ICD-10 Code G47.11 – Idiopathic hypersomnia with long sleep time (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G47.11 – Idiopathic hypersomnia with long sleep time
What it is
Idiopathic hypersomnia with long sleep time is a central sleep disorder marked by excessive daytime sleepiness and unusually prolonged sleep. The cause is not identified, and symptoms are not better explained by another sleep, medical, or substance-related condition.
Clinical signs
Typical features include chronic sleepiness, long nocturnal sleep, and difficulty waking fully. Clinical features vary; refer to documentation. Diagnostic workup often excludes narcolepsy and other causes of hypersomnolence.
When to use this code
Use this code when the record specifically documents idiopathic hypersomnia with long sleep time. Apply it for patients evaluated for persistent hypersomnolence who sleep for extended periods and whose symptoms are not attributed to another diagnosis. Check documentation if the chart only says “hypersomnia” or “sleepiness.”
Do not use for
Do not use this code for narcolepsy, sleep apnea, insufficient sleep, or hypersomnia caused by medications or another condition. If the diagnosis is unclear, check documentation rather than assuming idiopathic hypersomnia.
Coding tip
Code G47.11 only when the provider explicitly links hypersomnia to long sleep time and idiopathic origin.