2026 ICD-10-CM Diagnosis Code F51.11Primary hypersomnia

ICD-10-CM Codes›F01–F99›F50-F59›F51

ICD-10-CM F51.11
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

F51.11 is a billable ICD-10-CM diagnosis code for primary hypersomnia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sleep wake disorders.

Code Identity

ICD-10-CM Code
F51.11
Billable Status
Yes — Valid for Submission
Code Describes
Primary hypersomnia
Short Description
Primary hypersomnia
Same as the full description in the CMS dataset.
Parent Code
F51.1
Hypersomnia 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 CodeF51.11Primary hypersomnia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Primary hypersomnia

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.

    • Hypersomnia(organic)
      • nonorganic origin
    • Hypersomnia(organic)
      • not due to a substance or known physiological condition
    • Hypersomnia(organic)
      • primary
    • Somnolence
      • nonorganic origin

Clinical ClassificationClinical

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

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

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 F51.11 to ICD-9-CMHistory

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

ICD-9-CM
307.44 Persistent hypersomnia
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 F51.11Overview

Is F51.11 a billable code?

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

What is the ICD-9 equivalent of F51.11?

Under the General Equivalence Mappings, primary hypersomnia converts to ICD-9-CM 307.44 (persistent hypersomnia). 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.