Denton EJ, et al. - This study determined the prevalence of mood disorder in the mean sleep latency test (MSLT) population, as well explored the link between mood disorder and objective and subjective scores of sleepiness, presuming a high prevalence of mood disorders in this population. Findings reported a high prevalence of mood disorders in the MSLT population and a weak correlation between subjective measures of sleepiness and mood disorders, but not between objective measures of sleepiness and mood disorders. A recommendation was made for consideration of routine screening for mood disorders in patients with hypersomnolence.