Fig. 3.

Sleep/wake cycles of typical transgenic and wild-type mice. Hypnograms represent concatenated 20-sec epochs of EEG/EMG activity, scored as awake (W), non-REM sleep (N), or REM sleep (R). Seven hours per mouse, including transitions from light phase to dark phase (solid bar), are shown. The orexin/ataxin-3-transgenic mouse exhibits fragmentation of wakefulness during the dark phase and frequent premature onsets of REM sleep that occur immediately after wakefulness (arrowheads) or after <1 min of preceding non-REM sleep (arrows). In contrast, the orexin/ataxin-3;CAG/orexin-double-transgenic mouse has more consolidated wakefulness during the dark phase. As in the wild-type mouse, no direct or premature transitions from wakefulness to REM sleep were ever observed in the double-transgenic mouse.