ICD-11

Hypersomnia due to a medication or substance is characterised by excessive nocturnal sleep, daytime sleepiness, or excessive napping that is attributable to the sedating effects of medications, alcohol, or other psychoactive substances, including withdrawal syndromes (e.g., from stimulants) and is sufficiently severe to constitute an independent focus of clinical attention.

Note: A definitive diagnosis requires use of polysomnography and multiple sleep latency test (MSLT) to rule out other hypersomnolence disorders or other sleep disorders (e.g. obstructive sleep apnea) which might better explain the sleepiness.