Sleep Apnea ICD-10 Codes: What G47.33, G47.31, and G47.37 Mean — and What Medicare Requires for CPAP

If you came here for one code, here it is: obstructive sleep apnea is G47.33. Central sleep apnea is usually G47.31 (primary) or G47.37 (when it is caused by another condition). And when the type of apnea is not known yet, the honest code is G47.30, sleep apnea, unspecified. Those three codes cover nearly every sleep apnea diagnosis in the United States — but the code on your record decides whether a sleep study or a CPAP machine gets paid for, so the details matter.

Sleep apnea is common. The National Heart, Lung, and Blood Institute (NHLBI)  notes that 50 to 70 million Americans have a sleep disorder, and researchers estimate that nearly 1 billion adults worldwide live with obstructive sleep apnea. Untreated, it raises the risk of stroke, heart attack, and high blood pressure. This guide explains the full G47.3 code family in plain language, how the diagnosis is confirmed, and what Medicare requires before it pays for CPAP. Every code below was checked against the CMS ICD-10-CM tabular list for fiscal year 2027 (effective October 1, 2026 through September 30, 2027).

The short answer: the three codes that matter most

Most people only ever need one of these four codes. If you remember nothing else, remember this table.

How we verified these codes

ICD-10 codes change every year, and a wrong code can mean a denied claim, so nothing in this article comes from memory. We checked every code against the CMS ICD-10-CM tabular list for fiscal year 2027, cross-checked the descriptors on the AAPC code reference, and verified the coverage rules against Medicare’s own documents: Local Coverage Determination L33718 for positive airway pressure devices and its companion Policy Articles A52467 and A57697. Symptoms and diagnosis information comes from the National Heart, Lung, and Blood Institute (NHLBI). Where a code’s meaning depends on a Medicare rule rather than the code book, we say so.

The complete sleep apnea code family (G47.3)

All sleep apnea codes live under category G47.3, inside the G47 sleep disorders category, in Chapter G00–G99 (diseases of the nervous system) of ICD-10-CM. There are nine billable codes under G47.3. Note that G47.3 itself is a category, not a billable code — it should never appear alone on a claim.

The same G47 category also holds the codes for the rest of sleep medicine — insomnia (G47.00–G47.09), hypersomnia (G47.10–G47.19), narcolepsy (G47.411 with cataplexy, G47.419 without), circadian rhythm disorders, and parasomnias. Our guide to narcolepsy vs sleep apnea explains how the narcolepsy codes differ from the apnea codes.

G47.33: obstructive sleep apnea (adult) (pediatric)

G47.33 is the workhorse code of sleep medicine. It describes obstructive sleep apnea — the airway repeatedly narrows or closes during sleep, cutting off airflow even though the chest keeps trying to breathe. It is a billable code, valid on HIPAA-covered claims for fiscal year 2027, and it has been unchanged since ICD-10-CM began in 2015. Its ICD-9 equivalent was 327.23.

The single most misunderstood fact about G47.33 is that there is no separate code for mild, moderate, or severe obstructive sleep apnea. There is no G47.331 for mild and no G47.333 for severe. Severity is measured by the apnea-hypopnea index (AHI) from the sleep study — the number of breathing pauses or shallow breaths per hour of sleep — and it is documented in the chart, not in the code:

That AHI number is what Medicare’s coverage policy actually checks — the code just names the disease. A patient with an AHI of 8 and a patient with an AHI of 45 both carry G47.33; what differs is the documentation that supports treatment.

Two exclusion notes govern G47.33. The code itself carries an Excludes1 note for obstructive sleep apnea of newborn (P28.3) — the two can never be reported together. And the parent category G47.3 excludes apnea not otherwise specified (R06.81), Cheyne-Stokes breathing (R06.3), pickwickian syndrome (E66.2), and sleep apnea of newborn (P28.3). The tabular list also says to code any associated underlying condition alongside the apnea code.

G47.31 and G47.37: central sleep apnea

Central sleep apnea is a different disease from obstructive apnea, even though the symptoms overlap. In central apnea, the airway is open — the problem is that the brain does not send reliable signals to the breathing muscles. There is no blockage to hold open, which is why the coding, the testing, and the treatment all differ.

G47.31, primary central sleep apnea, is used when central apnea is the diagnosis and no underlying condition explains it. Risk factors the NHLBI lists for central apnea include heart failure, stroke, some nerve and muscle conditions, long-term opioid pain medicines, and premature birth — but if one of those is documented as the cause, the code changes.

G47.37, central sleep apnea in conditions classified elsewhere, is used when central apnea is secondary to an already-coded condition. The sequencing rule matters: code the underlying condition first (for example, heart failure), then add G47.37. Using G47.31 when a cause is known is a coding error, and it can send the patient down the wrong testing pathway.

