Excessive daytime sleepiness in a general population sample: the role of sleep apnea, age, obesity, diabetes, and depression.

CONTEXT: Excessive daytime sleepiness (EDS) is commonly considered a cardinal sign of sleep apnea; however, the mechanism underlying the association is unclear.
OBJECTIVE: The purpose of this study was to assess the association between the complaint of EDS and sleep apnea, considering a wide range of possible risk factors in a population sample. DESIGN AND
SETTING: We examined this question in the Penn State cohort (a random sample of 16,583 men and women from central Pennsylvania, ranging in age from 20 to 100 yr). A random subset of this cohort (n = 1,741) was further evaluated for one night in the sleep laboratory. MAIN OUTCOME MEASURE: The main measure was a complaint of EDS.
RESULTS: The final logistic regression model indicated depression was the most significant risk factor for EDS followed by body mass index, age, typical sleep duration, diabetes, smoking, and finally sleep apnea. The strength of the association with EDS decreased with increasing age, whereas the association of depression with EDS was stronger in the young. EDS is more prevalent in the young (<30 yr), suggesting the presence of unmet sleep needs and depression, and in the very old (>75 yr), suggesting increasing medical illness and health problems. EDS was associated with a reduced report of typical sleep duration without any association with objective polysomnographic measures.
CONCLUSIONS: It appears that the presence of EDS is more strongly associated with depression and metabolic factors than with sleep-disordered breathing or sleep disruption per se. Our findings suggest that patients with a complaint of EDS should be thoroughly assessed for depression and obesity/diabetes independent of whether sleep-disordered breathing is present.