(A) Expression of 5HT7-GAL4. (B) Activation of 5HT7-GAL4+ neurons increases the number of daytime sleep episodes without changing total sleep compared to control, inducing rebound sleep after activation ends. Data are presented as the change (in min) from baseline day. (C) The probability of state transition from sleep to wake, P(wake), significantly decreased during rebound sleep, while probability of transition from wake to sleep, P(doze), increased during activation. Data are expressed as change from baseline day. (D) Expression of VT038828-GAL4 (VT-GAL4). (E) Activation of VT-GAL4+ neurons significantly increased the number of daytime episodes, with no effect on total sleep compared to controls. (F) P(doze) is increased compared to controls upon activation but there were no changes in P(wake). See also Figures S5–6, Videos S1-2.