Sleep and breathing

Significant physiologic changes in breathing take place during normal sleep related to alterations in respiratory drive and musculature. Significant physiologic changes in breathing take place during normal sleep related to alterations in respiratory drive and musculature. Set point of ventilation is different in wakefulness and sleep. pCO2 is higher and ventilation is lower in sleep. Sleep onset in normal subjects is not immediate, but oscillates between arousal, stage I and II sleep before steady NREM sleep is obtained. So falling asleep results in decreased ventilation and a higher pCO2, above the wakefulness set point. On wakefulness, this constitutes an error signal which provokes hyperventilation until the wakefulness set point is reached. When the subject falls asleep, ventilation decreases and pCO2 rises, resulting in hypoventilation or even apnea. These oscillations continue until steady state sleep is obtained. The medulla oblongata controls our respiration.