2026 ICD-10-CM Diagnosis Code F51

Code attributes

• Non-billable/Non-specific code

Coding rules

• Specify the leaf code — the parent code (e.g. F32) is a navigational header; billing requires a leaf code (F32.0, F32.1, etc.) that matches the documented presentation.
• Document onset, course, and severity (mild / moderate / severe) plus functional impact. Payers use this combination when adjudicating medical necessity.
• Attach a validated instrument score (PHQ-9, GAD-7, PCL-5, or equivalent) at intake and at follow-up where applicable. Objective measures support code selection and continued authorization.
• Review at every visit and update if presentation changes — including remission and partial remission states.

Clinical information

F51 codes non-organic sleep disorders — distinct from G47 sleep disorders, which cover those due to medical causes. Includes the insomnia subtypes (F51.01–F51.09), hypersomnia (F51.11–F51.19), parasomnias (F51.3 sleepwalking, F51.4 night terrors, F51.5 nightmare disorder), and unspecified codes. Document sleep onset/maintenance pattern, daytime impairment, and rule out substance-induced and primary medical causes (which would route to G47).