Effect of increasing cerebral blood flow on sleep architecture at high altitude

Background: Sleep at high altitude is dominated by lighter sleep stages, consistent with the fragmented sleep pattern caused by the many arousals from sleep associated with an almost universal occurrence of central sleep apnoea (CSA). Previous work has shown that pharmacologically increasing cerebral blood flow (CBF) reduces CSA severity; however, whether this alters sleep architecture is unknown. The aim of this study was to examine whether increases in CBF at high altitude affected sleep architecture and improved sleep quality. Methods: At 5050m, 11 subjects underwent full polysomnography monitored sleep following either iv acetazolamide (Az) (10mg/kg) combined with dobutamine (Dob) (2-5ug/kg/min) or placebo injections / i.v (order randomized). Duplex ultrasound of volumetric blood flow in the internal carotid and vertebral arteries was used to estimate global CBF prior to sleep. Results: CBF increased by 37±15% following Az/dob compared to placebo (P Conclusion: Increasing CBF reduced the severity of CSA at high altitude, resulting in less fragmented sleep and consequently less time spent in light sleep.