Impacts of Sleep on Brain Health in Aging

How we sleep could have significant effects on our brain health as we grow older. A recent study from the University of Arizona suggests that certain common sleep behaviors are linked to signs of brain aging.

This research, published in the journal Alzheimer’s & Dementia, analyzed existing brain scans and responses from over 23,000 middle-aged and older individuals sourced from a large biomedical database. It’s part of a larger collaborative effort between the University of Arizona’s Department of Psychology, the Zuckerman College of Public Health, and the University of Southern California.

The researchers pinpointed three sleep behaviors that appeared to correlate with a marker of brain aging: sleeping less than the recommended seven to nine hours, frequent daytime napping, and sleeplessness. Each of these was associated with an increase in white matter lesions, which are areas in the brain that can become damaged with age and are linked to a higher risk of dementia, including Alzheimer’s disease.

Madeline Ally, the study’s lead author and a graduate researcher, remarked that sleep is often approached as a singular measurement rather than examining distinct patterns and habits. This can obscure the relationship between sleep and brain aging.

“Sleep is universal yet complex, and we still have much to uncover about how its various aspects relate to brain health,” she noted.

Participants in the study filled out a questionnaire from 2006 to 2010 that covered five sleep behaviors: duration, daytime napping, sleeplessness, unintentional daytime dozing, and snoring. Roughly nine years later, they underwent brain MRI scans, and the researchers measured the volumes of white matter lesions. This study was carried out in partnership with David Raichlen, a key collaborator and professor of human and evolutionary biology at USC.

Initially, all five behaviors were linked to greater lesion volume. Still, when the researchers accounted for factors like blood vessel health and lifestyle habits—such as high blood pressure, smoking, and physical inactivity—three behaviors remained particularly significant: not getting enough sleep, frequent napping, and significant sleeplessness. Snoring and unintentional daytime dozing were excluded from this notable list.

The insights on daytime napping stood out, especially since prior research indicates that short naps can boost alertness and cognitive function. Gene Alexander, the study’s senior author and psychology professor, explained that the questionnaire didn’t capture details about the duration or timing of individual naps. This prompts the need for future studies to investigate whether short, occasional naps affect the brain differently than longer, more frequent ones.

A follow-up analysis focused on sleep duration revealed that participants who slept less than seven hours nightly had increased lesion volume compared to those adhering to the recommended range. “Our findings imply that insufficient sleep may lead to larger white matter lesion volumes as we age,” Alexander stated. “We didn’t observe heightened effects in individuals who reported longer sleep durations, but this area certainly warrants more exploration.”

Nonetheless, Alexander highlighted that the three behaviors have a common aspect that is vital for further investigation: they can be modified. “Sleep is one of those potentially changeable risk factors. If we can enhance our sleep quality, it may help mitigate the effects of brain aging and potentially lower the risk of dementias like Alzheimer’s,” he said.