Breathing during sleep in normal subjects

Abstract

Sleep is associated with definite changes in respiratory function in normal humans. Whether these changes serve a specific function remains unclear and will probably not be clarified before the functions of sleep itself are better understood. Although the evidence is incomplete, respiration during sleep appears fragile, prone to instability, to upper airway obstruction, to hypoventilation, and to ventilation-perfusion mismatch, jeopardizing the homeostatic function of CO2 output and O2 uptake that it is supposed to serve. Although the other automatic homeostatic functions are executed by the autonomic nervous system (an important exception being the thermoregulatory function), ventilation, in addition to its homeostatic function, is also under voluntary control by the conscious nervous system. Voluntarily controlled ventilation gives rise to a conflict when consciousness is periodically abolished and motor control is submitted to central nervous influences specific to sleep. This conflict is incompletely solved in humans. A possible solution would be to sleep like dolphins, alternately and independently with either cerebral hemisphere.