Figure 1: Differences (incremental values) in the normalized leptin concentrations (mean ± SEM) relative to the 5-hour sleep/dim-light condition. Sample concentrations collected at 60, 90, and 120 minutes for the 8-hour sleep/dim-light condition, those for the 5-hour sleep/red-light condition, those for the 5-hour sleep/green-light condition, and those for the 5-hour sleep/blue-light condition were each normalized to the values obtained at 60, 90, and 120 minutes for the reference, 5-hour sleep/dim-light condition. These normalized values were averaged across subjects and times. The incremental values reflect the difference in the averages of the four different sleep/lighting conditions from the 5-hour sleep/dim-light condition. Incremental values after the 8-hour sleep/dim-light condition and after all three lighting conditions were significantly () greater than those in the reference, 5-hour sleep/dim-light condition.