Figure 1.

Protocol schedule

The sleep restriction condition consisted of two baseline nights of 10h or 12h TIB per night (2200h–0800h/1000h) followed by five nights of sleep restricted to 4h TIB per night (0400h–0800h) and one night of 12h TIB recovery sleep (2200h-1000h). The control condition consisted of 8 consecutive nights of 10h TIB per night (2200h-0800h). Food/drink intake was ad libitum; however, prior to the measurement on SR5, sleep-restricted subjects were awake for 6h of the 10h overnight fast (2200h-0359h) and were only allowed to consume water during this time. *Body composition and metabolic measurements were collected during the morning after the first night of baseline sleep, after the fifth night of sleep restriction and after the night of recovery sleep, or after corresponding nights in the control condition. To control for morning-evening effects, measurements occurred during the two hours following waketime (between 0800h–1000h on BL1, SR5/CD5 and CD6 and between 1000h–1200h on R1). Upon awakening, subjects used the restroom. Each subject’s body composition was assessed and then subjects remained in bed in a supine position for the remainder of the testing period. After the body composition measurement, each subject’s metabolic rate was assessed. Black bars=sleep periods; white bars=wake periods; gray bar=additional 2h sleep period for subjects participating in one of the protocols.