Fig. 2: Morphine increases wake during the dark cycle.

A Minutes awake per hour at baseline. B Minutes in NREM per hour at baseline. C Minutes REM per hour at baseline. D Minutes awake per hour at acute morphine timepoint. E Minutes NREM per hour at acute morphine timepoint. F Minutes REM per hour at acute morphine timepoint. G Minutes awake per hour at chronic morphine timepoint. H Minutes NREM per hour at chronic morphine timepoint. I Minutes REM per hour at chronic morphine timepoint.