2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

F51.11 is a billable ICD-10-CM diagnosis code for primary hypersomnia. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 887. 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to F51.11: its own notes plus those printed at F51.1, F51, and Chapter 5. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 5 (F01-F99) Mental and behavioural disorders applies to 872 codes
  • disorders of psychological development

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From F51.1 Hypersomnia not due to a substance or known physiological condition applies to 4 codes
From F51 Sleep disorders not due to a substance or known physiological condition applies to 15 codes
  • organic sleep disorders (G47.-)
From Chapter 5 (F01-F99) Mental and behavioural disorders applies to 872 codes
  • symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name F51.11, its category, or a range that includes it.

Excludes2 4

These codes carry an Excludes2 note naming F51.11: its condition is not part of those codes, and both may be reported when the patient has both.

  • G47.1 Hypersomnia
    primary hypersomnia (F51.11)
  • F98 Other behavioral and emotional disorders with onset usually occurring in childhood and adolescence
    sleep disorders not due to a substance or known physiological condition (F51.-) names F51.-, which includes this code
  • G47 Sleep disorders
    nonorganic sleep disorders (F51.-) names F51.-, which includes this code
  • G47.1 Hypersomnia
    hypersomnia not due to a substance or known physiological condition (F51.1-) names F51.1-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

  • Idiopathic Hypersomnia

    a disorder of central nervous system etiology characterized by excessive sleepiness during the daytime.

Patient EducationClinical

Sleep Disorders

While you are sleeping your brain and body functions are still active. Sleep is a natural process that helps your body restore energy, supports learning and memory, and keeps you healthy.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About F51.11Overview

What is the ICD-10 code for primary hypersomnia?

The ICD-10-CM code for primary hypersomnia is F51.11 (sometimes written as F5111). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

What MS-DRG does F51.11 group to?

When primary hypersomnia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 887 (other Mental Disorder Diagnoses), which carries a relative weight of 1.1154. Higher weights mean higher Medicare reimbursement.

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.