If you’re being treated for obstructive sleep apnea (OSA) yet feel like you’re still walking through a fog, you aren’t alone. Up to 58 percent of people with OSA experience excessive daytime sleepiness (EDS), and it can persist even when treated with continuous positive airway pressure (CPAP) therapy.
Sleep success comes down to the two Qs: quality and quantity, says Raj Dasgupta, MD, a pulmonary critical care and sleep medicine specialist at Huntington Health in Pasadena, California. In other words, you may be getting enough hours of sleep, but you’re not reaching the deeper, restorative stages of sleep, for which a number of reasons could be to blame.
1. Your CPAP Needs a Professional Adjustment
Even if you wear your CPAP mask all night, you may not be getting the full benefit if the mask fit or pressure settings aren’t quite right. Dr. Dasgupta says 30 to 50 percent of people with OSA have a suboptimal CPAP setup during their first year of treatment, which can make therapy less effective. What’s more, long-term CPAP adherence may be as low as 30 percent.
CPAP therapy works by providing what Dasgupta calls a “pneumatic splint,” a steady flow of pressurized air that keeps the airway open during sleep. When that splint is compromised by mask leaks or insufficient pressure, the airway can still partially or fully collapse. This collapse leads to intermittent hypoxia (drops in oxygen levels), which keeps the body in a chronic state of physiological stress.
Signs your CPAP therapy may not be optimized include waking with a dry mouth, red marks on your face, snoring, frequent nighttime awakenings, morning headaches, or persistent EDS. A bed partner may also hear the machine “hissing,” that can signal a poor mask seal.
The Solution: Review Your CPAP Data With Your Doctor
Don’t change settings on your own; instead, talk with your sleep specialist, who can fine-tune pressure, address mask leaks, or suggest comfort features like ramp or pressure relief. A nasal pillow mask may also be easier to tolerate for some people than a full-face mask, says Dasgupta.
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Sleep disorders often coexist. About 50 percent of people with a sleep disorder have one or more others, such as OSA, insomnia, restless leg syndrome, or EDS.
“The most common combination I see in my clinic is insomnia and OSA,” says Dasgupta. “Both have to be addressed, as treating insomnia won’t help OSA, and the treatment for OSA definitely won’t help insomnia.”
The Solution: Request a Sleep Study
It’s easier than ever to get evaluated for multiple sleep disorders, says Dasgupta. “Some home sleep tests are as simple as wearing a ring on your finger or placing a small patch on your forehead,” he says. “You sleep in your own bed, at your own time, with your own pillow.” These tests can help your doctor identify coexisting sleep disorders and determine which lifestyle changes, therapies, or medications may improve your symptoms.
3. Your Sleep Hygiene Needs Help
Even the most well-fitted CPAP mask can’t fully counteract poor sleep habits. Inconsistent bedtimes and wake times are linked with EDS, and alcohol (especially before bed) can worsen airway blockages and fragment sleep, reducing its restorative quality.
“I’m a big believer in sleep hygiene,” says Dasgupta. “The bedroom needs to be dark, quiet, and cool. Limit screentime before bed. [And] we shouldn't drink alcohol or caffeine late in the day.”
The Solution: Create New Bedtime Habits
Because OSA already disrupts deep, restorative sleep, maintaining strong sleep hygiene is especially important in people with the condition. “Optimizing sleep habits is essential,” says Priya Jaisinghani, MD, who specializes in endocrinology, obesity medicine, and diabetes at NYU Langone Health in New York City.
“Limiting late caffeine and alcohol [consumption], keeping consistent sleep and wake times, and getting morning light exposure can improve sleep quality,” she says.
Consider keeping a sleep journal and share it with your doctor to assess any sleep habits that can be improved.
4. You’re Paying Off Sleep Debt
OSA can create chronic sleep debt, says Dasgupta. Repeated awakenings throughout the night prevent you from reaching deep, restorative stages of sleep, so your body consistently gets worse-quality rest than it needs. Over time, this deficit builds up, leaving you foggy, slow to react, and prone to poor judgment.
