February 21, 2024
People in their 30s and 40s who tend to have disrupted sleep, waking up numerous times during the night, are at higher risk of developing memory and thinking problems later in life, according to a new report. The study found that for middle-aged men and women, the soundness of your sleep, rather than how many hours you typically spend sleeping each night, may be most important for maintaining brain health. Keeping the brain healthy in midlife may, in turn, help to decrease the risk of developing Alzheimer’s disease later in life.
The findings add to growing evidence linking poor sleep with an increased risk for cognitive problems. Most of those earlier studies were conducted in older people, in their 60s or 70s, an age when memory loss and other symptoms of Alzheimer’s disease are more likely to appear.
“Given that signs of Alzheimer’s disease start to accumulate in the brain several decades before symptoms begin, understanding the connection between sleep and cognition earlier in life is critical for understanding the role of sleep problems as a risk factor for the disease,” said study author Yue Leng of the University of California, San Francisco. “Our findings indicate that the quality rather than the quantity of sleep matters most for cognitive health in middle age.”
This latest study looked at 526 people in their mid-30s to late 40s. Their average age was 40. Researchers followed them for an average of 11 years, at which time they underwent tests of memory and thinking skills.
At the start of the study, participants wore an activity monitor on their wrists to assess their typical sleep habits. They slept, on average, for about six hours a night. But some had much more disrupted sleep than others, waking up for short periods numerous times during the night, even if they were not aware of it.
Using a measure known as sleep fragmentation, the researchers divided participants into three groups according to how soundly they slept. They found that those with the most fragmented sleep were up to three times as likely to have the most thinking and memory problems 10 years later than their peers who slept most soundly. Of the 175 participants with the most disrupted sleep, 44 scored poorly on tests of cognitive performance 10 years later. Among the 176 with the least disrupted sleep, only 10 scored poorly on the memory tests.
Sleep duration did not show a similar correlation with declines in cognitive skills. The findings appeared in the journal Neurology, the medical journal of the American Academy of Neurology.
“More research is needed to assess the link between sleep disturbances and cognition at different stages of life and to identify if critical life periods exist when sleep is more strongly associated with cognition,” Dr. Leng said. “Future studies could open up new opportunities for the prevention of Alzheimer’s disease later in life.” Previous research has found that up to 40 percent of Alzheimer’s cases could be prevented through measures including better sleep, maintaining good hearing and vision, and keeping heart health in check.
Sleep quality tends to diminish with advancing age, and life circumstances like raising young children, job stress and menopause can also impact sleep. Regardless of the underlying causes of poor sleep, these latest findings underscore the importance of sound sleep throughout life for brain health.
While many people turn to sleeping pills to sleep better, these drugs do not fully induce deep sleep and may in fact increase the risk of developing Alzheimer’s disease. There are safer alternatives to medications to promote a sound night’s sleep that only require a change in routine.
The Sleep Foundation stresses the importance of daily habits to help promote sounder sleep. Suggested measures include going to bed and waking up at the same time, even on weekends; minimizing the use screens and electronic devices, which can emit blue light that disrupts levels of the sleep hormone melatonin, near bedtime; avoiding alcohol or caffeine late in the day; taking time to relax and unwind before going to bed; and getting some sunshine and exercise during the day. Psychological approaches like cognitive behavioral therapy, or CBT, which teaches people to challenge negative or stressful thoughts at bedtime, can also help.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Yue Leng, PhD; Kristen Knutson, PhD; Mercedes R. Carnethon, PhD and Kristine Yaffe, MD: “Association Between Sleep Quantity and Quality in Early Adulthood With Cognitive Function in Midlife.” Neurology, January 3, 2024
