Sleep & breathing · graded by use, four uses
CPAP for obstructive sleep apnea
Graded on: blood pressure and daytime sleepiness in adults with obstructive sleep apnea.
At a glance
CPAP is a machine that blows air through a mask at night to keep the throat open in sleep apnea. In many studies it made people less sleepy in the daytime and lowered blood pressure a little, mostly in people whose pressure was high. In four large studies it did not prevent heart attacks or strokes. Most people in those studies were not sleepy and used the machine about 3 hours a night.
The B is shared by three of the four uses graded on this record, each on its own evidence. The other one carries its own letter.
As studied, and the trials
Benning et al. (J Sleep Res, 2025; PMID 40254559) pooled 75 randomized trials: office systolic pressure 2.5 mmHg lower and nighttime systolic 3.5 mmHg lower than control. An individual-patient analysis of 9,434 people found the fall confined to those whose pressure was uncontrolled at the start (Pengo et al., Eur Respir J, 2025; PMID 39401854), and minimally sleepy patients showed no significant change (Bratton et al., Thorax, 2014; PMID 24947425). Blood pressure is a surrogate, so the letter stops at B.
As studied, and the trials
The maintenance of wakefulness test measures how long a person stays awake in a dim room, scored by instrument. CPAP improved it against sham in APPLES, most clearly at an apnea-hypopnea index above 30 (Kushida et al., Sleep, 2012; PMID 23204602), and by 2.1 minutes in pooled trials of mild to moderate sleep apnea (Marshall et al., Thorax, 2006; PMID 16467072). Held at B: the second objective test, the multiple sleep latency test, did not change in the same pooled trials, the effect in milder disease was small, and the trials behind the pooled figure are not itemized here.
As studied, and the trials
Bratton et al. (Lancet Respir Med, 2015; PMID 26497082) pooled 67 randomized trials: Epworth scores 2.5 points lower on CPAP than on inactive control, and the Cochrane review agrees (Giles et al., 2006; PMID 16437429). The effect was larger in sleepier patients. Self-reported, so the letter stops at B.
As studied, and the trials
Four randomized trials with hard endpoints The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. found no reduction in cardiovascular events: SAVE in 2,717 adults (McEvoy et al., N Engl J Med, 2016; PMID 27571048), ISAACC in 1,264 after acute coronary syndrome (Sanchez-de-la-Torre et al., Lancet Respir Med, 2020; PMID 31839558), RICCADSA in 244 (Peker et al., Am J Respir Crit Care Med, 2016; PMID 26914592) and a Spanish trial in 723 (Barbe et al., JAMA, 2012; PMID 22618923). Pooling SAVE, ISAACC and RICCADSA gave a hazard ratio How often an event happened in the treated group compared with the control group over the same period. A ratio of 0.80 means 20 percent fewer events. of 1.01 (Sanchez-de-la-Torre et al., JAMA, 2023; PMID 37787793). Lower event rates in people who used CPAP 4 hours or more appear only in on-treatment analyses, which lose the protection of randomization. The letter does not reach sleepy patients, who were largely excluded, or consistent all-night use, which the trials did not achieve.
Read the grade that matches your goal. How EBL grades by use →
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Blood pressure and daytime sleepiness in adults with obstructive sleep apnea.
Why this letter
Why this gradeThe reasoning, and what the grade does not cover.
Grade B on blood pressure (Benning et al., 2025; PMID 40254559) and on daytime sleepiness, both on the maintenance of wakefulness test (Kushida et al., 2012; PMID 23204602; Marshall et al., 2006; PMID 16467072) and on the Epworth scale (Bratton et al., 2015; PMID 26497082). Grade D on Route 2 Human randomized trials have been run and did not show benefit on the stated outcome. One of the two routes to the lowest letter on EBL's scale. for heart attack, stroke and cardiovascular death: four randomized trials and their pooled analysis found no reduction (PMIDs 27571048, 31839558, 26914592, 22618923, 37787793).
WHY NOT Ablood pressure is a surrogate and the Epworth scale is self-reported; the wakefulness test is instrument-scored, but the multiple sleep latency test did not change in the same pooled trials and the trials behind the pooled figure are not itemized here.
