Abstract

ABSTRACT: Sleep loss impairs ventilatory responsiveness to hypercapnia and hypoxia, and also interferes with performance on spirometry. To test the hypothesis that the decline in hypercapnic drive due to sleep loss is mediated by endorphin production, we measured loaded and unloaded CO2 response after injection of placebo and naloxone in 11 normal subjects who were alternately rested and sleep-deprived. Blood for β-endorphin and epinephrine assay was drawn before testing each day. Unloaded CO2 response was lower after sleep loss than after sleep restoration; naloxone had no effect on this difference. Likewise, there was no difference between CO2 response after naloxone administration and CO2 response in control subjects. β-Endorphin activity did not rise after sleep loss. Loaded CO2 response was reduced compared to unloaded response and was not affected by sleep loss or by naloxone. The serum epinephrine level rose significantly with sleep loss. We conclude that naloxone is not a respiratory stimulant in normal people, and that it does not reverse the fall in CO2 response that follows sleep loss.