F51.3 ICD-10-CM Code: Sleepwalking [somnambulism]
HCC Buddy Code Card
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FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Behavioral syndromes associated with physiological disturbances and physical factors (F50-F59)
F51.3
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSleepwalking [somnambulism]
A sleep disorder where a person walks, talks, or performs complex activities while asleep without being aware of it.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Non-rapid eye movement sleep arousal disorders, sleepwalking type
Excludes 2
Official- organic sleep disorders (G47.-)
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for F51.3 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for F51.3 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for F51.3 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for F51.3 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for F51.3 in this effective period.
Buddy Documentation Tip
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is F51.3 an HCC code?
No. F51.3 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- F51.3
- Description
- Sleepwalking [somnambulism]
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
F51.3 is the ICD-10-CM diagnosis code for sleepwalking [somnambulism]. A sleep disorder where a person walks, talks, or performs complex activities while asleep without being aware of it. F51.3 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering behavioral syndromes associated with physiological disturbances and physical factors (f50-f59).
F51.3 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Document whether episodes occur during NREM or REM sleep if specified.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for F51.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document whether episodes occur during NREM or REM sleep if specified
- •Note frequency and any injuries or safety concerns during episodes