Sleep habits affect brain aging

The researchers analyzed five aspects of sleep: duration of nighttime rest, daytime naps, problems with falling asleep, involuntary daytime naps, and snoring. The participants completed a baseline questionnaire between 2006 and 2010, and approximately nine years later, they underwent an MRI scan of their brains to measure the extent of white matter lesions. These lesions accumulate with age and are associated with an increased risk of dementia, including Alzheimer’s disease.

Initially, all five behavioral patterns were found to be associated with an increase in lesion volume. However, after the researchers took into account other factors such as vascular health, blood pressure, smoking, and physical activity, only three habits remained significantly associated with snoring. These were sleeping outside the recommended range of 7-9 hours, frequent daytime naps, and difficulty falling asleep. When these factors were taken into account, the association between snoring and daytime naps was no longer as clear.

According to Madeline Ellie, the study’s lead author and a graduate student in psychology, sleep is often viewed as a single indicator rather than a combination of individual patterns and habits. This approach may overlook important details about how sleep affects brain aging. “Sleep is a universal yet complex behavior, and we have much to learn about how different aspects of sleep are linked to brain health,” she notes.

An additional analysis of sleep duration revealed: Those who slept less than seven hours per night had more white matter lesions than those who followed the recommended sleep duration. However, the study did not find a clear negative effect of longer sleep, although the senior author, Professor Gene Alexander of the Department of Psychology, said that more research with a larger number of participants who slept for extended periods was needed to draw definitive conclusions.

The results regarding daytime sleep are particularly interesting. It is known that short daytime naps can positively impact alertness and cognitive function. However, the questionnaire did not record the duration or time of day when people slept during the day. As Alexander explains, further research is needed to determine whether the effects of short, occasional daytime naps differ from those of longer and more frequent naps.

Jin Alexander emphasizes an important aspect of the identified factors: all three habits can be modified. “Sleep is a potentially modifiable risk factor. If we can improve sleep quality, it could help reduce the effects of brain aging and potentially reduce the risk of developing dementias such as Alzheimer’s disease,” he says.