ICD-10 Code F51.5 – Nightmare disorder (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F51.5 – Nightmare disorder
What it is
F51.5 identifies nightmare disorder, a sleep disorder marked by repeated, well-remembered frightening dreams. The person usually wakes fully alert and can describe the dream content.
Clinical signs
Typical features include recurrent nightmares, abrupt awakening from sleep, and clear recall of disturbing dream imagery. Clinical features vary; refer to documentation.
When to use this code
Use F51.5 when the record documents nightmare disorder or recurrent nightmares causing sleep disruption. Code it when the provider identifies the condition as the diagnosis, not just an isolated bad dream. If nightmares are linked to another documented disorder, check documentation for the primary diagnosis.
Do not use for
Do not use this code for ordinary, occasional bad dreams without a diagnosed disorder. Do not assign it when nightmares are better explained by another condition and the provider does not document nightmare disorder.
Coding tip
Look for explicit provider wording such as “nightmare disorder” or “recurrent nightmares” before assigning F51.5.