Researchers studied nearly 1,600 married couples in Korea to understand how sleep apnea—a condition where breathing stops during sleep—affects muscle strength and size. They found that people with sleep apnea risk had weaker muscles and less muscle mass than those without the condition. Interestingly, when both partners had sleep apnea risk, they both experienced even greater muscle weakness. This suggests that sleep quality is important for keeping muscles healthy, and couples might benefit from getting screened and treated together for sleep problems.

The Quick Take

  • What they studied: Whether people with sleep apnea risk have weaker muscles and less muscle mass, and whether a partner’s sleep apnea affects the other partner’s muscle health
  • Who participated: 3,194 adults (1,597 married couples) in Korea, all age 40 or older. About 1,020 couples had complete muscle strength measurements. The group included both men and women from various backgrounds.
  • Key finding: People with high sleep apnea risk had significantly weaker grip strength and less muscle mass compared to those without sleep apnea risk. When both partners had sleep apnea risk, both experienced the worst muscle weakness—worse than if only one partner had the condition.
  • What it means for you: If you have signs of sleep apnea (like loud snoring or pauses in breathing), it may be affecting your muscle strength. Getting screened and treated could help protect your muscles. If you’re married or in a long-term relationship, your partner’s sleep health may also matter for your own muscle health.

The Research Details

This was a cross-sectional study, meaning researchers looked at information from couples at one point in time rather than following them over months or years. They used data from a large Korean health survey conducted in 2022-2023 that included detailed health information from thousands of people. Researchers measured sleep apnea risk using a simple questionnaire called the STOP-Bang score, which asks about snoring, tiredness, observed breathing stops, high blood pressure, age, neck size, and gender. They measured muscle strength using a handgrip test (squeezing a device as hard as possible) and estimated muscle mass using a special measurement called appendicular skeletal muscle mass. They then used statistical methods to see if sleep apnea risk was connected to weaker muscles, while accounting for other factors like age, weight, exercise habits, and health conditions.

This approach is important because it looks at couples as a unit rather than just individuals. Previous research focused on single people, but we spend much of our lives with partners who share our environment, sleep schedules, and lifestyle habits. By studying couples together, researchers could see if one person’s sleep problems somehow affected their partner’s muscle health—something that hadn’t been well studied before.

This study used a large, representative sample from a national health survey, which is a strength. However, because it’s cross-sectional, we can see that sleep apnea and weak muscles are connected, but we can’t prove that sleep apnea causes weak muscles—other factors could be involved. The study was limited to Korean adults and married heterosexual couples, so results may not apply equally to other populations or relationship types. The researchers adjusted for many other health factors, which strengthens the findings.

What the Results Show

The main finding was clear: people with high sleep apnea risk had significantly weaker grip strength and less muscle mass than those without sleep apnea risk. This was true for both men and women. The differences were statistically significant, meaning they were unlikely to be due to chance. When researchers looked at couples, they found that if only one partner had high sleep apnea risk, that person had weaker muscles. But when both partners had high sleep apnea risk, both experienced even greater muscle weakness than would be expected from just adding their individual risks together. This suggests that having a partner with sleep apnea risk might somehow make the problem worse for both people, possibly through shared lifestyle factors or stress.

The study found that partner effects (where one person’s sleep apnea affected the other’s muscles) were significant for husbands but not wives. This means that when a wife had high sleep apnea risk, it appeared to affect the husband’s muscle strength more than when a husband had high sleep apnea risk affected the wife’s muscles. The researchers also found that the connection between sleep apnea risk and weak muscles held true even after accounting for other factors like age, weight, physical activity, and existing health conditions.

Previous research has shown that sleep apnea is linked to weak muscles in individual people, but this is one of the first studies to look at how sleep apnea affects both partners in a couple. The findings support earlier research showing sleep apnea harms muscle health while adding new information about how couples’ health is connected. The couple-level effects are novel and suggest that sleep health might be more interconnected in relationships than previously understood.

This study has several important limitations. First, it’s cross-sectional, so we can’t prove sleep apnea causes weak muscles—only that they’re connected. Second, sleep apnea risk was measured using a questionnaire rather than a formal sleep study, which is less precise. Third, the study only included married heterosexual couples in Korea, so results may not apply to single people, same-sex couples, or people in other countries. Fourth, the researchers couldn’t measure all possible factors that might affect muscle health, so some connections might be explained by unmeasured factors. Finally, the study was conducted at one point in time, so we don’t know if these patterns continue over time.

The Bottom Line

If you snore loudly, experience pauses in breathing during sleep, or feel very tired during the day, talk to your doctor about sleep apnea screening. Getting tested and treated may help protect your muscle strength. If you’re in a relationship, encourage your partner to also get screened, as both partners’ sleep health appears to matter. Regular physical activity and strength training remain important for muscle health regardless of sleep apnea status. These recommendations are supported by this research but should be discussed with your healthcare provider.

This research is most relevant to adults over 40, especially those with risk factors for sleep apnea like snoring, high blood pressure, or being overweight. It’s also relevant to people concerned about maintaining muscle strength as they age. Couples should pay attention because the research suggests both partners’ sleep health matters. Healthcare providers should consider sleep apnea when assessing muscle weakness in middle-aged and older adults. People with existing muscle weakness or loss should discuss sleep quality with their doctors.

Sleep apnea’s effects on muscles likely develop over months to years, not overnight. If you get screened and treated for sleep apnea, improvements in muscle strength might take several weeks to months of consistent treatment and exercise. Don’t expect immediate changes, but consistent treatment combined with regular strength training should show benefits over time.

Want to Apply This Research?

  • Track your sleep apnea symptoms weekly (snoring frequency, daytime tiredness, witnessed breathing pauses) and measure grip strength monthly using a home grip strength meter. Record these alongside your exercise routine to see if sleep improvements correlate with stronger muscles.
  • Set a goal to address sleep apnea symptoms by scheduling a doctor’s appointment for screening, then track your treatment adherence (like using a CPAP machine if prescribed). Simultaneously, add 2-3 strength training sessions per week to your routine, logging which exercises you do and how many repetitions.
  • Create a long-term dashboard showing the relationship between sleep quality metrics (from a sleep tracker or app), sleep apnea symptom scores, and muscle strength measurements. Review monthly to see if improving sleep correlates with stronger grip strength and better muscle function in daily activities.

This research suggests an association between sleep apnea risk and reduced muscle strength but does not prove that sleep apnea causes muscle weakness. This information is for educational purposes and should not replace professional medical advice. If you suspect you have sleep apnea or are experiencing muscle weakness, consult with a healthcare provider for proper diagnosis and treatment. Sleep apnea is a serious medical condition that requires professional evaluation and treatment. Do not attempt to diagnose or treat sleep apnea without medical supervision.