The frequency of multiple sleep onset REM periods among subjects with no excessive daytime sleepiness

The multiple sleep latency test (MSLT) is a valuable tool in the assessment of excessive daytime sleepiness (EDS). Additionally, multiple sleep onset rapid eye movement periods (SOREMPs) are a frequent occurrence in patients with narcolepsy. To date, however, few studies have evaluated the frequency of SOREMPs in a population of healthy control subjects. Subjects participating in a variety of sleep studies were screened with a nocturnal clinical polysomnogram, followed by the MSLT. Subjects were required to be drug free and have no sleep-related symptoms or medical or psychiatric conditions. Of the 139 subjects who were screened, 24 (17%) had two or more SOREMPs. These individuals were more likely to be male, younger, and sleepier than those with one or zero SOREMPs. The etiology of two or more SOREMPs in healthy controls was not apparent from the clinical or polysomnographic evaluation. Although it is possible that these findings are early signs of narcolepsy, subjects reported being free of any sleep-related complaints. Further investigations into the determinants of multiple SOREMPs and their reliability among asymptomatic populations are warranted.