In the present invention, the breathing of a subject is detected, breathing rates within a breathing rate calculation period are output on the basis of the detected breathing, and a breathing rate variation coefficient is calculated using the average and standard deviation of breathing rates within predetermined periods. By comparing the breathing rate variation coefficient with the average breathing rate variation coefficient which is the average of breathing rate variation coefficients from sleep to wake-up, it is possible to determine whether the sleep state of the subject is rapid eye movement sleep or non-rapid eye movement sleep. This allows for the provision of sleep state determination device or the like which are able to readily and accurately evaluate sleep by using, for example, the breathing rate or heart rate as biological information of the subject within a predetermined period.
SLEEP STATE DETERMINATION DEVICE, SLEEP STATE DETERMINATION METHOD, AND PROGRAM