Debating about getting up early for a workout? The results of a new study might be enough to keep you in bed.
A study published in The Lancet Healthy Longevity indicates a lack of sleep negates the cognitive benefits of exercise.
The study involving nearly 9,000 people over the age of 50 showed those who sleep less than six hours a day but are physically active had roughly the same cognitive decline as those who have a normal amount of sleep but aren't physically active.
The research indicated that these adults needed at least six hours of nightly sleep to experience the cognitive benefit of exercise.
"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," said Mikaela Bloomberg, the study's lead author and a professor at University College London.
Bloomberg suggested some of the study's results came as a surprise.
"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," she said.
Researchers assessed cognitive function using an episodic memory test. The test asked participants to recall a 10-word list immediately and then after a delay. The test also involved a verbal fluency test, asking participants questions like how many animals they could name in a minute.
The World Health Organization recommends that most adults get at least 150 to 300 minutes a week of moderate-intensity exercise or 75 to 150 minutes weekly of vigorous exercise.
The Centers for Disease Control and Prevention recommends that adults get at least seven hours of nightly sleep.
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