Sleep fragmentation in obstructive sleep apnea.

Obstructive sleep apnea is associated with fragmentation of sleep due to the repeated occurrence of end-apneic arousal throughout the night. Arousals are provoked by stimuli generated during upper airway obstruction. Mechanoreceptor stimuli produced during obstructed inspiratory efforts appear to play a major role in mediating the end-apneic arousal response. The sleep disruption resulting from repeated arousals plays a major role in the pathogenesis of most of the consequences of OSA (i.e. neuropsychiatric, respiratory, and cardiovascular) and may contribute to the progression of OSA severity. However, the relative contribution of sleep fragmentation versus hypoxia in producing these complications and the precise mechanisms require further studies to be elucidated. A recently developed animal model of long-term repeated airway occlusion during sleep and a modification of the model to produce isolated sleep fragmentation should provide important new insights in this field. Treatment of the sleep disruption owing to OSA is achieved by minimizing the occurrence of arousal-promoting stimuli. This is obtained by maintaining upper airway patency during sleep.