EFFECTS OF EVENING LIGHT ON BODY-TEMPERATURE

Six healthy male subjects aged 21-35 years participated in the present study. The subjects were exposed to dim light (150 lux) or bright lig ht (3000 lux) at eye level, from 19.00 to 21.30 h for 5 days, Rectal t emperature and wrist activity were monitored throughout the study peri od. Rectal temperature nadir was delayed significantly after che brigh t light exposure. Ease in sleep initiation and overall sleep duality, measured by questionnaire, were aggravated significantly by the evenin g bright light exposure. These results suggest that strong illuminatio n at night may disturb nocturnal sleep.