Figure 4.

(A) Sleep behavior for a group of wild-type (WT) female flies in a 12:12 hr light:dark cycle. Flies have short bouts of siesta sleep in the middle of the day (more pronounced in males) and a relatively consolidated period of sleep at night. (B) Sleep behavior for WT and per⁰¹ male flies in constant darkness (DD). per⁰¹ flies, which do not display circadian rhythms of activity, spend approximately the same amount of time in sleep, but have sleep that is fragmented across the day. Data appear slightly noisier as fewer flies are represented compared to (A).