noun
hypersomnia
Medical term for excessive sleepiness or prolonged nighttime sleep. Used in clinical contexts.
過眠症の患者は日中に強い眠気を感じることが多い。
Patients with hypersomnia often feel strong sleepiness during the day.
General term for sleep disorders; 過眠症 is a specific type.
Compound of 過 (excessive) + 眠 (sleep) + 症 (condition/syndrome). A straightforward medical term.