Momentary rise in breathing rate during light sleep in mice and humans

Abstract

Breathing activity during sleep is closely related to sleep stage. Indeed, breathing rate (BR) during rapid eye movement (REM) sleep show much larger fluctuation than that during deep sleep. In the present study, breathing movement of freely moving C57B6/J mice were analyzed during sleep by piezoelectric device placed on the floor of the cage in a non-invasive manner (PCT/2003/001109), while animal behavior was monitored by an infrared camera. We found that mice momentarily exhibited an extraordinary large rise in BR by up to 14 breaths/sec during sleep. Such rise in BR was detected in all four mice tested, especially after atonia and shortly before awakening (mean BR = 10.5±1.2 breaths/sec, which is 4.3±1.3 times the BR in stable deep sleep; mean duration = 0.4±0.1 sec). In humans, interestingly, a similar momentary increase in BR by up to 116 breaths/min (2.4-3.7 times the BR in deep sleep) was detected during REM sleep in normal volunteers tested. No such increase was detected in stages 3 and 4. In addition, more prolonged increase in BR also was observed during REM/light sleep in human subjects. Further studies may clarify the correlation between the central regulation mechanisms of respiration and sleep stages. [J Physiol Sci. 2006;56 Suppl:S137]