The consequences of this debt go beyond feeling tired, says Dasgupta, and include physical and mental health complications and a much higher risk of accidents.
The Solution: Treat Your Apnea — and Be Patient
“The solution for untreated OSA and sleep debt involves treating the apnea first, often with CPAP therapy, oral appliances, referral to an otolaryngologist, and lifestyle changes to allow [for the] appropriate quantity and quality [of] sleep,” says Dasgupta. “Then repay the sleep debt with consistent bedtimes, good sleep hygiene, and a regular schedule to gradually restore energy and function.”
5. Your Mental Health Is Interfering
OSA often overlaps with mental health conditions. About 11 to 18 percent of people with depression have OSA, and those at high risk for sleep apnea are more likely to experience simultaneous mental health conditions, as well as develop new ones. Certain antidepressants can also worsen OSA symptoms, says Dasgupta.
It’s the ultimate “chicken or the egg” scenario, he says. “Is it because of your depression that you're not sleeping at night, or is it because you can't fall asleep at night that you're depressed?” This cycle is hard to break because untreated OSA can make depression worse.
Solution: Take a Multidisciplinary Approach
Dasgupta recommends coordinating care between your sleep specialist and mental healthcare provider to ensure that your treatments and medications are working together to support both your sleep and mental health.
6. You Need Supplementary Medicine
Sometimes, EDS can be a by-product of long-term sleep apnea. Even when your CPAP is working well, years of interrupted sleep and drops in oxygen can affect the “wiring” in your brain, in both gray matter (which processes information) and white matter (which connects different brain regions). This damage can leave you feeling foggy or tired during the day.
The Solution: Ask About Add-On Treatment
If you’ve been using your CPAP for most of the night for several months and still find yourself dozing off during meetings, ask your specialist whether “add-on” wakefulness-promoting medications may be right for you. Medications like armodafinil, modafinil, and solriamfetol can help, as they boost the brain chemicals that help you stay alert.
7. You May Have Treatment-Emergent Central Sleep Apnea
In rare cases, treating OSA can uncover a different issue called treatment-emergent central sleep apnea (TECSA), formerly known as complex sleep apnea. TECSA occurs when therapy successfully opens your airway, but the brain doesn’t consistently send the signal to breathe. In other words, the “plumbing” is fixed, but the “wiring” is temporarily out of sync.
TECSA is most often identified with CPAP therapy, but it can also occur after oral appliance therapy or nasal surgery. People sometimes describe feeling like they’re “fighting” their CPAP machine, or they notice that their daytime sleepiness actually worsens after starting treatment.
The Solution: Get Checked for Central Sleep Apneas
The good news is that TECSA often improves on its own as the brain adapts, usually within a few weeks of consistent therapy. If you’re still exhausted after that adjustment period, ask your doctor about an in-lab sleep study to check for central apneas.
If the breathing pauses don’t resolve, a different type of device may help. Unlike standard CPAP therapy, advanced machines such as BiPAP or adaptive servo-ventilation (ASV) are designed to step in and trigger a breath when your brain doesn’t, helping restore normal breathing and better sleep.
8. Your Weight Management Medication Is Still Working
If you’re taking a weight-management medication like tirzepatide (Zepbound), which is approved for the treatment of severe-to-moderate OSA in people with obesity, ongoing daytime sleepiness may simply mean your treatment hasn’t had enough time to work yet. These medications are started at low doses with gradual increases, so meaningful weight loss — and the relief it can bring to your airway — occurs steadily.
“The recommended maintenance doses of Zepbound for moderate-to-severe OSA are 10 milligrams (mg) and 15 mg weekly, and it may take several months of gradual dose escalation to reach these levels, depending on individual tolerance and response,” says Dr. Jaisinghani.
As weight comes down, pressure on the airway decreases, which can reduce nighttime breathing events and improve daytime alertness. Until then, it’s common to still feel tired even if you’re doing everything right.
The Solution: Stay the Course, Check In With Your Doctor
Give your medications time to work, and check in with your doctor regularly, especially when starting a new treatment.
