Self-reported levels of sleepiness among subjects with insomnia

Objectives: To determine the prevalence of sleepiness in a cohort of insomnia subjects. We evaluated if differential levels of subjective sleepiness predict systematic differences in the polysomnographic characteristics of these subjects. Background: Insomnia is prevalent among the adult population. While it has been speculated that sleepiness may be an important daytime consequence of insomnia, this has not been demonstrated. Methods: Sixty-two subjects with complaints of insomnia for at least 6 months were polysomnographically evaluated. Subjects were asked to self-report their level of sleepiness based on their experiences for the previous 7 days. Subjects were divided into three groups based on their level of sleepiness. Sleepiness was determined using the excessive daytime sleepiness scale of the Sleep/Wake Activity Inventory (SWAI-EDS). Results: Twenty-two percent of insomnia subjects were found to be sleepy on the EDS scale of the SWAI. The level of sleepiness was also found to predict difficulty initiating sleep both on the nocturnal scale of the SWAI, and on nocturnal polysomnography. Conclusions: This study established a base rate of sleepiness among a cohort of insomnia subjects. It also demonstrated a wide spectrum of sleepiness/alertness among subjects with insomnia. Differential levels of sleepiness were found to predict nocturnal sleep latencies. (C) 2001 Elsevier Science B. V. All rights reserved.