Research
Obstructive Sleep Apnea and Nocturnal Sweating
Obstructive sleep apnea (OSA) is an under-recognized cause of night sweats. In the Icelandic Sleep Apnea Cohort, one of the largest studies of the question, frequent nocturnal sweating (three or more nights per week) was reported by 30.6% of men and 33.3% of women with untreated OSA, compared with only 9.3% and 12.4% in a general-population sample. That is roughly a threefold higher prevalence. With full positive-airway-pressure (PAP) treatment, the prevalence dropped from 33.2% to 11.5% at two-year follow-up, essentially back to general-population levels. This page compiles the verified figures on OSA and nocturnal sweating. It is educational, not diagnostic advice.
By the Sweat Explained Editorial Team · Published 2026-07-19 · Last reviewed 2026-07-19 · Educational information, not medical advice.
Key statistics at a glance
30-33%
of untreated OSA patients report frequent nocturnal sweating (>=3 nights per week)
Arnardottir 2013 (Icelandic Sleep Apnea Cohort, n=822)
9-12%
of general-population adults report frequent nocturnal sweating
Arnardottir 2013 (n=703 controls)
3x
higher prevalence of frequent nocturnal sweating in untreated OSA patients vs the general population
Arnardottir 2013
33.2% → 11.5%
drop in frequent nocturnal sweating after full PAP treatment at 2-year follow-up
Arnardottir 2013
n=822
untreated OSA patients (all AHI >= 15) in the baseline Icelandic cohort
Arnardottir 2013
The Icelandic Sleep Apnea Cohort
The reference study is Arnardottir and colleagues (2013), published in BMJ Open. They compared 822 consecutively referred untreated moderate-to-severe OSA patients (apnea-hypopnea index of at least 15 events per hour) with 703 randomly selected general-population adults aged 40 and older from the Reykjavik area. Both groups answered the same core questionnaire, including a five-point frequency scale for nocturnal sweating.
"Frequent nocturnal sweating" was defined as sweating three or more nights per week. In the untreated OSA cohort, 30.6% of men and 33.3% of women reported this level of sweating, compared with only 9.3% of men and 12.4% of women in the general-population sample. The difference remained statistically significant after adjustment for demographic factors and was consistent across age bands from 40 to over 70 years.
Frequent nocturnal sweating: OSA vs general population
The same definition of "frequent nocturnal sweating" (three or more nights per week) applied to both cohorts. The gap between untreated OSA patients and the general-population sample is roughly threefold, and shrinks to the general-population level after successful PAP treatment.
| Group | Value |
|---|---|
| General population, men | 9.3% |
| General population, women | 12.4% |
| Untreated OSA, men | 30.6% |
| Untreated OSA, women | 33.3% |
| OSA on full PAP (2-year follow-up) | 11.5% |
Source: Arnardottir et al., BMJ Open 2013;3(5):e002795. Chart is an original rendering of the cited data.
What happens with treatment
The most striking finding of the Icelandic study was the change with treatment. Among OSA patients who used PAP for at least four hours per day, five or more days per week (their definition of "full PAP treatment"), the prevalence of frequent nocturnal sweating dropped from 33.2% at baseline to 11.5% at the two-year follow-up. That final figure is essentially the same as the general-population rate.
A smaller earlier study of 98 men with untreated OSA had already suggested a similar pattern: 34% reported nocturnal sweating at baseline, falling to 12% with PAP treatment. In both studies, PAP appears to specifically reduce the sweating symptom, not just improve daytime sleepiness.
Who, within OSA, is most likely to sweat at night?
In the Icelandic cohort, univariate analysis identified younger age as significantly associated with frequent nocturnal sweating among OSA patients. In multivariable models, associated factors included cardiovascular disease, hypertension, sleepiness, and insomnia symptoms.
| Factor | Direction / association |
|---|---|
| Younger age | Higher prevalence in younger OSA patients (p=0.003) |
| Cardiovascular disease (MI, heart failure, stroke) | Higher prevalence |
| Hypertension (diagnosed and treated) | Higher prevalence |
| Daytime sleepiness (higher Epworth score) | Higher prevalence |
| Insomnia symptoms | Higher prevalence |
| Body-mass index (BMI) | Not significantly different in the OSA cohort (p=0.08) |
Adapted from Arnardottir et al., BMJ Open 2013, Tables 1-2 and adjusted logistic-regression analyses.
Why OSA can cause night sweats
The likely mechanism, discussed in the Arnardottir paper and in earlier physiology work by the same group, is sympathetic nervous-system activation. Repeated apneic events cause intermittent hypoxia, arousals, and surges in sympathetic outflow, driving blood-pressure spikes and increased sweat-gland activity during the night. In a related study using objective electrodermal-activity measurement, patients with higher nocturnal sweat activity also had higher nocturnal blood pressure, and both fell together with PAP treatment.
In other words, night sweats in OSA are not just a nuisance; they may be a visible surface signal of the same autonomic and cardiovascular stress that makes untreated OSA a risk factor for hypertension and cardiovascular disease.
The clinical picture, from the data
Combining the numbers with the OSA literature, night sweats in obstructive sleep apnea have a recognizable pattern:
- Reported by roughly one third of untreated moderate-to-severe OSA patients, more than double the general-population rate.