WHAT THIS GRADE DOES NOT COVERcardiovascular outcomes in sleepy patients who use CPAP all night, a group the large trials excluded or did not achieve.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
Evidence notes: randomized trial, meta-analysis A study that pools the numbers from several trials into one combined estimate.
Endpoint graded: Blood pressure and daytime sleepiness in adults with obstructive sleep apnea (surrogate)
Last reviewed: October 2026
The trial that would change this grade.
Positive trials of this shape from independent research groups would move this entry to A.
Why the current trials fall short
Wakefulness is the instrument-scored outcome closest to A. Separately, no cardiovascular trial has enrolled sleepy patients with full-night use, so the D for heart attack and stroke does not reach them.
Dose, form and timing
Apnea-hypopnea index on the device download and on retesting, nightly hours of use, the Epworth Sleepiness Scale, and home blood pressure.
Safety
Mask discomfort, dry mouth, nasal congestion and air swallowing are the common reasons people stop. Average use in the large cardiovascular trials was about 3 hours a night.
Grade history
How this letter has changedLatest: No. 364 · October 2026 · First graded.
CPAP now has its own record, graded by use. It lowered blood pressure modestly (Benning et al., J Sleep Res, 2025; PMID 40254559) and self-rated sleepiness (Bratton et al., Lancet Respir Med, 2015; PMID 26497082), both Grade B. Four large trials found no fall in heart attacks, strokes or cardiovascular deaths in patients who were mostly not sleepy and used CPAP about 3 hours a night (McEvoy et al., N Engl J Med, 2016; PMID 27571048; Sanchez-de-la-Torre et al., JAMA, 2023; PMID 37787793): Grade D on Route 2.PMID 40254559 PMID 26497082 PMID 27571048 PMID 37787793
Every change to a letter on this site is dated and published. The full evidence log →
Sources
- Citations
- Every paper cited on this page is matched to its PubMed record on every build.
- Retractions
- None of these papers is retracted or under a journal expression of concern. PubMed is checked again on every build.
- Read against the papers
- October 2026. By a language model (AI-assisted reading), not yet reviewed by a clinician.
- Outside review
- Not yet done. No reviewer outside EBL has checked this record.
What each of these checks can and cannot show: evidence integrity.
Primary evidence16 papers, each linked to its PubMed record.
Benning et al. (J Sleep Res, 2025; PMID 40254559), Bratton et al. (JAMA, 2015; PMID 26624827), Pengo et al. (Eur Respir J, 2025; PMID 39401854), Martinez-Garcia et al. (JAMA, 2013; PMID 24327037) and Bratton et al. (Thorax, 2014; PMID 24947425) on blood pressure; Kushida et al. (Sleep, 2012; PMID 23204602), Marshall et al. (Thorax, 2006; PMID 16467072), Giles et al. (Cochrane Database Syst Rev, 2006; PMID 16437429) and Bratton et al. (Lancet Respir Med, 2015; PMID 26497082) on sleepiness; McEvoy et al. (N Engl J Med, 2016; PMID 27571048), Sanchez-de-la-Torre et al. (Lancet Respir Med, 2020; PMID 31839558), Peker et al. (Am J Respir Crit Care Med, 2016; PMID 26914592), Barbe et al. (JAMA, 2012; PMID 22618923), Yu et al. (JAMA, 2017; PMID 28697252) and Sanchez-de-la-Torre et al. (JAMA, 2023; PMID 37787793) on cardiovascular events. Bradley et al. (Eur Respir J, 2024; PMID 39638419) set the observational Research that watches what people already do rather than assigning a treatment. It can show that two things travel together, not that one causes the other. and randomized cardiovascular evidence side by side: nine observational studies favored treatment and 12 randomized trials, which mostly excluded sleepy patients, did not.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("continuous positive airway pressure"[tiab] OR CPAP[tiab]) AND "obstructive sleep apnea"[tiab] AND ("cardiovascular events"[tiab] OR "blood pressure"[tiab] OR sleepiness[tiab] OR wakefulness[tiab]) AND (randomized controlled trial[pt] OR meta-analysis[pt])Disclosure
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
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