One pattern deserves its own mention: Cheyne-Stokes breathing (R06.3) is the waxing-and-waning breathing pattern — breaths that crescendo, decrescendo, and periodically stop — most often seen with heart failure. It has its own code outside the G47 family, and the G47.3 Excludes1 note means it is not coded together with a sleep apnea code for the same episode. If the chart describes Cheyne-Stokes breathing, R06.3 is the code, not G47.31.

G47.30: sleep apnea, unspecified — when it is the right code, and when it costs you

G47.30 is a placeholder, and placeholders have a short shelf life. It is the right code in exactly two situations: before the sleep study, when apnea is suspected but the type is genuinely unknown, and after a study that genuinely could not classify the apnea. In the pre-diagnostic stage it does useful work — it supports ordering the sleep study itself.

It becomes a problem when it stays on the record after the study has typed the apnea. A claim for CPAP filed under G47.30 is one of the most common preventable denials in sleep medicine, because the CPAP coverage policy accepts only G47.33 as the supporting diagnosis. The fix is simple but often missed: update the diagnosis on the claim the moment the sleep study report arrives, moving from G47.30 — or from a symptom code such as R06.83 for snoring — to the specific, confirmed code before the next service goes out.

The rare codes: G47.32, G47.34, G47.35, G47.36, G47.39

Most practices will never use these five codes, but knowing what they mean prevents the most common substitution errors.

G47.32, high altitude periodic breathing, describes the periodic breathing that appears at high altitude. It is altitude-specific and is not a variant of obstructive sleep apnea, even though the breathing pattern can look similar on a monitor.

G47.34, idiopathic sleep related nonobstructive alveolar hypoventilation, is a hypoventilation syndrome, not apnea: breathing becomes too shallow during sleep without a known cause. Do not substitute it for G47.33 — hypoventilation and apnea are distinct clinical entities with different treatments.

G47.35, congenital central alveolar hypoventilation syndrome, is rare and usually pediatric and genetic — historically called Ondine’s curse. Confirm against the record before using it; it is not a code for ordinary sleep apnea in a child.

G47.36, sleep related hypoventilation in conditions classified elsewhere, applies when hypoventilation is caused by another condition, such as obesity or neuromuscular disease. Like G47.37, it follows ICD-10 sequencing convention: the underlying condition is coded first. Do not confuse it with E66.2, morbid obesity with alveolar hypoventilation (obesity hypoventilation syndrome), which describes an obesity-driven mechanism.

G47.39, other sleep apnea, is the residual category — used for complex or mixed apnea that does not fit any more specific code. Confirm that nothing more specific applies before reaching for it.

How sleep apnea is diagnosed: the sleep study behind the code

Symptoms can suggest sleep apnea, but they cannot prove it. The NHLBI lists the warning signs as loud, frequent snoring, breathing that stops and starts, gasping or choking during sleep, and daytime sleepiness or waking up unrefreshed. Women more often report insomnia, fatigue, morning headaches, and mood symptoms rather than loud snoring. Only a sleep study confirms the diagnosis — and the study also produces the AHI number that the code and the coverage decision both depend on.

There are two testing routes. An attended, in-lab polysomnography (CPT 95810; with CPAP titration, 95811) is the gold standard: sensors on the scalp, face, chest, limbs, and a finger track brain waves, heart rate, breathing effort, and oxygen all night. A home sleep apnea test (CPT 95800, 95801, 95806, or Medicare codes G0398–G0400) is a simpler unattended device used at home, appropriate for otherwise uncomplicated adults whose symptoms suggest moderate-to-severe obstructive apnea.

The choice matters for coding, because the two routes do not share a covered-diagnosis list. Under Medicare’s billing article A57697, the home-test codes cover a narrow diagnosis group that includes G47.30 and G47.33 — and pointedly excludes G47.31, central sleep apnea. A home device generally cannot measure the respiratory effort signal needed to distinguish a central event from an obstructive one, so a patient whose picture suggests central apnea (Cheyne-Stokes pattern, heart failure history, opioid use) should go to a facility-based study instead. Ordering a home test for that patient risks both an inconclusive study and a coverage mismatch. And if a home test comes back negative, inconclusive, or technically inadequate, the American Academy of Sleep Medicine recommends an in-lab study — a negative home test does not always rule out apnea.

What Medicare requires for CPAP coverage

Here is where the code meets the money. Policy Article A52467 states directly that G47.33 is the only diagnosis code supporting PAP device coverage — and adds that the code alone is not sufficient by itself to assure coverage. The device, HCPCS E0601, is covered under Local Coverage Determination L33718 (Positive Airway Pressure Devices for the Treatment of Obstructive Sleep Apnea, CGS Administrators and Noridian Healthcare Solutions, effective January 1, 2024) only when all of the following are in the record.

