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It’s well-known that regular physical activity can protect older adults from memory and cognitive decline. But recent research shows that this protective effect may be weakened in people who sleep less than six hours a night.
How Was the Study Conducted?
A team of British scientists tracked cognitive function in 8,958 people aged 50 and older over 10 years. The assessment relied on memory tests: participants were asked to recall a list of 10 words immediately and again after a delay. They also did a free-recall task, naming as many animals as they could in one minute.
The researchers examined how combinations of sleep habits and physical activity affected memory and cognition over time. They found that physically active people who averaged less than six hours of sleep per night experienced a faster overall decline in cognitive function. After 10 years, their memory and thinking skills were similar to those of less active peers who slept longer.
Exercise and Good Sleep Go Hand in Hand
Lead author Mikaela Blumberg told the Daily Mail the team’s findings suggest adequate sleep plays a key role in getting cognitive benefits from physical activity. So, maintaining cognitive health should include getting at least six hours of quality sleep alongside regular exercise.
At the study’s start, more physically active people showed better cognitive function regardless of sleep duration. But over the 10-year follow-up, people who slept less than six hours declined faster than those who slept six to eight hours a night.
The rapid decline was particularly evident in people aged 50 to 60. However, participants aged 70 and above seemed to retain the cognitive benefits of exercise despite shorter sleep durations.
Co-author Professor Andrew Steptoe emphasizes the importance of identifying factors that can help preserve cognitive function in middle and older age. That could help people live longer, healthier lives and, for some, delay the onset of dementia.
The WHO already recognizes physical activity as a way to support cognitive function. The findings suggest sleep habits must also be considered to maximize long-term health benefits.
