Disclosed is a system for monitoring incapacity of a machine operator or a vehicle operator. The system comprises a means to measure one or more eye and eyelid movements including saccades and blinks in at least one eye of the operator. There is a storage means to continuously record the measurements. The system further comprises a data processor means to analyse the eye or eyelid movement to obtain a measure of period of ocular quiescence. When the measurement reaches a predetermined value an alarm means is triggered.
