Sleep deprivation per se does not decrease the hypercapnic ventilatory response in humans

Several studies have found that sleep deprivation reduces the hypercapnic v entilatory response (HCVR). Such results may have been affected by uncontro lled activities or environmental influences during the sleep deprivation pe riod. The current study determined the "pure" effect of sleep deprivation o n respiratory control under strictly controlled behavioral and environmenta l conditions. After 2 d of acclimation in the laboratory, 10 subjects maint ained wakefulness (confirmed by EEC), a constant semirecumbent posture, ate regular small meals, had constant interaction with experimenters, and stay ed in an environment with constant low light (10 lux) and constant room tem perature for 41 consecutive hours. Measurements of HCVR, resting ventilatio n, (V) over dot o(2) and (V) over dot co(2) were performed every 2 h. Compa risons were made of six pairs of measurements, with each pair separated by 24 h of sleep deprivation. None of the respiratory variables changed signif icantly with 24 h of sleep deprivation. Mean HCVR increased by 17% with sle ep deprivation (3.12 versus 3.54 L min(-1) mm Hg-1; not significant). These results show that sleep deprivation per se does not reduce the sensitivity of central chemoreceptors nor change resting ventilation or metabolism. Th e reduced HCVR after sleep loss found in previous studies may have been aff ected by uncontrolled activities or environmental influences during sleep d eprivation periods.