There is a question that comes up in clinical practice more often than it probably should: could someone have obstructive sleep apnea and not know it — not because they haven’t been evaluated, but because the evaluation missed it?

The answer, more often than most people realize, is yes.

Sleep apnea is one of the most common sleep disorders in adults, and it is also one of the most underdiagnosed. Part of the reason is that the clinical picture most clinicians carry — and most screening tools are built around — reflects only one version of how the condition presents. When someone doesn’t fit that version, the diagnosis can be delayed for years.

The Classic Picture — and Why It Falls Short

The textbook case of obstructive sleep apnea is an overweight, middle-aged man who snores loudly and falls asleep during the day. That picture is real. It is also incomplete.

Women with sleep apnea frequently present differently. Instead of loud snoring and obvious daytime sleepiness, they may report insomnia, fatigue, morning headaches, mood changes, or difficulty concentrating. Some don’t know whether they snore at all, particularly if they sleep alone. During and after menopause, the risk of sleep apnea increases significantly — even as the symptoms are often attributed to hormonal changes, stress, or the ordinary effects of aging.

Women are also more likely to experience breathing disturbances that occur predominantly during REM sleep, the stage when the upper airway is most vulnerable and when muscle tone is lowest. This matters clinically because REM-predominant sleep apnea can be less obvious on certain tests, and because the symptoms it produces — fragmented sleep, fatigue, mood disturbance — are easier to attribute to other causes.

The same atypical presentation can appear in people of normal weight, in younger adults, and in anyone whose daytime sleepiness is blunted by stimulant medications. If someone is taking a wakefulness-promoting medication — Concerta for ADHD, for example — one of the most recognizable symptoms of sleep apnea may simply not be visible. They may be functioning well, exercising, working long hours, and rarely feeling sleepy. That does not mean they are sleeping well.

The Limits of Home Sleep Testing

Home sleep apnea tests have become the standard first-line evaluation for suspected OSA, and they are useful. They are also limited in ways that matter for the patients most likely to be missed.

Most home devices measure airflow, respiratory effort, and oxygen saturation. What they typically do not measure are brain waves, sleep stages, or the microarousals that signal breathing-related disruptions without a full awakening. As a result, they may underestimate the severity of sleep apnea — particularly in people with fragmented sleep, REM-predominant breathing disturbances, or a relatively low apnea-hypopnea index that still produces significant sleep disruption.

A negative home study does not rule out sleep apnea. The American Academy of Sleep Medicine recommends an in-laboratory polysomnogram when a home test is negative or inconclusive and clinical suspicion remains. That recommendation exists precisely because a normal-looking home test is not always the final answer.

Three Things Worth Keeping in Mind

Tired isn’t the same as sleepy. Fatigue and sleepiness are distinct experiences, and clinicians and patients sometimes use them interchangeably. Someone can feel profoundly exhausted without the urge to fall asleep that characterizes pathological sleepiness. The absence of daytime sleepiness — especially in someone on a stimulant medication — does not rule out sleep apnea.

A negative home test isn’t always the final word. When the clinical picture is suggestive — fragmented sleep, unrefreshing sleep, REM-predominant symptoms, risk factors that don’t fit the classic profile — further evaluation is warranted even after a negative home study.

Insomnia and sleep apnea frequently coexist. The combination has a name: COMISA, for comorbid insomnia and sleep apnea. Research suggests that 30 to 50 percent of patients presenting for OSA treatment also report clinically significant insomnia. CBT-I addresses the insomnia effectively, but coexisting sleep apnea requires its own evaluation and treatment. Treating one does not resolve the other.

APA Citations

Theorell-Haglöw, J., Lindberg, E., & Janson, C. (2006). What are the important risk factors for daytime sleepiness and fatigue in women? Sleep, 29(6), 751–757. https://doi.org/10.1093/sleep/29.6.751

Kapsimalis, F., & Kryger, M. H. (2002). Gender and obstructive sleep apnea syndrome, part 1: Clinical features. Sleep, 25(4), 412–419. https://doi.org/10.1093/sleep/25.4.412

Punjabi, N. M. (2008). The epidemiology of adult obstructive sleep apnea. Proceedings of the American Thoracic Society, 5(2), 136–143. https://doi.org/10.1513/pats.200709-155MG

Sweetman, A., Lack, L., McEvoy, R. D., Smith, S., Catcheside, P. G., Antic, N. A., Chai-Coetzer, C. L., Douglas, J., O’Grady, A., Dunn, N., Robinson, J., Paul, D., & Clements, J. (2019). Bi-directional relationships between co-morbid insomnia and sleep apnea (COMISA). Sleep Medicine Reviews, 45, 37–46. https://doi.org/10.1016/j.smrv.2019.03.005

American Academy of Sleep Medicine. (2017). AASM clinical practice guideline for the diagnostic testing for adult obstructive sleep apnea. https://aasm.org/resources/clinicalguidelines/diagnostic-testing-OSA-adults.pdf