2026 ICD-10-CM Diagnosis Code F51.5Nightmare disorder

ICD-10-CM Codes›F01–F99›F50-F59›F51

ICD-10-CM F51.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

F51.5 is a billable ICD-10-CM diagnosis code for nightmare disorder. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as dream anxiety disorder. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sleep wake disorders.

Code Identity

ICD-10-CM Code
F51.5
Billable Status
Yes — Valid for Submission
Code Describes
Nightmare disorder
Short Description
Nightmare disorder
Same as the full description in the CMS dataset.
Parent Code
F51
Sleep disorders not due to a substance or known physiological condition

Code Classification

ChapterF01–F99Mental and behavioural disorders
SectionF50-F59Behavioral syndromes associated with physiological disturbances and physical factors
CategoryF51Sleep disorders not due to a substance or known physiological condition
This CodeF51.5Nightmare disorder

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Dream anxiety disorder
  • Dream disorder
  • Dreaming/nightmare under general anesthesia
  • Nightmares
  • Nightmares associated with chronic post-traumatic stress disorder
  • Unpleasant dream

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Dream anxiety disorder

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disorder(of)
      • dream anxiety
    • Disorder(of)
      • nightmare
    • Disorder(of)
      • sleep
        • nightmares
    • Nightmares(REM sleep type)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS016
Sleep wake disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Nightmare Disorder

    a sleep disorder characterized by the repeated occurrence of frightening dreams which precipitate awakenings from sleep; on awakening, the individual becomes fully alert and oriented and has detailed recall of the nightmare, which usually involves imminent danger or extreme embarrassment to the individual.

Patient EducationClinical

Sleep Disorders

Sleep is a complex biological process. While you are sleeping, you are unconscious, but your brain and body functions are still active. They are doing a number of important jobs that help you stay healthy and function at your best. So when you don't get enough quality sleep, it does more than just make you feel tired.

The full article covers:

  • What is sleep?
  • What are sleep disorders?
  • What causes sleep disorders?
  • What are the symptoms of sleep disorders?
  • How are sleep disorders diagnosed?
  • What are the treatments for sleep disorders?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert F51.5 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
307.47 Sleep stage dysfunc NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About F51.5Overview

Is F51.5 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report nightmare disorder on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of F51.5?

Under the General Equivalence Mappings, nightmare disorder converts to ICD-9-CM 307.47 (sleep stage dysfunc NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.