During exposure, the subjects were allowed to eat light food and drink (non-caffeinated beverages only). Participants were requested to go to the bathroom before testing and were not allowed leave the room for the duration of the testing. Following the light exposure, participants were connected to the sleep testing system by a skilled technician and requested to go to sleep. Bedtimes and wake times were based on the average sleep/wake time as indicated in the individual actigraphy reports. Oral temperature was taken at six time points, three on the testing night: 21:00h, 23:00h, and immediately prior to bedtime and at three the following morning, at 0, 60, and 120 minutes after awakening. Urine samples were collected at three time points: 21:00h, 23:00h, and immediately following morning awakening. This protocol was repeated for each of the four testing nights. Upon completion of the study protocol participants were given monetary compensation for their participation in the study.