Mood disorders are highly prevalent in patients investigated with a multiple sleep latency test.

PURPOSE: Excessive daytime sleepiness (EDS) is a debilitating symptom which occurs commonly in both primary sleep and mood disorders. The prevalence of mood disorders in patients with EDS, evaluated objectively with a mean sleep latency test (MSLT), has not been reported. We hypothesize that mood disorders are highly prevalent in patients being investigated for EDS. This study aims to report the prevalence of mood disorder in the MSLT population and investigate the association between mood disorder and objective and subjective scores of sleepiness.

METHODS: A retrospective multicenter study of adults with a MSLT and Hospital Anxiety and Depression Score (HADS) identified over a 3-year period. The HADS is a validated questionnaire in detecting depression (HADS-D ≥ 8) and anxiety (HADS-A ≥ 11) in the sleep clinic population. Data collected included demographics, medical, and sleep study information. Mood disorder prevalence was compared to the general sleep clinic population. Correlation between measures of sleepiness and mood was performed.

RESULTS: Two hundred twenty patients were included with mean age 41.1 ± 15.7 years, mean body mass index 28.6 kg/m2 of whom 30% had anxiety (HADS-A > 11) and 43% depression (HADS-D > 8). Mean results for the cohort are ESS 13.7, mean sleep latency 11.5 min, HADS-A 8.2, and HADS-D 7. There was no significant correlation between objective sleepiness, as measured by the mean sleep latency, and either HADS-A (-0.006, p = 0.93) or HADS-D score (0.002, p = 0.98). There was, however, a weak correlation between subjective sleepiness, as measured by the ESS, and the mean sleep latency (-0.25, p < 0.01), HADS-A (0.15, p = 0.03), and HADS-D (0.2, p = 0.004). There was no significant association between diagnosis of hypersomnia disorders and presence of anxiety (p = 0.71) or depression (p = 0.83).

CONCLUSIONS: Mood disorders are highly prevalent in the MSLT population. There was a weak correlation found between subjective measures of sleepiness and mood disorders, but not between objective measures of sleepiness and mood disorders. Routine screening for mood disorders in patients with hypersomnolence should be considered.