Not enough sleep may cancel the benefits of exercise on brain health

Physical activity at any age has a broad range of health benefits. However, if you’re not getting enough sleep in middle age, exercise may not be providing enough to offset cognitive decline.

A new study out of University College London (UCL) has found that active adults aged in their 50s and 60s, who get less than six hours of sleep a night, showed as much cognitive impairment in the areas of learning, attention and memory as those who had a more sedentary lifestyle.

The researchers looked at data from the English Longitudinal Study of Ageing, featuring nearly 9,000 people aged 50 and over. Their cognitive abilities were assessed through memory and verbal fluency tests that spanned 10 years.

“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 from the UCL Institute of Epidemiology & Health Care. “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.”

UCL has previously looked into the effects of a lack of sleep and cognitive decline, and quality and quantity of slumber has also been linked to higher risk of dementia. But little is known about how a lack of sleep can undermine exercise when it comes to brain health.

At the beginning of the study, physical activity was linked to better cognitive function regardless of the number of hours of shuteye. As time progressed, however, the shorter sleepers who were still very active performed worse in cognition tests.

It’s not all bad news, however. The decade-long study showed the biggest impact of poor sleep affecting those in their 50s and 60s. Beyond 70, the benefits of exercise were clear, helping maintain brain health despite this cohort reporting less sleep.

“It is important to identify the factors that can protect cognitive function in middle and later life as they can serve to prolong our cognitively healthy years and, for some people, delay a dementia diagnosis,” said co-author Andrew Steptoe, a professor at UCL Institute of Epidemiology & Health Care.

The World Health Organization already identifies physical activity as a way to maintain cognitive function, but interventions should also consider sleep habits to maximize long-term benefits for cognitive health.”

The study was published in the journal The Lancet Healthy Longevity.

Source: University College London

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