Insomnia is coded in two different chapters, and for behavioral health the choice matters more than it looks. F51.01 (primary insomnia) sits in the mental and behavioral disorders chapter; G47.00 (insomnia, unspecified) sits in the nervous system chapter. Both are billable. But a mental health benefit is frequently carved out to a separate administrator, and which chapter a diagnosis comes from can decide which benefit is asked to pay. Below: both tables and how the choice is made.
This page is billing and administrative reference. It describes what a code means and whether it can be submitted. It is not clinical advice and does not tell anyone what to diagnose.
Used when insomnia is not due to a substance or a known physiological condition — the ICD-10-CM phrase for what older terminology called nonorganic insomnia.
| Code | Title | Billable? |
|---|---|---|
| F51.0 | Insomnia not due to a substance or known physiological condition (incomplete) | No |
| F51.01 | Primary insomnia | Yes |
| F51.02 | Adjustment insomnia | Yes |
| F51.03 | Paradoxical insomnia | Yes |
| F51.04 | Psychophysiologic insomnia | Yes |
| F51.05 | Insomnia due to other mental disorder | Yes |
| F51.09 | Other insomnia not due to a substance or known physiological condition | Yes |
| Code | Title | Billable? |
|---|---|---|
| G47.00 | Insomnia, unspecified | Yes |
| G47.01 | Insomnia due to medical condition | Yes |
| G47.09 | Other insomnia | Yes |
This is the part a code list will not tell you. Mental health benefits are frequently carved out to a separate administrator — a behavioral health organisation distinct from the medical plan, with its own network, its own authorisation rules and its own accumulators. A member can be active on the medical plan while their behavioral benefit sits somewhere else entirely.
A diagnosis from the F chapter reads as behavioral health. One from the G chapter reads as neurological. That can decide which administrator is asked to pay, whether the rendering clinician is in network for it, and whether an authorisation is required. The clinical documentation should drive the code — not the benefit — but it is worth knowing why an insomnia claim can be denied for a reason that appears to have nothing to do with insomnia.
If in doubt about where a specific plan places these, verifying the behavioral benefit before the visit is faster than appealing afterwards.
| CPT | Service | Time |
|---|---|---|
| 90791 | Psychiatric diagnostic evaluation (no medical services) | — |
| 90832 | Individual psychotherapy | 16–37 minutes |
| 90834 | Individual psychotherapy | 38–52 minutes |
| 90837 | Individual psychotherapy | 53 minutes or more |
| 90847 | Family psychotherapy, patient present | 50 minutes typical |
| 90853 | Group psychotherapy | — |
A 50-minute session is 90834, not 90837 — 90837 begins at 53 minutes.
DSM-5-TR uses insomnia disorder as its diagnosis and prints F51.01 beside it. DSM-5 collapsed the older primary-versus-secondary distinction, so the finer F51 subtypes — paradoxical, psychophysiologic — have no direct DSM-5 equivalent and come from sleep medicine terminology instead.
Afia is free and answers these by voice or chat — find a code from a condition name, confirm whether a code is billable, validate a whole list at once, or check a session length against a CPT time band. No sign-up.
It depends on the chapter. F51.01, primary insomnia, sits in the mental and behavioral disorders chapter. G47.00, insomnia unspecified, sits in the nervous system chapter. Both are billable.
F51.01 is used when insomnia is not due to a substance or a known physiological condition, and reads as a behavioral health diagnosis. G47.00 sits in the nervous system chapter and reads as neurological. Because mental health benefits are often carved out to a separate administrator, the chapter can affect which benefit is asked to pay the claim.
No. F51.0 is incomplete and needs a fifth character — F51.01 through F51.09.
DSM-5-TR lists insomnia disorder with F51.01. The finer F51 subtypes come from sleep medicine terminology and have no direct DSM-5 equivalent.
One common cause in behavioral health has nothing to do with insomnia itself: the mental health benefit may be carved out to a separate administrator, so a claim sent to the medical plan under an F-chapter code can be misrouted, or the clinician may not be in network for the carve-out. Verifying the behavioral benefit before the visit is faster than appealing afterwards.
Check a code with Afia — freeCodes on this page were verified against the CMS ICD-10-CM code sets for FY2026 and FY2027 (FY2027 effective 1 October 2026). Last reviewed 19 September 2026. Verify against the current official code set before submitting.