Objective sleep tracking reveals that nighttime rest, daytime naps, and changes in circadian rhythms can be early warning signs of declining health in older women.
Study: Multidimensional sleep-wake changes and risk of all-cause and cardiovascular disease mortality in older women. Image credit: amenic181 / Shutterstock
In a recent study published in the journal communication medicineResearchers looked at the association between five-year changes in sleep-wake patterns and risk of cardiovascular disease (CVD) and all-cause mortality in the oldest women in their 80s and 90s.
Circadian rhythms and sleep patterns change significantly with age. These changes include increased sleep fragmentation, decreased circadian rhythms, increased sleep onset latency, and reduced sleep efficiency. They are well documented from midlife through the 60s and 70s of life, but are less defined thereafter.
Studies have identified that older adults with poor sleep quality, long or short sleep duration, long daytime naps, and weak rest-activity rhythm (RAR) are at increased risk of death from all causes or cardiovascular disease. Nevertheless, little is known about how long-term changes in sleep-wake patterns relate to mortality risk in older populations.
About research
In this study, researchers evaluated the association between changes in circadian RAR and 24-hour sleep patterns over 5 years and risk of CVD and all-cause mortality. They included participants in the Osteoporotic Fracture Study, which recruited community-dwelling white women aged 65 and older from 1986 to 1988.
Specifically, participants who had actigraphy data at the first two sleep visits from 2002 to 2004 and 2006 to 2008, respectively, and were subsequently followed up for mortality were included. At both visits, participants wore the actigraph on their wrist for at least 3 consecutive days. In this study, we investigated nine sleep-wake indicators across the domains of circadian RAR, nocturnal sleep, and naps.
Nighttime sleep parameters included sleep efficiency, wake after sleep onset (WASO), and total sleep time (TST). Circadian RAR parameters were amplitude, robustness, apex, and mesol, which is a measure of mean activity level. Nap parameters were nap duration and frequency. The primary outcomes were CVD mortality and all-cause mortality. Participants’ vital status was taken every four to six months, and cause of death was confirmed using death certificates.
Questionnaires were used to collect data on age, education, functional disability, physical activity, self-rated health status, medical conditions, and self-reported sleep apnea. In addition, the modified Mini-Mental State Examination (3MS) and the Geriatric Depression Scale were also administered. The researchers used principal components hierarchical clustering (HCPC) analysis to examine the profile of sleep-wake changes and Cox proportional hazards models to assess associations with outcomes.
Survey results
Overall, 704 Caucasian women with a mean age of 82.5 years at the first sleep visit (2002-2004) were included. Over time, several changes appeared in circadian RAR and sleep patterns. On average, participants had small changes in sleep efficiency, WASO, and TST, but significantly increased nap duration and frequency. Meanwhile, the amplitude, robustness, and mesol decreased significantly, reflecting the worsening of RAR.
Three profiles of long-term changes in circadian RAR, nocturnal sleep, and nap parameters were identified: stable sleep (SS), increasing sleepiness (IS), and decreasing nocturnal sleep (DNS). Approximately 44% of participants showed minimal change or improvement across SS profiles, i.e., parameters. An additional 35.7% of participants had a DNS profile that experienced decreased circadian RAR domains, worsened sleep duration and sleep quality, and a slight increase in napping.
Approximately 20.7% of participants exhibited an IS profile characterized by significantly increased nighttime sleep duration and sleep efficiency, increased daytime nap duration and frequency, and decreased circadian RAR parameters. IS participants were slightly older and had poorer 3MS performance compared to participants with DNS or SS profiles. During a median follow-up of 2.1 years after the second sleep visit, 90 deaths were recorded, including 35 CVD deaths.
Participants with IS or DNS profiles had approximately twice the risk of all-cause mortality as the SS group. In age-adjusted analyses, neither profile was significantly associated with CVD mortality. However, after fully adjusting, DNS was associated with CVD mortality (HR 2.60, 95% CI: 1.03-6.57), but IS was not. Additionally, participants who experienced a significant decrease in amplitude or robustness and a significant increase in nap time had a higher risk of all-cause mortality than participants in the improved or stable groups after adjusting for age. However, the association between amplitude and robustness was attenuated and no longer statistically significant after full adjustment.
In fully adjusted analyses, subjects with increased napping frequency or decreased TST had more than double the risk of CVD mortality. After adjustment for multiple tests, increased DNS profile and nap time remained significantly associated with all-cause mortality. In stratified analyses, a large increase in TST was associated with a 3-fold increase in all-cause mortality risk only among those with a longer baseline TST. Larger reductions were associated with significantly increased risks of all-cause and CVD mortality in those with longer baseline TST, although corresponding interaction tests were not significant. Therefore, this study did not demonstrate that these associations differed between participants with long and short baseline sleep.
conclusion
In summary, the oldest-old women with increased 24-hour sleepiness and decreased nighttime sleep had about twice the risk of all-cause mortality compared with women with stable sleep patterns. Significant increases in nap time were associated with more than twice the risk of CVD and all-cause mortality. However, observational studies cannot prove causation, and changes in sleep patterns may reflect underlying disease rather than contributing directly to mortality. The short follow-up period, low number of deaths from cardiovascular disease, reliance on self-report of sleep apnea, and inclusion of only community-dwelling Caucasian women also limit interpretation and generalizability. These results suggest that long-term changes in circadian rhythms and 24-h sleep in older adults do not simply reflect normal aging, but may serve as markers of increased mortality risk.
Reference magazines:
- Leng Y, Milton S, Yaffe K, et al. (2026). Multidimensional sleep-wake changes and risk of all-cause and cardiovascular disease mortality in elderly women. Communication medicine. Doi: 10.1038/s43856-026-01789-y. https://www.nature.com/articles/s43856-026-01789-y
