Figure 1

Experimental protocol. Breakfast was served between 07:30 h and 08:00 h, lunch between 12:10 h and 12:40 h, and supper between 19:10 h and 19:40 h. For days 2 to 5, subjects rose at 07:00 h and answered the OSAsleep inventory after their urine sample had been collected (indicated by a white arrow underneath the time scale). Subjects in groups Poor*Dim and Rich*Dim continuously stayed under dim light (<50 lx) whereas subjects in groups Poor*Bright and Rich*Bright stayed under bright light (>5,000 lx) between 7:30 h and 18:00 h. Saliva was collected every hour between 18:00 h and 00:00 h (black arrows) and subjects retired at 00:00 h after emptying their bladder.