the subject and a revocation of a fall alert for the first fall due to detecting the subject has stood up after the first fall, obtain first measurements of movement of the subject, by the device;

determine a first value of at least one mobility characteristic of the subject from the obtained first movement measurements, by a device;

determine if the mobility of the subject has degraded after the first fall based on the first value of the at least one mobility characteristic and a second value of the at least one mobility characteristic, by the device, wherein the second value is determined from second movement measurements obtained prior to the first fall; and

in response to determining, by the device, that the mobility of the subject has degraded after the first fall, perform a fall alert action in respect of the first fall.

10. An apparatus as claimed in claim 9 , wherein the processing unit is configured to perform a fall alert action by:

issuing an alert to request assistance for the subject.

11. An apparatus as claimed in claim 9 , wherein the processing unit is configured to perform a fall alert action by:

issuing a prompt to the subject to trigger an alert that the subject has fallen and/or that the subject requires assistance.

12. An apparatus as claimed in claim 9 , wherein the processing unit is configured to determine if the mobility of the subject has degraded after the first fall by:

determining the difference between the first value of the at least one mobility characteristic and the second value of the at least one mobility characteristic; and

determining that the mobility of the subject has degraded if the difference between the first value of the at least one mobility characteristic and the second value of the at least one mobility characteristic is more than a threshold amount.

13. An apparatus as claimed in claim 9 , wherein the second value for the at least one mobility characteristic represents a normal value for the at least one mobility characteristic.

14. An apparatus as claimed in claim 9 , wherein the processing unit is further configured to, prior to obtaining the first measurements of movements of the subject, issue a prompt to the subject requesting the subject perform a mobility action; and, the processing unit is configured to obtain the first measurements of the movements while the subject is performing the mobility action.

15. A system for monitoring a subject, the system comprising:

a device that is to be worn by a subject and that comprises a sensor for generating first measurements of movement of the subject; and an apparatus as claimed in claim 9 .

16. A wearable device to be worn by a subject and that comprises a sensor for generating first measurements of movement of the subject for monitoring a subject, comprising:

a processing unit, in the device, that is configured to:

following detection of a first fall of the subject and a revocation of a fall alert for the first fall due to detecting the subject has stood up after the first fall, by the device, obtain first measurements of movement of the subject;

determine, by the device, a first value of at least one mobility characteristic of the subject from the obtained first movement measurements;

determine, by the device, if the mobility of the subject has degraded after the first fall based on the first value of the at least one mobility characteristic and a second value of the at least one mobility characteristic, wherein the second value is determined from second movement measurements obtained prior to the first fall; and

in response to determining that the mobility of the subject has degraded after the first fall, perform, by the device, a fall alert action in respect of the first fall a sensor configured to generate the second movement measurements of the subject prior to the first fall, and further configured to generate the first measurements of movement of the subject after the first fall;

interface circuitry configured to communicate the fall alert action; and

a power supply configured to power the sensor and the interface circuitry.

17. The apparatus of claim 16 , wherein the sensor comprises an accelerometer, an air pressure sensor, a magnetometer, a gyroscope, a satellite positioning system receiver, a pressure sensor, a skin conductivity sensor, and/or a photoplethysmography sensor.

18. The apparatus of claim 16 , further comprising a memory unit configured to store the second movement measurements of the subject prior to the first fall and/or the determined second value of the at least one mobility characteristic.