How Short Sleep, Frequent Naps and Insomnia May Speed Up Brain Aging

Common sleep habits associated with brain aging, new research shows

A large analysis of brain scans and sleep questionnaires has revealed that several everyday sleep patterns may correspond with early signs of brain aging.

The investigation, published in Alzheimer’s & Dementia, drew on data from more than 23,000 adults ranging from middle age to senior years, sourced from a national biomedical repository.

Researchers from the University of Arizona’s psychology department, the Zuckerman College of Public Health, and the University of Southern California collaborated on the study.

Three specific sleep behaviors emerged as independent predictors of increased white‑matter lesion volume—a marker of brain damage that accumulates with age and raises the likelihood of dementia, including Alzheimer’s disease. These behaviors are sleeping less or more than the recommended seven‑to‑nine hours, taking frequent daytime naps, and experiencing frequent sleeplessness.

Lead author Madeline Ally, a graduate researcher in psychology, noted that most sleep research treats sleep as a single variable, which can mask how distinct habits influence brain health.

“Sleep is a universal yet complex behavior, and there is still much to learn about how different aspects of sleep relate to brain health,” she explained.

Participants initially answered a baseline survey between 2006 and 2010, reporting on five sleep dimensions: total sleep time, daytime napping, insomnia, unintentional daytime dozing, and snoring. Approximately nine years later, they underwent magnetic‑resonance imaging, allowing investigators to quantify white‑matter lesion volumes.

While all five sleep factors showed a raw association with larger lesion volumes, adjustments for vascular health and lifestyle variables—such as hypertension, smoking, and physical inactivity—left only three habits statistically significant: deviation from the optimal sleep duration, regular daytime napping, and higher levels of sleeplessness. Snoring and unintentional dozing lost their predictive power after these controls.

The nap findings are noteworthy because prior work suggests short naps can boost alertness and cognition. Senior author Gene Alexander, a psychology professor, cautioned that the questionnaire did not capture nap length or timing, and future studies should differentiate brief, occasional naps from longer, frequent ones.

A secondary analysis focused on sleep duration, revealing that participants who averaged fewer than seven hours per night exhibited greater lesion volumes than those who slept within the recommended range.

“Our findings suggest that insufficient sleep may lead to higher white‑matter lesion volumes as we age,” Alexander said. “We did not observe a similar increase among long sleepers, but this should be examined in cohorts with more extended sleepers.”

Importantly, the three identified behaviors are modifiable. Alexander emphasized that improving sleep quality could potentially mitigate brain‑aging effects and lower the risk of neurodegenerative conditions such as Alzheimer’s disease.