OBESITY WITHOUT SLEEP-APNEA IS ASSOCIATED WITH DAYTIME SLEEPINESS

Background: Daytime sleepiness and fatigue is a frequent complaint of obese patients even among those who do not demonstrate sleep apnea. Ob jective: To assess in the sleep laboratory whether obese patients with out sleep apnea are sleepier during the day compared with healthy cont rols with normal weight. Methods: Our sample consisted of 73 obese pat ients without sleep apnea, upper airway resistance syndrome, or hypove ntilation syndrome who were consecutively referred for treatment of th eir obesity and 45 controls matched for age. All patients and healthy controls were monitored in the sleep laboratory for 8 hours at night a nd at 2 daytime naps, each for 1 hour the following day. Results: Obes e patients compared with controls were sleepier during the day and the ir nighttime sleep was disturbed, During both naps, sleep latency, wak e time after onset of sleep, and total wake time were significantly lo wer, whereas the percentage of sleep time was significantly higher in obese patients compared with controls. In contrast, during the nightti me testing, obese patients compared with controls demonstrated signifi cantly higher wake time after onset of sleep, total wake time, and low er percentage of sleep time. An analysis of the relation between night time and daytime sleep suggested that daytime sleepiness in obese pati ents is a result of a circadian abnormality rather than just being sec ondary to nighttime sleep disturbance. Conclusions: Daytime sleepiness is a morbid characteristic of obese patients with a potentially signi ficant impact on their lives and public safety. Daytime sleepiness in individuals with obesity appears to be related to a metabolic and/or c ircadian abnormality of the disorder.