Fig. 3.

Amylase can provide an assessment of sleep drive in real-time. (A) Bioluminescence (counts/min ± SEM) in Amy/Luc flies is high immediately after 12 h of SD (n = 9) and declines during recovery (squares). In contrast, Amy/Luc flies that have slept all night and are placed onto caffeine (2.5 mg/ml) in the morning (n = 9) show a progressive increase in bioluminescence as sleep debt accrues (circles). Flies were maintained on 0.5% sucrose supplemented with 1 mM beetle luciferin. (B) Flies null for amylase display normal sleep time and sleep consolidation (average sleep bout duration (n = 32/group). (C) amy-null flies exhibit wild-type homeostatic response after SD; data indicate cumulative sleep lost then gained after 6 h of SD. A negative slope indicates sleep lost, and a positive slope indicates sleep gained; when the slope is zero recovery is complete.