Fig. 2.
Conditional wake probability is a measure of sleep depth. (A–E) Results of a mechanical arousal threshold experiment. (A) Schematic of experimental setup. Fly locomotion in a 96-well plate was monitored using a FlyBox. At 3-h intervals starting at ZT 1, an electromagnetic solenoid was used to tap the side of the plate. (B) Circadian profiles of % Time Asleep, P(Doze), and P(Wake). Solid lines are the population means; tinded bands are the 95% confidence intervals. Behavior was measured at 25 °C (green) and 29 °C (magenta). Tapping times are indicated by dashed vertical lines. Gray area indicates lights-off period. (C) Response to tapping was measured as the increase in arousal probability following a tap. The percentage (%) responding is plotted at 25 °C (green) and 29 °C (magenta). The symbol “#” indicates a response greater than chance (P < 0.05) as measured by Fisher’s exact test with the Holm’s step-down correction for multiple testing. (D) The effect of temperature on P(Wake) (cyan), P(Doze) (yellow), and response to tapping (pink) at each time (ZT). (E) The P(Wake) and P(Doze) of each time point was normalized by converting it to a z-score. The behavior of each fly following each tap was classified as a nonresponse (no activity 1 min after tap) or as a response. The mean z-score across all time points for responders and nonresponders is plotted. Error bars are SEM. *P < 0.05; ***P < 0.0005.