2027 ICD-10-CM Diagnosis Code G47.12Idiopathic hypersomnia without long sleep time

ICD-10-CM Codes›G00–G99›G40-G47›G47

ICD-10-CM G47.12
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G47.12 is a billable ICD-10-CM diagnosis code for idiopathic hypersomnia without long sleep time. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 887. Coders also document this condition as idiopathic hypersomnia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sleep wake disorders.

Code Identity

ICD-10-CM Code
G47.12
Billable Status
Yes — Valid for Submission
Code Describes
Idiopathic hypersomnia without long sleep time
Short Description
Idiopathic hypersomnia without long sleep time
Same as the full description in the CMS dataset.
Parent Code
G47.1
Hypersomnia

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG47Sleep disorders
This CodeG47.12Idiopathic hypersomnia without long sleep time

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Idiopathic hypersomnia
  • Idiopathic hypersomnia without long sleep time

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G47.12: its own notes plus those printed at G47.1, G47, and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

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 G47.1 Hypersomnia applies to 6 codes
From G47 Sleep disorders applies to 43 codes
From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G47.12, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming G47.12: its condition is not part of those codes, and both may be reported when the patient has both.

  • F51.1 Hypersomnia not due to a substance or known physiological condition
    idiopathic hypersomnia (G47.11, G47.12)
  • F51 Sleep disorders not due to a substance or known physiological condition
    organic sleep disorders (G47.-) names G47.-, 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

  • Hypersomnia

    a sleep disorder characterized by excessive sleepiness.

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 G47.12 to ICD-9-CMHistory

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

ICD-9-CM
327.12 Idio hypersom-no lng slp
Exact Match The mapping is direct, with no qualifiers.

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 G47.12Overview

What is the ICD-10 code for idiopathic hypersomnia without long sleep time?

The ICD-10-CM code for idiopathic hypersomnia without long sleep time is G47.12 (sometimes written as G4712). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G47.12 (Hypersomnia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report idiopathic hypersomnia without long sleep time on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G47.12 group to?

When idiopathic hypersomnia without long sleep time 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 G47.12?

Under the General Equivalence Mappings, idiopathic hypersomnia without long sleep time converts to ICD-9-CM 327.12 (idio hypersom-no lng slp). The mapping is a direct match.