A new University of Arizona study of more than 23,000 adults suggests that several common sleep patterns may be linked to signs of brain aging years later.
The study analyzed existing brain scans and questionnaire data from more than 23,000 middle-aged and older adults in a large biomedical database. The research is part of a wider collaboration involving the U of A Department of Psychology, the Zuckerman College of Public Health, and the University of Southern California.
The researchers found that three sleep behaviors were clearly linked to a marker of brain aging in otherwise healthy people: sleeping outside the recommended range of seven to nine hours, frequent daytime napping, and sleeplessness. Each was associated with a larger volume of white matter lesions, areas of change in the brain that can accumulate with age.
Madeline Ally, the study's lead author and a graduate researcher at the Department of Psychology, said sleep is often examined as a single overall measure instead of as a set of separate behaviors and patterns. That approach can make it harder to see how specific aspects of sleep relate to brain aging.
"Sleep is a universal but complex behavior, and there is still much to learn about how different aspects of sleep relate to brain health," Ally said.
Sleep habits leave brain clues
Participants first answered a questionnaire from 2006 to 2010 about five sleep behaviors: how long they slept, whether they napped during the day, whether they experienced sleeplessness, whether they unintentionally dozed during the day, and whether they snored. About nine years later, participants received brain MRI scans, which researchers used to measure white matter lesion volume.
At first, all five sleep behaviors were linked to greater lesion volume. After the researchers adjusted for blood vessel health and lifestyle factors that can also shape brain health, such as high blood pressure, smoking, and inactivity, three behaviors remained significant: sleeping outside the recommended range, frequent daytime napping, and sleeplessness. Snoring and unintentional daytime dozing no longer stood out.
Three key behaviors affecting the brain
In a follow-up analysis, the researchers examined sleep duration more closely. They found that participants who slept fewer than seven hours a night had higher lesion volume than those who slept within the recommended range.
Alongside short sleep duration, the study highlighted greater sleeplessness as another independent factor linked to increased brain lesions.
The results regarding daytime napping were also notable. While some evidence suggests that brief, occasional naps can support daytime alertness, this study indicates that frequent daytime napping may have a contrasting effect, contributing to structural signs of brain aging.
Researchers emphasized one encouraging takeaway from these findings: these three sleep behaviors are potentially modifiable. Improving overall sleep quality — by addressing sleeplessness, optimizing nighttime sleep duration, and managing daytime napping — could offer a practical way to reduce the impacts of brain aging and potentially lower the risk for cognitive decline.