There’s nothing quite like a bad night’s sleep to make you feel utterly rubbish. But according to a new study, there may be a way to reverse some of the negative effects of a bad night’s sleep – and it only takes 20 minutes.

The study, which was led by the University of Portsmouth, set out to explore how our sleep, oxygen levels and exercise can affect our ability to perform mental tasks. We know that a bad night’s sleep can make it harder for us to concentrate and can affect our emotions, but the team wanted to explore whether there was a way to reverse this.

To find out, they devised two separate experiments, recruiting a group of 12 people to take part in each one. Both experiments looked at the cognitive performance of the participants both before and after exercise, but the sleep disruption they experienced beforehand varied; the first group only experienced partial sleep disruption, while the second group experienced total sleep deprivation and hypoxia (low blood oxygen levels).  

The partial sleep disruption group were only allowed five hours of sleep a night over the course of three days. When they woke, they were given seven tasks to perform to measure their cognitive performance at rest, and then again while cycling for 20 minutes. They were also asked to rate their sleepiness and mood.

The other group went one full night without sleep and were then put in a hypoxic environment (a space with low oxygen), where they were asked to complete the same tasks at rest and while cycling for the same 20 minutes.

The researchers found that the moderate-intensity exercise improved cognitive performance regardless of the level of sleep deprivation the people were experiencing. Those who were in the low oxygen environment also reaped the benefits – a result the researchers say could also help people who travel to high altitudes.

So, what does that mean for us? Well, while you might not feel at your best after a bad night’s sleep, the study shows that exercise can make a difference to how you think and feel – although only in small bouts.  

The study’s authors actually made the decision to limit the intensity and duration of the exercise to ensure the movement was beneficial – as pre-existing research suggests that exercising for any longer or harder can actually stress out the body and amplify the negative effects of poor sleep.

That means you don’t want to go for a super-long run or spend 20 minutes killing yourself on an exercise bike. Instead, do something that’s rigorous enough to raise your heart rate a little, but not enough that you’re out of breath or overly sweaty – something like a brisk walk or gentle cycle will do.  

Commenting on the study, one of the authors, Dr Joe Costello, said the results sent a powerful message. “We know from existing research that exercise improves or maintains our cognitive performance, even when oxygen levels are reduced,” he explained. 

“But this is the first study to suggest it also improves cognitive performance after both full and partial sleep deprivation, and when combined with hypoxia.”

He continued: “The findings significantly add to what we know about the relationship between exercise and these stressors and help to reinforce the message that movement is medicine for the body and brain.” 

Images: Getty