This much exercise helps your brain function after a bad night’s sleep

Feeling groggy after a night of tossing and turning?

You’ve got plenty of company: Over 20% of American adults say they “rarely or never” wake up feeling well-rested, according to a recent survey from US News & World Report.

And almost half (43%) of survey respondents said they have experienced insomnia in 2023. If you’re among them — we’re looking at you, New Yorkers — there’s a quick way to get through your day without nodding off in front of the boss.

Just 20 minutes of moderate exercise, like riding a bike or a brisk walk, improves cognitive performance, regardless of a person’s sleep status, according to a new study.

“We know from existing research that exercise improves or maintains our cognitive performance, even when oxygen levels are reduced,” study co-author Dr. Joe Costello of the UK’s University of Portsmouth said in a news release.

“But this is the first study to suggest it also improves CP [cognitive performance] after both full and partial sleep deprivation,” Costello added.

The study, published in the journal Physiology and Behaviour, involved two experiments, each with 12 different participants. The first looked at the impact of partial sleep deprivation on a person’s cognitive performance, and the second examined the impact of total sleep deprivation and hypoxia (low oxygen levels).

In the first experiment, participants were only allowed five hours of sleep a night over the course of three days. Each morning they were given seven mental tasks to perform at rest, and then while cycling on a stationary recumbent bicycle.

In the second experiment, participants went a whole night without sleep, and were then put in a low-oxygen environment at the university’s Extreme Environment labs. Despite oxygen levels being decreased, exercise still improved cognitive performance.

In both experiments, all participants experienced a significant improvement in cognitive performance after spending 20 minutes cycling.

The research revealed that the effects of three nights of partial sleep on cognitive functions were inconsistent among the participants, possibly because some people are more resilient to a moderate sleep deficit.

However, regardless of sleep status, moderate-intensity exercise improved performance across all the cognitive tasks. 

“One potential hypothesis for why exercise improves cognitive performance is related to the increase in cerebral blood flow and oxygenation,” said co-lead author Dr. Thomas Williams of the university’s Extreme Environment Research Group.

“However, our findings suggest that even when exercise is performed in an environment with low levels of oxygen, participants were still able to perform cognitive tasks better than when at rest in the same conditions,” Williams said.

For people who regularly struggle with sleep, other experts offer this advice: Quit worrying about it.

Dr. Reena Mehra, a director of sleep-disorders research at the Cleveland Clinic, said that consciously focusing on falling asleep may impede the process. “It works against the individual,” she told The Wall Street Journal.