Oversleeping (regularly needing 10–12+ hours) can be a normal variation, but if it is new or impairing, evaluate causes. First, assess sleep quality: long sleep with poor refreshment often points to fragmented sleep from sleep apnea or movement disorders. If there is severe difficulty waking, persistent daytime sleepiness, or “sleep inertia,” central hypersomnolence disorders (narcolepsy/idiopathic hypersomnia) may be considered. Depression, hypothyroidism, medications, and chronic medical illness can also contribute. Key distinction: “sleeping a lot when given the chance” (often sleep debt) versus “needing to sleep a lot regardless” (stronger medical indication). A two-week sleep diary with consistent scheduling helps clarify. Snoring, breathing pauses, morning headaches, weight gain, or leg restlessness strengthen the case for sleep-medicine evaluation. Evidence base: reviews on excessive sleepiness causes; NHLBI/AASM guidance on sleep apnea; general sleep-disorder assessment frameworks.