Physiological and Genomic Consequences of Intermittent Hypoxia: Selected Contribution: Regulation of sleep-wake states in response to intermittent hypoxic stimuli applied only in sleep

Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8 Recurrent sleep-related hypoxia occurs in common disorders such as obstructive sleep apnea (OSA). The marked changes in sleep after treatment suggest that stimuli associated with OSA (e.g., intermittent hypoxia) may significantly modulate sleep regulation. However, no studies have investigated the independent effects of intermittent sleep-related hypoxia on sleep regulation and recovery sleep after removal of intermittent hypoxia. Ten rats were implanted with telemetry units to record the electroencephalogram (EEG), neck electromyogram, and body temperature. After >7 days recovery, a computer algorithm detected sleep-wake states and triggered hypoxic stimuli (10% O 2 ) or room air stimuli only during sleep for a 3-h period. Sleep-wake states were also recorded for a 3-h recovery period after the stimuli. Each rat received an average of 69.0 ± 6.9 hypoxic stimuli during sleep. The non-rapid eye movement (non-REM) and rapid-eye-movement (REM) sleep episodes averaged 50.1 ± 3.2 and 58.9 ± 6.6 s, respectively, with the hypoxic stimuli, with 32.3 ± 3.2 and 58.6 ± 4.8 s of these periods being spent in hypoxia. Compared with results for room air controls, hypoxic stimuli led to increased wakefulness ( P