“While many patients experience meaningful improvement and nearly half may achieve remission, not everyone may have complete resolution, and some residual disease can persist,” says Jaisinghani. “If daytime sleepiness persists, it’s important to update and follow up with a provider for continued evaluation.”
The Takeaway
In people with OSA, persistent sleepiness may be caused by an improperly fitted CPAP mask or incorrect pressure settings, which can allow for continued airway collapse and oxygen drops despite regular use.
Up to 50 percent of OSA patients have multiple sleep disorders, such as insomnia or restless leg syndrome, or overlapping mental health issues like depression. You may also need supplemental treatment for conditions such as central sleep apnea or to handle the effects of long-term OSA.
Sometimes all you need is patience. Weight loss drugs need time to work before they have a strong effect on your sleep quality, and even people using a CPAP may have sleep debt to overcome.
Good sleep hygiene is still critical to the success of any OSA therapy.
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Resources
Lal C et al. Excessive Daytime Sleepiness in Obstructive Sleep Apnea. Mechanisms and Clinical Management. Annals of the American Thoracic Society. May 2021.
Qiao M et al. Long Term Adherence to Continuous Positive Airway Pressure in Mild Obstructive Sleep Apnea. BMC Pulmonary Medicine. September 1, 2023.
Kim B et al. Restless Legs Syndrome in Patients With Obstructive Sleep Apnea: Association Between Apnea Severity and Symptoms of Depression, Insomnia, and Daytime Sleepiness. Sleep Medicine. May 2024.
Yared L et al. Sleep Hygiene, Daytime Sleepiness, and Coping Mechanisms Amongst US Adults. Cureus. September 20, 2023.
Ogbu I et al. Sleep Disordered Breathing and Neurocognitive Disorders. Journal of Clinical Medicine. August 23, 2024.
Chen X et al. Prevalence and Risk Factor of Obstructive Sleep Apnea in Depression: An Observational Retrospective Study. Frontiers in Psychology. April 6, 2025.
Kendzerska T et al. Obstructive Sleep Apnea Risk and Mental Health Conditions Among Older Canadian Adults in the Canadian Longitudinal Study on Aging. Psychiatry. December 26, 2025.
Zhang J et al. Treatment-Emergent Central Sleep Apnea: A Unique Sleep-Disordered Breathing. Chinese Medical Journal. September 30, 2020.
Malholtra A et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. The New England Journal of Medicine. June 21, 2024.
Abhinav Singh, MD, is a board-certified sleep medicine specialist and the medical director of the Indiana Sleep Center. He is also an associate clinical professor at Marian University College of Osteopathic Medicine in Indianapolis, where he developed and teaches a sleep medicine rotation.
Dr. Singh’s research and clinical practice focus on sleep disorders, including excessive daytime sleepiness, narcolepsy, sleep apnea, insomnia, and sleep education.
Singh is a peer reviewer for the Journal of Clinical Sleep Medicine, Sleep Health (from the National Sleep Foundation) and the Journal of Sleep Disorders: Treatment and Care, and is coauthor of the book Sleep to Heal: 7 Simple Steps to Better Sleep. He has received several Top Doctor recognitions and is the sleep specialist for the Indiana Pacers NBA team.
He lives in the Indianapolis area and enjoys music production and racquet sports.
Susan Jara is a health communications strategist and writer with more than 15 years of experience transforming complex medical information into clear, accurate, and engaging content for diverse audiences of patients and caregivers. She specializes in patient education, health literacy, and SEO-driven content strategy, with expertise across chronic disease, mental health, addiction, arthritis, autoimmune conditions, and wellness.
Susan holds a bachelor’s degree in journalism and media studies from New York University’s Gallatin School of Individualized Study. Her career includes leadership roles at the Global Healthy Living Foundation and Health Monitor Network, where she developed multichannel health content across web, email, podcasts, video, social media, and print. Susan's work reaches millions of readers each year, and she collaborates with leading healthcare providers, researchers, advocacy groups, and industry partners to create resources that reach millions of readers each year.
