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What’s the link between sleep and brain health? The latest research provides new insights. Maria Korneeva/Getty Images
  • Increasing evidence suggests a link between sleep and brain health.Experts say addressing sleep problems early in life is important to preserving our cognitive functions.
  • A new study found that sleep quality issues in early middle-age are associated with accelerated brain aging and cognitive problems later in life.
  • Another study suggests that people who experience disrupted sleep in their 30s and 40s are more likely to have memory and cognitive problems later in life.

Are you getting enough sleep? How good is your sleep quality? Increasing evidence from scientific research has linked “poor sleep” to accelerated brain aging and suggests that addressing sleep problems early in life may help preserve our cognitive functions.

Previous research found that proper sleep can help maintain and improve the brain’s glymphatic system and its ability to clear waste. Researchers also found that sleep disorders and disruptions, such as waking up and returning to sleep at night, may contribute to memory and cognitive problems, which could lead to a higher risk of developing dementia.

In this article, we highlight key findings from two recent studies published in 2024 that offer insights into the link between sleep and brain health and how to better protect our cognitive functions.

In a nutshell:

According to a new study published in Neurology, the medical journal of the American Academy of Neurology, people who experience issues with sleep quality in their early middle age, such as having trouble falling or staying asleep, show more signs of cognitive health problems in late middle age.

While the study shows a correlation between sleep quality and signs of brain aging, the findings do not prove that sleep issues accelerate brain aging.

Key takeaways:

  • The study included 589 people, with an average age of 40 at the start. Participants completed sleep questionnaires at the beginning of the study and then again five years later. Researchers divided the participants into three groups based on the number of self-reported “poor sleep” characteristics: low (0-1), middle (2-3), and high (more than 3).
  • The participants also had brain scans 15 years after the study began. Researchers analyzed the scans, where the level of brain shrinkage corresponds to a specific age, and used machine learning to determine each participant’s brain age.
  • The study found that several sleep characteristics, including sleep quality, early morning awakening, and difficulty falling asleep or staying asleep, were linked to accelerated brain aging, especially when people consistently had these sleep problems over five years. In addition, researchers found that people in the middle group had an average brain age that was 1.6 years older than those in the low group, and those in the high group had an average brain age of 2.6 years older.
  • “Our findings highlight the importance of addressing sleep problems earlier in life to preserve brain health, including maintaining a consistent sleep schedule, exercising, avoiding caffeine and alcohol before going to bed and using relaxation techniques,” said study author Kristine Yaffe, MD, Professor of Psychiatry, Neurology and Epidemiology at the University of California San Francisco. “Future research should focus on finding new ways to improve sleep quality and investigating the long-term impact of sleep on brain health in younger people.”
  • Study limitation: The participants reported their own sleep problems, and it is possible they did not report them accurately.

In a nutshell:

According to a previous study published in January in Neurology, people who experience disrupted sleep in their 30s and 40s are more likely to have memory and cognitive problems later in life.

“Even in early adulthood, sleep quality results in measurable changes in cognitive performance by mid-life. The study findings support the importance of sleep quality, uninterrupted, or unfragmented sleep in relation to cognitive performance,” said David Merrill, MD, PhD, a geriatric psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in California who was not involved in the study.

Key takeaways:

  • Researchers examined the sleep patterns and durations of 526 people, with an average age of 40 at baseline, who were followed for 11 years. Participants wore a wrist monitor for three consecutive days, one year apart. They also reported bedtimes and wake times in a sleep diary, completed a sleep quality survey, and received a sleep quality “score” ranging from 0 to 21, with higher scores indicating more sleep quality issues. In addition, the participants completed a series of memory and thinking tests.
  • After adjusting for age, gender, race, and education, researchers reported that the people with the most disruptive sleep were more than twice as likely to have cognitive performance issues later in life as those with the least disruptive sleep. They also found that sleep duration and self-reported sleep quality were not associated with cognition in middle age.
  • “We all know that sleep is good for you and the results of this study are undoubtedly true,” said Steven Feinsilver, MD, the director of the Center for Sleep Medicine at Northwell Lenox Hill Hospital in New York who was not involved in the study. “But the question is, what came first: Did poor sleep quality cause cognitive dysfunction or did cognitive dysfunction cause poor sleep quality?”

“Things like lowering stress levels as we head towards bedtime, taking a warm shower or bath, sleeping in a colder room at a lower temperature — all these have been tied to possibly improving the quality of sleep during the night. We also know about things like avoiding screen time later in the afternoon and into the evening (and) filtering out blue light,” Merrill told Medical News Today.

“It is important to prioritize sleep health,” said Scott Kaiser, MD, a geriatrician and the director of geriatric health for the Pacific Neuroscience Institute in Santa Monica, California. “Sleep hygiene – preparing your environment, going to and getting up at the same time – is all very important.”

“It is amazing how many of us have poor sleep hygiene. Although there are certainly other lifestyle factors that contribute to dementia, sleep is one we can focus on by being consistent,” Kaiser said.