Researchers studied 451 older adults to see if a simple sleep questionnaire could help identify people with low vitamin D. They found that people with signs of sleep apnea—like a larger neck size, higher weight, and daytime tiredness—were more likely to have vitamin D deficiency. This discovery suggests doctors could use a quick sleep screening tool to spot patients who need vitamin D testing. The findings are important because both sleep problems and low vitamin D are common in older adults and can affect overall health.

The Quick Take

  • What they studied: Whether a simple sleep questionnaire designed to find sleep apnea risk could also identify people with low vitamin D levels
  • Who participated: 451 older adults (65+ years old) from a health study at a major hospital in Taiwan who completed sleep questionnaires and had their vitamin D levels tested
  • Key finding: Older adults with certain sleep apnea warning signs—especially a larger neck size, higher body weight, and daytime sleepiness—were significantly more likely to have low vitamin D levels
  • What it means for you: If you’re older and have sleep problems or daytime tiredness, asking your doctor to check your vitamin D levels may be worthwhile. However, this study shows a connection, not proof that one causes the other, so talk to your healthcare provider about whether testing makes sense for you.

The Research Details

This was a prospective observational study, which means researchers followed a group of people over time and observed what happened without changing their behaviors. The 451 older adults completed the STOP-Bang questionnaire—a simple 8-question tool that asks about snoring, tiredness, observed breathing stops, high blood pressure, body mass index, age, neck size, and gender. These questions help doctors identify who might have sleep apnea. All participants also had blood tests to measure their vitamin D levels. Researchers then looked for patterns between the questionnaire answers and vitamin D results.

The STOP-Bang questionnaire was originally created to screen for obstructive sleep apnea (OSA), a condition where breathing repeatedly stops during sleep. However, researchers noticed that sleep apnea and vitamin D deficiency share many of the same risk factors, like obesity, older age, and high blood pressure. This made them wonder if the same screening tool might help identify both conditions.

This research approach is valuable because it’s practical and efficient. Rather than developing a completely new screening tool, researchers tested whether an existing, simple questionnaire could serve double duty. If the connection holds up in future studies, doctors could use one quick screening tool to identify patients who need testing for both sleep problems and vitamin D deficiency. This could lead to earlier detection and treatment of both conditions, which is especially important for older adults who are at higher risk for complications.

This study has several strengths: it included a reasonably large group of 451 participants, used standardized questionnaires and blood tests, and was conducted at a reputable medical center. However, it’s observational rather than experimental, meaning it shows associations but cannot prove that one condition causes the other. The study was also conducted in Taiwan, so results may not apply equally to all populations. Additionally, the study is relatively new (2025), so the findings need confirmation from other research groups before drawing firm conclusions.

What the Results Show

The study found a clear inverse relationship between vitamin D levels and body mass index (BMI)—meaning as weight increased, vitamin D levels decreased. This connection was statistically significant, suggesting it wasn’t due to chance. Women were more likely than men to have vitamin D deficiency. Participants with larger neck circumferences—one of the key measurements in the STOP-Bang questionnaire—were significantly more likely to have low vitamin D.

People who reported daytime sleepiness or tiredness had notably lower vitamin D levels compared to those without daytime tiredness. This finding is particularly interesting because daytime sleepiness is one of the main symptoms of sleep apnea. The combination of these factors suggests that the STOP-Bang questionnaire’s components may help identify vitamin D deficiency risk.

The research confirmed that vitamin D deficiency and sleep apnea risk factors overlap considerably in older adults. The study also highlighted that female sex was an independent risk factor for vitamin D deficiency, which aligns with previous research showing women are more prone to vitamin D insufficiency. The findings suggest that multiple factors work together—someone with a larger neck size, higher weight, and daytime tiredness would be at particularly high risk for vitamin D deficiency.

Previous research has shown that both vitamin D deficiency and sleep apnea are common in older adults and share risk factors like obesity and age. However, most studies have examined these conditions separately. This research is novel because it specifically investigates whether the screening tool for one condition could identify the other. The findings align with existing knowledge about obesity and vitamin D (heavier people tend to have lower vitamin D), but the specific connection to sleep apnea screening parameters is relatively new.

The study has several important limitations. First, it’s observational, so it shows that these factors are connected but doesn’t prove that one causes the other. Second, the study was conducted in Taiwan with a specific population, so the results may not apply equally to people in other countries or different ethnic backgrounds. Third, the study doesn’t explain why these connections exist—it just documents that they do. Finally, the study doesn’t follow people over time to see if low vitamin D actually leads to worse sleep problems or vice versa. Researchers themselves note that more studies are needed to understand the cause-and-effect relationship.

The Bottom Line

If you’re an older adult with signs of sleep problems (snoring, daytime tiredness, witnessed breathing pauses), consider asking your doctor about vitamin D testing. This is a low-risk, simple blood test that could identify a treatable deficiency. If you do have low vitamin D, your doctor may recommend supplements or increased sun exposure. However, these recommendations are based on observed connections, not definitive proof, so discuss your individual situation with your healthcare provider. Confidence level: Moderate—the findings are interesting and worth discussing with your doctor, but more research is needed.

This research is most relevant to older adults (especially those over 65), people with sleep problems or daytime sleepiness, people with higher body weight, and women. If you have a larger neck circumference or have been told you might have sleep apnea, this information is particularly relevant. However, younger people without sleep concerns or vitamin D risk factors may not need to take immediate action based on this single study. Anyone with existing health conditions should discuss these findings with their doctor rather than self-diagnosing.

If vitamin D deficiency is identified and treated with supplements, most people begin feeling benefits within 4-8 weeks, though full effects may take 2-3 months. Sleep improvements from addressing vitamin D deficiency may take longer—typically 2-3 months or more. However, individual responses vary significantly, and some people may not notice dramatic changes. Consistent monitoring over several months is important to assess whether treatment is working.

Want to Apply This Research?

  • Track daytime sleepiness on a scale of 1-10 daily, along with weekly vitamin D supplement intake (if prescribed) and sun exposure time. Note any changes in sleep quality or daytime energy levels over 8-12 weeks.
  • If your doctor recommends vitamin D supplementation, set a daily reminder to take your supplement at the same time each day (ideally with a meal for better absorption). Also, aim to get 10-30 minutes of midday sun exposure several times per week, weather permitting, as sunlight helps your body produce vitamin D naturally.
  • Use the app to log weekly energy levels, sleep quality ratings, and supplement adherence. After 8-12 weeks, compare your baseline scores to current scores. Schedule a follow-up blood test with your doctor at 8-12 weeks to measure whether vitamin D levels have improved. Continue tracking for at least 3 months to assess whether vitamin D supplementation affects your sleep quality and daytime tiredness.

This research shows a connection between sleep apnea risk factors and vitamin D deficiency in older adults, but it does not prove that one condition causes the other. The findings are based on a single observational study and should not be used for self-diagnosis. If you suspect you have sleep apnea, vitamin D deficiency, or related health concerns, please consult with a qualified healthcare provider who can perform proper testing and recommend appropriate treatment. Do not start, stop, or change any supplements or medications without medical guidance. This information is for educational purposes only and is not a substitute for professional medical advice.