APPARATUS AND METHODS FOR MONITORING A SUBJECT

Apparatus and methods are described for use with a seat () of a vehicle, including a sensor unit () configured to be placed underneath the seat and configured to detect motion of a subject who is sitting on the seat during motion of the vehicle. The sensor unit includes a housing (), a first motion sensor () disposed within the housing such as to generate a first sensor signal that is indicative of the motion of the vehicle, and a second motion sensor () disposed within the housing, such as to generate a second sensor signal that is indicative of the motion of the subject and the motion of the vehicle. A computer processor at least partially distinguishes between motion of the subject and motion of the vehicle by analyzing the first and second sensor signals. Other applications are also described.