Getting less than 6 hours of sleep daily reduces cognitive benefits of exercise, says study

New research has found that lack of enough sleep reduces the benefits derived from daily exercise in the protection against cognitive decline.

According to the study conducted by researchers from the University College London (UCL) in the UK and published in The Lancet Healthy Longevity medical journal, getting less than six hours of daily sleep will reduce the protective capability of regular physical activity against cognitive decline.

The study looked at cognitive function over 10 years in 8,958 people aged between 50 and 95 in England. The research team analysed how different combinations of sleep and physical exercise habits impacted people’s cognitive abilities at various ages.

Minimum six hours of sleep needed to protect cognitive abilities

The study found that people who were physically active but slept for shorter periods – less than six hours daily on average – suffered quicker cognitive overall, implying that their cognitive level was equal to those who conducted less physical exercise over the ten-year period.

Dr Mikaela Bloomberg, postdoctoral research fellow in cognitive ageing epidemiology at the UCL Institute of Epidemiology & Health Care, is the lead author of the study. She said, “Our study suggests that getting sufficient sleep may be required for us to get the full cognitive benefits of physical activity. It shows how important it is to consider sleep and physical activity together when thinking about cognitive health.

“Previous studies examining how sleep and physical activity might combine to affect cognitive function have primarily been cross-sectional – only focusing on a snapshot in time – and 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.”

The study found that those who slept between six and eight hours daily and had higher levels of regular physical exercise had better cognitive functions over time.