Nationwide monitoring data from wearable smart device reveals high temperatures may worsen sleep apnea.
image: Overall lag structure in the effects of extreme high temperature on OSA exacerbation (a), AHI (b) and MinSpO2 (c) over 0 to 7 d. The effects were calculated by comparing the extreme high temperature (30.3 ℃, the 97.5th percentile) to the referent temperature (-5.2 ℃). Solid lines = mean percent change (a) or absolute change (b and c); shaded areas = 95% confidence intervals. AHI: apnea-hypopnea index; MinSpO2: minimum oxygen saturation; OSA: obstructive sleep apnea.
Credit: ©Science China Press
This study was led by Professor Renjie Chen, Professor Haidong Kan (School of Public Health, Fudan University) and Professor Yutao Guo (Department of Pulmonary Vessel and Thrombotic Disease, Sixth Medical Center, Chinese PLA General Hospital). This national longitudinal study quantitatively assessed the relationship between daily temperature and sleep apnea-related indicators based on wearable health devices.
Obstructive sleep apnea (OSA) is a serious sleep disorder that can affect sleep quality and can result in metabolic disorders, neurocognitive impairment, cardiovascular diseases (such as hypertension), and even deaths. The prevalence of OSA was estimated to be 24% globally and 23.6% in China, resulting in a substantial disease burden. Therefore, identifying the risk factors for OSA is crucial for alleviating the burden of OSA-related disease.
Evidence suggests that ambient temperature may influence OSA incidence and progression. However, most studies have assessed OSA severity using only the apnea-hypopnea index (AHI). Additionally, previous studies were conducted in single cities or sleep centers with small sample sizes, limiting the generalizability of the findings. Furthermore, almost all prior studies used a cross-sectional design with one-night screenings to evaluate OSA, which may lead to diagnostic misclassification or errors, adding considerable uncertainty to the observed associations. Traditional OSA monitoring typically requires polysomnography, which is expensive, requires professional operation, and disrupts normal sleep behavior, making it unsuitable for real-world sleep health investigations.
To address these issues, researchers conducted a longitudinal study using sleep apnea screening technology from smart wearable devices. The study included 6,232,056 days of sleep monitoring data from 51,842 participants with moderate to severe OSA risk from 313 Chinese cities. The aim was to investigate the short-term effects of ambient temperature on OSA exacerbation, AHI, and minimum oxygen saturation (MinSpO2).
The results showed that the effects of the extreme high temperatures on all the three indicators were present on the same day (lag 0 d) and disappeared immediately at lag 1 d or more. This suggests that higher temperatures immediately exacerbate OSA, increase AHI and decrease MinSpO2 without lag effect. Therefore, people should pay attention to high-temperature warnings and take high-temperature adaptive measures (e.g., air conditioning) to reduce the adverse effects of high temperatures on OSA.
The exposure–response curves showed that the relationships between ambient temperature and OSA exacerbation, apnea-hypopnea index (AHI), and minimum oxygen saturation (MinSpO2) were almost linear. For each 10 ℃ increase in temperature, the odds of OSA exacerbation would increase 8.4% (95% CI: 7.6% to 9.3%), AHI would increase by 0.70 events/h (95% CI: 0.65 to 0.76), and MinSpO2 would decrease by 0.18% (95% CI: 0.16% to 0.19%).
To investigate the effect of a shorter exposure on the same night, researchers also evaluated the association of the 12-h average temperature prior to the time of awakening (roughly corresponding to the nighttime mean temperature) with OSA severity. After adjusting for daytime mean temperature in the model, exposure to elevated temperatures during the night can also lead to adverse effects.
In the stratified analysis, the effects of higher temperatures on OSA severity were stronger among men, participants with a body mass index ≥24 kg/m2, those aged 45 years and older, individuals with a history of hypertension and diabetes, and during the cold season. The study results suggest clinicians should consider the impact of high temperatures on OSA severity during clinical evaluation and personalized treatment. It is also necessary that all health protection plans should be enhanced for vulnerable populations, thereby reducing the burden of OSA-related diseases.
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See the article:
Higher ambient temperatures may worsen obstructive sleep apnea: A nationwide smartwatch-based analysis of 6.2 million person-days