Short sleep prevents benefits of exercise for the brain

Exercising has numerous benefits for the body like preventing chronic disease, lengthening life, warding off dementia, slowing cognitive decline and much more. But, the amount of sleep received may be just as important — at least when it comes to the benefits of exercise and how well the  brain functions as you age.

According to a new study, researchers discovered people with more frequent, higher-intensity physical activity who slept less than six hours a night, on average, had faster overall cognitive decline than short sleepers who exercised infrequently. “Our study suggests that getting sufficient sleep may be required for us to get the full cognitive benefits of physical activity”, said lead author Dr Mikaela Bloomberg, a research fellow at the Institute of Epidemiology & Health Care at the University College London. “It shows how important it is to consider sleep and physical activity together when thinking about cognitive health,” she said.

Researchers followed nearly 9,000 adults for over 10 years who were part of the English Longitudinal Study of Ageing, a longitudinal study on people older than age 50 funded by the UK Government and the US National Institute on Aging. In addition to an initial workup, participants go through a follow-up interview and cognitive testing every two years. Anyone with a diagnosis of dementia and with test scores that suggested cognitive decline were excluded from the study, which was published Wednesday in The Lancet Healthy Longevity journal.

Building upon evidence from prior research, the new study found people who had higher levels of physical activity and also slept between six and eight hours per night had better cognitive function as they aged. “We were surprised that regular physical activity may not always be sufficient to counter the long-term effects of lack of sleep on cognitive health,” Bloomberg said. Also, physically active short sleepers in their 50s and 60s experienced more rapid cognitive decline compared with better sleepers — but only to a certain age. In people age 70 and older, the benefits of exercise on the brain was maintained, despite short sleep.

“By age 70 years, the cognitive benefit associated with higher physical activity was maintained over the ­10-year follow-up period,” the authors said, without explanation as to why. “Our results suggest the importance of considering physical activity and sleep together, as these factors might combine in complex ways to influence cognitive trajectories from age 50 years onwards,” the authors concluded.

Keep your bedroom cool — between 60 and 67 degrees Fahrenheit is best for good sleep. Don’t watch TV or work in your bedroom so the brain will think of the room as a place only for sleep. One of the most important things to do, experts say, is make a sleep schedule and stick to it. The brain needs to be trained to go to sleep at a certain hour and rise at a dedicated time every day of the week, including weekends.