Two practical notes. First, the 5–14 AHI tier is where most preventable CPAP denials start: a study result alone is enough to order the device clinically, but it does not satisfy the LCD unless the qualifying symptom or comorbidity is written into the same chart. Our guide to CPAP billing compliance walks through the adherence and re-evaluation documentation in detail. Second, if CPAP cannot be tolerated, an oral appliance is an alternative under a separate DME policy (LCD L33611) — still under G47.33, typically with documentation of CPAP intolerance or failure. Smaller travel devices, sometimes called micro-CPAP machines, still bill under the same E0601 code and the same coverage rules.

Why claims get denied — and what to do about it

The recurring denial patterns in sleep medicine are few, and all of them are preventable. For billers, the checklist is: never file a symptom-only code such as R06.83 (snoring) on a claim that needs a confirmed diagnosis; never leave G47.30 on a CPAP claim once the study has typed the apnea; never file the 5–14 AHI tier without the symptom or comorbidity documentation; and never let the day 31–91 re-evaluation slip — a claim with the right code and a missing re-evaluation note is still an audit risk. Sleep-medicine coding specialists flag exactly these errors as the most frequent reasons for denial.

For patients, a denial letter is not the end of the road. Start by reading the explanation of benefits and checking which diagnosis code was actually filed — if it says G47.30 or R06.83 after your sleep study confirmed obstructive apnea, the code is wrong and the clinic can correct it and resubmit. Keep your sleep study report: the AHI number is the evidence that decides coverage, and a request that cites it is far stronger than one that does not. If the denial stands, you can appeal through Medicare’s redetermination process, and your sleep clinic can supply an addendum documenting the symptoms or comorbidities that support the 5–14 tier.

One more sequencing point helps both sides. The G47.3 tabular note says to code any associated underlying condition alongside the apnea — for example, obstructive apnea with hypertension or heart failure carries both codes, with the underlying condition sequenced according to the encounter. The same “code the underlying condition too” logic applies across ICD-10: our guide to the mixed hyperlipidemia ICD-10 code shows how E78.2 is used alongside related diagnoses in exactly the same way.

Sleep apnea codes in children

Children use the same code as adults: G47.33 reads “obstructive sleep apnea (adult) (pediatric)”, so one code covers both age groups, and the sleep study evidence behind it is the same. The exception is newborns — obstructive sleep apnea of newborn is coded P28.3, and the Excludes1 note on G47.33 means the two are never reported together. Pediatric sleep studies have their own CPT codes (95782 for attended pediatric polysomnography, 95783 for the limited variant). The NHLBI-funded Childhood Adenotonsillectomy Trial (CHAT) provided the first rigorous evidence on tonsil surgery in children with sleep apnea, and adenotonsillectomy remains a common pediatric treatment when enlarged tonsils are the cause.

How to choose: getting the right code on your record

If you are a patient reading your own paperwork, or a coder staring at a chart, the decision follows the sleep study — never the symptoms alone. Questionnaires and prediction tools cannot diagnose sleep apnea; the American Academy of Sleep Medicine is explicit that they must not be used alone without polysomnography or home sleep apnea testing.

• No study yet, apnea suspected: G47.30, or a symptom code such as R06.83 for snoring. This supports ordering the study — not a CPAP machine.
• Study shows airway obstruction: G47.33, at any severity. Record the AHI in the chart; it drives coverage, not the code.
• Study shows brain-driven pauses with no underlying cause: G47.31, and route the patient to an in-lab study rather than a home test.
• Central pauses caused by heart failure or a neurologic disease: code the underlying condition first, then add G47.37.
• Study genuinely could not classify the apnea: G47.30 stays, and the chart should say why.

Two safety notes. First, tell your clinician about every medicine you take: long-term opioid pain medicines are a known cause of central sleep apnea, and the code — and the treatment — change when they are involved. Second, the NHLBI’s advice is simple and worth following literally: do not drive if you feel tired or sleepy. Excessive daytime sleepiness is itself one of the documented symptoms that supports coverage in the 5–14 AHI tier, and it is also a real safety risk.

The bottom line

The ICD-10 code for obstructive sleep apnea is G47.33 — one code for adults and children, at every severity. Primary central sleep apnea is G47.31; central apnea caused by another condition is G47.37, coded after that condition. G47.30, unspecified, is a placeholder for the time before the sleep study, not a final diagnosis. Severity lives in the AHI number, not in the code. And for CPAP, the code only opens the door: the sleep study result, the pre-test evaluation, the 31–91 day re-evaluation, and the adherence data are what actually get the device paid for. If a code on your bill does not match your sleep study, ask for it to be corrected — it is one of the easiest fixes in medical billing.

This article is for general education only and is not medical advice. ICD-10 codes change every October 1, and Medicare coverage rules vary by contractor and jurisdiction. Always confirm the current code set and your payer’s policy, and talk to your clinician or a certified coder about your specific situation.