Good sleep and regular exercise are essential for mental and physical health. But can exercise help if you are sleep-deprived? A study has found that moderate exercise for 20 minutes after a sleepless night can improve brain power.
Researchers from the University of Portsmouth evaluated how sleep, oxygen levels and exercise affected a person's cognitive ability, the capacity of the mind to perform tasks. The study, published in the journal Physiology and Behaviour, suggests that a bout of moderate-intensity exercise can help improve the cognitive function of people regardless of sleep deprivation and oxygen levels.
"We know from existing research that exercise improves or maintains our cognitive performance, even when oxygen levels are reduced. 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(insufficient oxygen levels)," said Joe Costello, corresponding author of the study.
"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 the brain," Costello added.
The team conducted two experiments, each involving 12 participants. In the initial test, researchers evaluated how partial sleep deprivation affected a person's cognitive performance. During this trial, the participants were allowed to sleep only for five hours every night for three days.
The second test assessed the impact of total sleep deprivation and hypoxia, where participants spent a night without sleep and were put in a hypoxic environment.
Each morning, the participants in both trials were given seven tasks to perform at rest and while cycling. They were also asked to rate their levels of sleepiness and mood before completing the tasks.
The results of both trials showed improvement in cognitive performance after 20 minutes of cycling.
Researchers said they chose moderate activity as more intense exercise might turn into a stressor and bring negative effects.
"Because we were looking at exercise as a positive intervention, we decided to use a moderate intensity program as recommended in existing literature. If the exercise was any longer or harder it may have amplified the negative results and became a stressor itself," Costello said.
"One potential hypothesis for why exercise improves cognitive performance is related to the increase in cerebral blood flow and oxygenation, 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," co-lead author Thomas Williams said.
The researchers also looked into possible reasons for how exercise helps with cognitive performance even when a person is sleep-deprived and has low levels of oxygen. They attribute it to the changes in brain-regulating hormones, cerebral blood flow, arousal and motivation after exercise.
The study also found that a person's cognitive performance is not entirely dependent on the prefrontal cortex (PFC) area of the brain.
"Our findings suggest the mechanisms behind cognitive performance may not be isolated to this area, and instead, we should consider it being the product of a series of coordinated processes widely distributed across different cortical and subcortical regions," explained co-lead author Juan Ignacio Badariotti.