- Distributed across all age bands from 40 to over 70, not confined to menopausal women.
- Typically described in earlier work as sweating around the neck and upper body during the night.
- Often accompanied by loud snoring, witnessed apneas or gasping, morning headaches, and daytime sleepiness.
- Responsive to effective PAP treatment: full PAP use returned prevalence to general-population levels at two-year follow-up.
- Under-recognized: only a minority of nocturnal-sweat patients mention the symptom, and clinicians do not routinely ask, so the connection with OSA is missed.
Methodology and limitations
The headline figures on this page come from Arnardottir ES et al., BMJ Open 2013;3(5):e002795, the largest published case-control and longitudinal cohort study of nocturnal sweating in obstructive sleep apnea to date. The Icelandic Sleep Apnea Cohort included 822 consecutively referred untreated patients with an apnea-hypopnea index of 15 or higher (666 men, 156 women, age 21-83); the general-population comparison cohort included 703 randomly selected Reykjavik-area residents aged 40 and older. Both groups completed the Basic Nordic Sleep Questionnaire and were assessed at the same clinic. PAP adherence was objectively measured from device data where available; full PAP use was defined as at least 4 hours per day for at least 5 days per week. Related mechanistic work (Arnardottir 2010, J Sleep Res 19(1 Pt 2):122-130) reported that objective electrodermal-activity measurements and blood pressure fell together with PAP treatment.
Limitations: nocturnal sweating was self-reported on a subjective 1-5 frequency scale, not objectively measured. Women were under-represented in the OSA cohort (156 of 822). The study was observational; the association between PAP and reduced sweating is strong and consistent with an earlier smaller study, but this is not a randomized controlled trial. Nothing on this page is diagnostic advice; anyone with symptoms consistent with sleep apnea (loud snoring, witnessed apneas, non-restorative sleep, daytime sleepiness, along with new nocturnal sweating) should be evaluated by a qualified clinician.
Frequently asked questions
- Does obstructive sleep apnea cause night sweats?
- In the largest study, untreated OSA was associated with about three times the general-population rate of frequent nocturnal sweating (30-33% vs 9-12%). Successful PAP treatment returned the rate to general-population levels, which is consistent with a causal role for OSA, though the study was observational rather than a randomized controlled trial.
- How common are night sweats in people with OSA?
- In the Icelandic Sleep Apnea Cohort of 822 untreated OSA patients, 30.6% of men and 33.3% of women reported nocturnal sweating three or more nights per week. That means roughly one in three untreated OSA patients has frequent nocturnal sweating.
- Do CPAP or other PAP treatments help?
- In the Icelandic cohort, frequent nocturnal sweating dropped from 33.2% to 11.5% among patients who used PAP at least 4 hours per day, 5 or more days per week over a 2-year follow-up. An earlier smaller study (n=98 men) reported a similar 34% to 12% drop with PAP treatment.
- Why does sleep apnea cause sweating at night?
- The proposed mechanism is sympathetic nervous-system activation. Repeated apneic events cause intermittent hypoxia, arousals, and surges in sympathetic outflow, driving blood-pressure spikes and increased sweat-gland activity during the night. Related work found objective electrodermal-activity measurements and blood pressure both dropped with PAP treatment.
- Who within OSA is most likely to have night sweats?
- In the Icelandic cohort, younger age was significantly associated with frequent nocturnal sweating among OSA patients. Cardiovascular disease, hypertension, sleepiness, and insomnia symptoms were also associated. BMI and gender were not significant independent predictors within the OSA group.
- Could my night sweats be sleep apnea?
- OSA is one of several important non-cancer, non-menopause causes of night sweats. If you have unexplained persistent night sweats along with loud snoring, witnessed pauses in breathing, non-restorative sleep, or excessive daytime sleepiness, discussing sleep apnea evaluation with a clinician is a reasonable step.
Sources
Primary peer-reviewed studies and official sources first, then reviews and institutional framing (secondary).
- Arnardottir ES, Janson C, Bjornsdottir E, Benediktsdottir B, Juliusson S, Kuna ST, Pack AI, Gislason T. Nocturnal sweating: a common symptom of obstructive sleep apnoea. The Icelandic sleep apnoea cohort. BMJ Open. 2013;3(5):e002795. Full text
- Arnardottir ES, Thorleifsdottir B, Svanborg E, Olafsson I, Gislason T. Sleep-related sweating in obstructive sleep apnoea: association with sleep stages and blood pressure. J Sleep Res. 2010;19(1 Pt 2):122-130. (secondary) PubMed
- Mold JW, Holtzclaw BJ, McCarthy L. Night sweats: a systematic review of the literature. J Am Board Fam Med. 2012;25(6):878-893 (context and prevalence comparisons). (secondary) Full text
- Smetana GW, et al. Persistent night sweats: diagnostic evaluation. Am Fam Physician. 2020;102(7):427-433. (secondary) AFP
How to cite this page
Sweat Explained. Obstructive Sleep Apnea and Nocturnal Sweating. Published 2026-07-19; last reviewed 2026-07-19. Available at: https://sweatexplained.com/research/sleep-apnea-night-sweats
Please cite the original studies for the underlying figures. Journalists are welcome to link to this page; the charts are original renderings of the cited data.