Figure 2.

Physiologic sleepiness (sleep latency) as a function of condition and time of day. The 11 residents in the study had sleep latencies nearly at levels associated with clinical sleep disorders (<5 minutes) in the baseline condition and below these levels in the postcall condition. No specific circadian-rhythm effect was evident in these conditions. In the sleep-extended condition, the sleep latencies were normal and showed a typical circadian rhythm effect. Error bars are standard error of the mean. Reproduced with permission from Academic Medicine (reference 2).