Research has indicated connections between the risk of dementia and changes in sleep patterns. According to a recent study, women over 80 who are more sleepy are at higher risk of developing dementia. During the 5-year study, women in their 80s who experienced increasing levels of daytime sleepiness were twice as likely to develop dementia as those with stable sleeping patterns.
According to the estimates, over 55 million people are living with dementia globally, and the number is continuously increasing [1].
Several factors can raise an individual’s risk of developing dementia. These include physical inactivity, uncontrolled diabetes, hypertension, hearing loss, and alcohol and tobacco use [2].
Several studies have proposed that irregular sleep patterns may increase dementia risk. However, it is unclear whether too much or too little sleep has a higher influence.
Exploring the Link Between Sleep Duration and Dementia
According to one extensive study, both long and short sleep duration raised the risk of dementia and cognitive impairment [3]. Similarly, another discovered a correlation between a shorter sleep duration in middle age and an increased risk of dementia [4].
Yet another asserts that dementia and neurodegeneration are associated with sleep durations exceeding nine hours per night [5].
Rather than employing objective measures of wakefulness and sleep, all these investigations relied on participant-reported sleep duration.
Recently, researchers at the University of California, San Francisco, used sleep trackers to monitor the sleep patterns of 733 women in their 80s. They discovered that an increased level of daytime sleepiness, particularly excessive napping, is linked to a doubled risk of dementia. The journal Neurology published the study [6].
Study author Yue Leng, PhD, of the University of California, San Francisco, stated that sleep is crucial for cognitive health because it enables the brain to rest and regenerate, improving our capacity for clear thought and memory. However, little is known about the relationship between sleep and cognitive changes over time and how these changes link to the risk of dementia in later life.
He said that their research revealed that sleep issues could be linked to cognitive aging and could be a risk factor or early indicator of dementia in women in their 80s.
Sleep Patterns in Elderly Women
The study enrolled 733 community-dwelling women from the Study of Osteoporotic Fractures (SOF) who were at least 65 years old, could walk independently, and had not received two hip replacements. The participants’ average age was 82.5 years. None of the participants had dementia or cognitive impairment.
Every participant received an actigraph from the researchers, which they wore on their wrists to track their 24-hour sleep-wake activity.
To have their data included in the analysis, participants had to physically visit the clinic, complete a sleep log, and have at least three successive days of actigraph measurements taken during the initial visit and the five-year follow-up.
Researchers used the data to track changes in circadian rest-activity rhythms (RARs, or the magnitude, timing, and regularity of rest-activity patterns), naps, and nighttime sleep throughout 5 years.
Researchers identified the following three primary sleep profiles:
- Stable sleep (SS): SS was characterized by stable or slightly improved sleep and was observed in 321 women (43.8%).
- Declining nocturnal sleep (DNS): About 256 women (34.9%) experienced worsening circadian RARsS=, moderate increases in napping, and declines in the quality and duration of their nighttime sleep.
- Increasing sleepiness (IS): About 156 women (21.3%) saw deteriorating circadian RARs and significant increases in the length and quality of their daytime and nocturnal sleep.
A Higher Dementia Risk is Associated with Increased Sleepiness.
After five years, researchers assessed participants’ cognitive abilities using a variety of neuropsychological tests, medical diagnoses, or admission to residential nursing home care to determine if they had dementia, mild cognitive impairment (MCI), or normal cognition. Anyone who tested negative for each of these factors was considered intellectually normal.
When analyzing their findings, the researchers adjusted for baseline cognitive capacity, age, education, race, body mass index, diabetes, hypertension, heart attack, and antidepressant use.
During the 5-year follow-up, 93 (12.7%) and 164 (22.4%) of the older cohort’s women experienced dementia and MCI, respectively.
Compared to women with stable sleep patterns over five years, those with increased 24-hour sleepiness were about twice as likely to develop dementia. Nevertheless, a higher risk of MCI was not linked to increased sleepiness.
The authors note that their observational study cannot determine the direction of the association between excessive sleep and dementia.
Limitations and Future Prospects
Leng claims that women in their 80s can experience significant changes in their circadian rhythms, sleeping patterns, and napping habits in just five years.
This emphasizes how future research must examine every facet of daily sleep patterns to clearly understand how variations in these patterns over time may be connected to the risk of dementia.
One of the study’s limitations was that it only included white participants. Therefore, the findings cannot be applied to more diverse groups.
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References
- Dementia Statistics. Alzheimer’s Disease International. https://www.alzint.org/about/dementia-facts-figures/dementia-statistics/. Accessed: 28th March, 2025.
- Reducing Risk for Dementia. Alzheimer’s Disease and Dementia. CDC. https://www.cdc.gov/alzheimers-dementia/prevention/. Published Online: 27th August, 2024. Accessed: 28th March, 2025.
- Chen, J.C., Espeland, M.A., Brunner, R.L., Lovato, L.C., Wallace, R.B., Leng, X., Phillips, L.S., Robinson, J.G., Kotchen, J.M., Johnson, K.C. and Manson, J.E., 2016. Sleep duration, cognitive decline, and dementia risk in older women. Alzheimer’s & Dementia, 12(1), pp.21-33.
- Sabia, S., Fayosse, A., Dumurgier, J., van Hees, V.T., Paquet, C., Sommerlad, A., Kivimäki, M., Dugravot, A. and Singh-Manoux, A., 2021. Association of sleep duration in middle and old age with incidence of dementia. Nature communications, 12(1), p.2289.
- Westwood, A.J., Beiser, A., Jain, N., Himali, J.J., DeCarli, C., Auerbach, S.H., Pase, M.P. and Seshadri, S., 2017. Prolonged sleep duration as a marker of early neurodegeneration predicting incident dementia. Neurology, 88(12), pp.1172-1179.
- Milton, S., Cavaillès, C., Ancoli-Israel, S., Stone, K.L., Yaffe, K. and Leng, Y., 2025. Five-year changes in 24-hour sleep-wake activity and dementia risk in oldest old women. Neurology, 104(8), p.e213403.
- Lang, K. Is excessive sleepiness as we age a warning sign of dementia? Medical News Today. https://www.medicalnewstoday.com/articles/is-excessive-sleepiness-as-we-age-a-warning-sign-of-dementia. Published Online: 19th March, 2025. Accessed: 28th March, 2025.
- Sleepier during the day? For some older people, it’s linked to twice the dementia risk. Science Daily. https://www.sciencedaily.com/releases/2025/03/250319172910.htm. Published Online: 19th March, 2025. Accessed: 28th March, 2025.
- Daytime sleepiness may double dementia risk in elderly women. News Medical. https://www.news-medical.net/news/20250320/Daytime-sleepiness-may-double-dementia-risk-in-elderly-women.aspx. Published Online: 20th March, 2025. Accessed: 28th March, 2025.
