CPAP is the most effective treatment for obstructive sleep apnea when it is used. That last clause is the problem: studies estimate that almost half of people prescribed CPAP use it less than four hours a night, and insurers count you as nonadherent if you do not reach four hours a night on at least 70 percent of nights. If your machine sits on the nightstand, or you wear it faithfully and still wake up exhausted, this guide covers the difference between a CPAP that is not working and one that is not being used, the side effects that drive people away and how each is fixed, what to do about lingering tiredness, and the trials designed for people who cannot make CPAP work.
Is it not working, or not being worn enough?
Start with the numbers your machine records. Modern CPAP devices log hours of use, mask leak, and residual apnea events per hour, and your sleep clinic or the manufacturer's app can show them. Medicare and most insurers count you as adherent if you use CPAP at least four hours a night on 70 percent of nights during a 30 day stretch in the first 90 days, because four hours is roughly where studies start to see less daytime sleepiness, and more hours bring more benefit. If your hours are low, the machine cannot work, and the question is what is stopping you from wearing it. If your hours are good but the residual event count is still high, or you still feel unwell, the settings or the diagnosis need another look.
CPAP side effects, and what fixes each one
Dry mouth, dry nose, congestion. The most common complaint. Heated humidification, a heated tube, nasal saline, or a chin strap or full face mask for mouth breathers usually solve it.
Mask leaks, red marks, sore skin. Almost always a fit problem. Masks come in many styles and sizes, and a refit with a sleep technologist is often the single most useful step. Liners and different headgear help.
Feeling like you cannot breathe out, or swallowing air. Pressure that is too high, or that arrives too fast. Ramp settings, pressure relief on exhalation, or switching to an auto adjusting machine, which lowers pressure when it is not needed, are standard fixes. Swallowing air, which causes bloating, often responds to the same changes.
Claustrophobia and anxiety. Common and treatable. Desensitization, wearing the mask while awake for short periods, and brief behavioral programs increase adherence in studies. A smaller nasal pillow mask often helps.
Waking up to take it off, or not being able to fall asleep with it. Often a mix of the problems above plus insomnia, which CPAP does not treat. Treating the insomnia, usually with cognitive behavioral therapy, can be the thing that finally makes CPAP tolerable.
None of these fixes requires giving up on CPAP, and most are made in one visit. Do not change pressure settings yourself; they are set from your sleep study.
Still tired after CPAP?
If your hours are good, your leak is low, and you still feel exhausted, several things are worth checking. Residual sleep apnea, where the pressure is no longer enough, shows up in the machine data. Insufficient sleep time, insomnia, shift work, depression, and medicines that cause drowsiness are common and separate from apnea. Some people have persistent daytime sleepiness despite well treated apnea, and a few medicines are approved for it, including modafinil, armodafinil, and solriamfetol, approved in 2019. And a minority of people have central sleep apnea, in which the brain rather than the airway is the problem and standard CPAP is often not enough on its own; the machine data and a repeat sleep study can tell. Our guide explains how sleep studies work.
When CPAP truly is not an option
Some people cannot tolerate CPAP after every fix has been tried, and sleep medicine now has a real answer for them rather than a shrug. Approved options include custom oral appliances, most often used for mild to moderate apnea and also an option for people who cannot use CPAP, hypoglossal nerve stimulation, an implant approved since 2014 that moves the tongue forward with each breath and has now been placed in more than 100,000 people, tirzepatide since December 2024 for moderate to severe apnea in people with obesity, and surgery in selected cases. A pill that acts on the airway muscles is under FDA review, with a decision expected in early 2027. Our sleep apnea treatment trials page covers each of these and what is being tested. Whichever route you take, untreated moderate to severe apnea raises blood pressure and the risk of heart disease and stroke, so the goal is treatment you will actually use, not a particular device.
Trials built for people who cannot use CPAP
Because CPAP intolerance is so common, it is a defined entry criterion in a growing number of studies. Trials compare oral appliances with nerve stimulation in people who failed or declined CPAP; test newer two sided nerve stimulators; study whether weight loss medicines improve results after an implant; and test apps designed to raise CPAP use for people who want to keep trying. Drug trials for sleep apnea often require that you are not currently using CPAP or are willing to pause it, which makes people struggling with the mask natural candidates. Every listing states its own rules, and study teams coordinate with your sleep doctor.
Studies recruiting now for exactly this situation
The OSANOVA study at Washington University compares a custom oral appliance with hypoglossal nerve stimulation in adults with moderate to severe apnea who failed, declined, or could not tolerate CPAP. A study of the Genio two sided nerve stimulator follows adults 22 and older who are intolerant of or failed CPAP, with an apnea hypopnea index (AHI) between 15 and 65. The device is already FDA approved, so the implant itself goes through your insurance. And for people who want to make CPAP work, a Mayo Clinic study tests a smartphone app designed to raise use to six hours a night in adults newly diagnosed and starting CPAP, using a phone app and a wrist sensor. Applying takes about 5 minutes, and more studies are on our obstructive sleep apnea clinical trials page.
Common questions
Why is my CPAP not working? Usually one of three things: it is not being used enough hours because of a fixable side effect, the pressure or mask no longer fits your needs, or something other than apnea is causing your tiredness. The machine's own data, reviewed with your sleep clinic, usually shows which.
What are the most common CPAP side effects? Dry mouth or nose, congestion, mask leaks and skin marks, difficulty exhaling against the pressure, swallowing air and bloating, and claustrophobia. Each has a standard fix, most often humidification, a mask refit, or a pressure adjustment.
What if I cannot sleep with CPAP at all? Tell your sleep clinic rather than quietly stopping. Desensitization, a different mask, an auto adjusting machine, and treating insomnia alongside CPAP all help many people. If none does, approved alternatives and trials for CPAP intolerant patients exist.
Do I qualify for a sleep apnea trial if I stopped using CPAP? Often, yes. Many trials specifically enroll people who could not tolerate or declined CPAP, and some drug trials require that you are not using it. Many trials ask for a recent sleep study, often from the past one to two years, and some accept only moderate to severe apnea.
See sleep apnea clinical trials recruiting now
Browse open studies, filter by location, and apply in about 5 minutes: Obstructive Sleep Apnea Clinical Trials