Study objective: To determine the sleep/wake habits of patients diagnosed as having obstructive sleep apnea (ie, respiratory event index [REI] ≥5).
Design: Case series with prospective data collection to determine the relationship among sleepiness, REI, and sleep/wake habits. Patients were grouped according to their multiple sleep latency test (MSLT) results (≤5 and >5) and REI (mild REI ≤20; moderate REI >20 but ≤60; and severe REI >60).
Setting: An American Sleep Disorders Association-accredited sleep laboratory.
Patients: Three hundred ninety (325 male, 65 female) consecutive patients seen between June 1993 and January 1995 for evaluation of sleep apnea. This included a sleep, medical, and psychiatric evaluation followed by a physical examination. Sleep histories and sleep/wake habits were recorded by a physician trained in sleep medicine. Polysomnographic evaluation consisted of a nocturnal clinical polysomnogram (CPSG) and an MSLT on the following day. Of 390 patients, 268 completed polysomnographic evaluation (CPSG and MSLT).
Measurements and results: Sleepy (MSLT ≤5) patients with mild (REI ≤20) and moderate apnea (REI >20 ≤60) reported spending significantly less time in bed than sleepy patients with severe apnea (REI >60). Those with severe apnea (REI >60) reported napping significantly more and experienced a more severe disruption of their routine daily activities because of sleepiness when compared with mild and moderate OSA patients.
Conclusions: These data suggest that sleep habits have an important modulatory effect on the level of sleepiness and this effect is lost as the severity of sleep-disordered breathing increases.