Figure 2.

Circadian and sleep state-dependent effects on ventilation. (A) 72-h traces of average minute ventilation (top), tidal volume (middle) and breathing frequency (bottom) in adult male rats housed under a 12:12 h light:dark cycle and receiving room air (21% O₂, balance N₂). Solid horizontal bars at the bottom indicate periods where lights were off. (B) 24-h trace of average minute ventilation in rats during wake, non-rapid eye movement (NREM) sleep, and rapid-eye movement (REM) sleep as indicated. All animals housed in a 12:12 h light:dark cycle. (A) Redrawn with permission from Seifert and Mortola (2002). (B) Redrawn with permission from Stephenson et al. (2001).