Disclosed is a sleepiness signal detector for detecting a signal, which appears before the driver of a vehicle or the operator of a machine is aware of sleepiness, over a wide range of practical conditions. The sleepiness signal detector (10) is designed such that a head movement detection means (11) detects a head movement, an eyeball movement detection means (12) detects an eyeball movement, a means (13) for calculating the ideal angular velocity of an eyeball movement calculates an ideal angular velocity of an eyeball movement based on the head movement data detected by the head movement detection means (11), a means (14) for calculating the angular velocity of an eyeball rotation calculates the angular velocity of an eyeball rotation based on the eye movement data detected by the eyeball movement detection means (12), and a means (15) for determining a sleepiness signal can detect vestibulo-ocular reflex from the ideal angular velocity of eyeball movement and the angular velocity of eyeball rotation, and determine a sleepiness signal based on the vestibulo-ocular reflex before the driver of a vehicle or the operator of a machine is aware of sleepiness.
SLEEPINESS SIGNAL DETECTOR