ICD-10 Code G47.12 – Idiopathic hypersomnia without long sleep time (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G47.12 – Idiopathic hypersomnia without long sleep time
What it is
G47.12 identifies idiopathic hypersomnia without long sleep time, a central disorder of hypersomnolence. Use it when documentation shows excessive daytime sleepiness that is not better explained by another sleep, medical, or psychiatric condition.
Clinical signs
Typical findings include persistent daytime sleepiness, prolonged or unrefreshing naps, and difficulty waking. Clinical features vary; refer to documentation and supporting sleep-study or specialist evaluation when available.
When to use this code
Use this code when the provider documents idiopathic hypersomnia and specifically notes the patient does not have long sleep time. It may also apply when the assessment distinguishes this disorder from narcolepsy or other causes of hypersomnolence. Check documentation if the subtype is unclear.
Do not use for
Do not use G47.12 for narcolepsy, insomnia, or sleepiness clearly caused by another condition or medication. If the record does not support idiopathic hypersomnia without long sleep time, check documentation.
Coding tip
Capture the exact subtype stated by the clinician, because “with long sleep time” and “without long sleep time” are coded differently.