Arousals and the sleep apnea/hypopnea syndrome.

As daytime deficits in sleep apnea/hypopnea syndrome (SAHS) correlate poorly with earlier definitions of arousals, we investigated the relationship between microarousals and sleepiness in 63 patients with SAHS. There was a poor correlation between mean sleep latency and microarousal frequency. To determine whether arousals not detected by current definitions could account for some of the residual variance in normal subjects we used sound to induce "arousals" that were detected by rises in blood pressure but produced no visible EEG change. Such autonomic arousals produced an increase in sleepiness. We conclude that arousals not scored currently on polysomnography may contribute to the sleepiness of patients with SAHS.