Reviewed by Jonathan Teplitsky · Updated August 2026
What a sleep apnea nexus letter must contain to be effective
To move the needle on a VA claim, a sleep apnea nexus letter needs five things: the provider's credentials, a statement that they reviewed your records or claims file, a clear diagnosis backed by a sleep study, a medical rationale explaining why the link exists, and the conclusion that your sleep apnea is "at least as likely as not" related to your service or a service-connected condition. Miss any of these and the letter loses weight. The rest of this page gives you a real, fill-in-the-blank template you can hand to your provider.
What a nexus letter is, and why sleep apnea is usually a secondary claim
A nexus letter is a doctor's written medical opinion that connects a diagnosed condition to its cause. For VA purposes that cause is either direct (something that happened in service) or secondary (another already service-connected condition). Sleep apnea is most often filed as a secondary claim. It commonly develops because of PTSD or another mental health condition, or because weight gain from a service-connected orthopedic condition limits exercise. Medication for a service-connected condition can also relax the airway and worsen apnea. If you want the foundations first, see what is a nexus letter, our general nexus letter template, and the PTSD nexus letter template for the sleep-apnea-secondary-to-PTSD pairing.
The 5 elements of a strong nexus letter
- Credentials. Who the provider is, their license/specialty, and why they are qualified to give the opinion.
- Records reviewed. A statement that they reviewed your service records, medical history, and/or C-file, not just a single visit.
- Diagnosis. The specific condition, e.g., obstructive sleep apnea confirmed by a polysomnogram (sleep study), rated under Diagnostic Code 6847.
- Rationale. The medical "because": the reasoning and any literature explaining why the sleep apnea is connected to its cause. This is the heart of the letter.
- Conclusion. The "at least as likely as not" opinion stating the link.
The "at least as likely as not" standard
VA does not require certainty. Service connection only needs a probability of 50% or greater, phrased as "at least as likely as not." Because of the benefit-of-the-doubt rule in 38 CFR 3.102, when the evidence is in equipoise (a 50/50 tie) VA must decide in the veteran's favor. That is why this exact wording matters: vaguer phrases like "could be related" or "possibly connected" fall below the threshold and give a rater room to deny.
Weight tip: The conclusion sentence alone is not enough. A bare "it is at least as likely as not" with no reasoning is given little probative value. The rationale, the explanation of the medical mechanism plus a reference to the sleep study confirming the diagnosis, is what makes the opinion persuasive to a rater or the Board.
Fill-in-the-blank nexus letter template
Copy the version that fits your claim, replace every [bracketed] placeholder, and have your provider review, complete, and sign it on their letterhead.
Secondary sleep apnea (most common)
[Provider Name], [Credentials/License] · [Clinic / Address] · [Date]
RE: [Veteran Name], [VA File Number / SSN]
I am a [physician / sleep medicine specialist / psychiatrist / NP] licensed in [State], with [X] years treating [sleep disorders / the relevant field]. I have reviewed [Veteran]'s service treatment records, VA medical records, polysomnogram results, and claims file (C-file).
[Veteran] is diagnosed with [obstructive sleep apnea] confirmed by a sleep study dated [date]. [Veteran] is service-connected for [primary condition, e.g., PTSD or a lumbar spine condition] at [XX]%.
It is my professional medical opinion that [Veteran]'s [obstructive sleep apnea] is at least as likely as not (50% or greater probability) caused by, or alternatively aggravated beyond its natural progression by, the service-connected [primary condition].
Rationale: [Explain the mechanism, e.g., PTSD-related sleep fragmentation and hyperarousal are medically associated with worsened sleep-disordered breathing, or weight gain from reduced activity due to the service-connected orthopedic condition is a documented risk factor for OSA. Cite the chronology in the records, the sleep study findings, and any supporting medical literature.]
Sincerely, [Signature] · [Provider Name, Credentials]
Direct service connection
[Same header and credentials block as above.]
It is my professional medical opinion that [Veteran]'s [obstructive sleep apnea] is at least as likely as not (50% or greater probability) related to [his/her] active military service.
Rationale: [Tie the sleep apnea to an in-service event or documented symptom, e.g., records show complaints of snoring, witnessed apnea episodes, or daytime fatigue during service, symptoms have been continuous since separation, and the clinical picture including the current sleep study is consistent with onset during that period.]
Sincerely, [Signature] · [Provider Name, Credentials]
Who can write it
The opinion must come from a qualified medical provider, typically a physician, sleep medicine specialist, pulmonologist, or in many cases a nurse practitioner or physician assistant. A psychiatrist or psychologist treating an underlying mental health condition can also write the secondary opinion if they address the sleep-apnea connection specifically. It can be your treating provider or an independent provider you hire. A statement the veteran writes about their own symptoms is valuable as a lay statement, but it is not a medical nexus and cannot replace the provider's signed opinion, and it cannot substitute for a sleep study diagnosis.
How sleep apnea is rated (DC 6847)
Sleep apnea is rated under 38 CFR 4.97, Diagnostic Code 6847 (Sleep Apnea Syndromes, obstructive, central, and mixed):
| Rating | Criteria |
|---|---|
| 0% | A documented sleep disorder that is asymptomatic, or a condition not requiring treatment. |
| 30% | Persistent daytime hypersomnolence (chronic daytime sleepiness that does not improve with sufficient sleep). |
| 50% | Requires use of a breathing assistance device, such as a CPAP machine. |
| 100% | Chronic respiratory failure with carbon dioxide retention, cor pulmonale, or requires a tracheostomy. |
These are the current criteria as of this writing. VA has a long-pending proposal that would tie the 50% rating to how well treatment controls symptoms rather than to CPAP use alone, but no final rule has taken effect, so the CPAP-based table above still applies to claims filed today.
Common mistakes that sink nexus letters
- Using weak language ("could be," "possibly") instead of "at least as likely as not."
- Stating the conclusion with no rationale. The reasoning is what gives the opinion weight.
- No statement that the records, C-file, or sleep study were reviewed.
- Forgetting the secondary aggravation path: a service-connected condition can worsen existing sleep apnea even if it did not cause it.
- Filing without a polysomnogram on record. VA needs an objective sleep study to confirm the diagnosis.
- An unsigned letter, or one signed by the veteran rather than a provider.
Important: This is an educational template, not legal or medical advice. The nexus letter must be completed, reviewed, and signed by a qualified medical provider. For DBQ-related questions, see our DBQ explained guide, and for help with a denial or appeal, see whether you need a VA appeals attorney.
Sleep apnea nexus letter: quick FAQ
Can I write my own nexus letter? You can draft the template, but a qualified provider must author and sign the actual opinion.
What's the magic phrase? "At least as likely as not," meaning a 50% or greater probability, which triggers benefit-of-the-doubt under 38 CFR 3.102.
Is sleep apnea primary or secondary? Most often secondary, commonly linked to PTSD, another mental health condition, or weight gain from a service-connected orthopedic condition.
Do I need a sleep study? Yes. A polysomnogram confirming the diagnosis is required before VA will grant service connection or a rating under DC 6847.
Does the rationale matter more than the conclusion? Yes. A conclusion without reasoning is given little weight.
What code is sleep apnea rated under? DC 6847 under 38 CFR 4.97, at 0/30/50/100%, with 50% tied to CPAP use.