Frequent breathing-related electroencephalogram arousals in four patients with mild obstructive sleep apneas.

We report cases of four patients with mild obstructive sleep apnea syndrome (OSAS) with frequent breathing-related electroencephalogram (EEG) arousals which led to excessive daytime sleepiness. In spite of a relatively low apnea hypopnea index (AHI), sleep was disrupted by frequent EEG arousals associated with respiratory effort as observed in upper airway resistance syndrome. The effects of sleep stage and sleep position on EEG arousals were also investigated. We consider that AHI alone is not a sufficient index to assess severity of OSAS, and it is very important to examine microarousals by the alteration of esophageal pressure in addition to the effect of sleep position.