Chronic sleep deprivation, a risk factor for cardiovascular and Alzheimer’s diseases, is common among adults in industrialized nations, with many reporting less than seven hours of sleep each night during the workweek. Acute sleep deprivation impairs cognitive function, working memory, attention, and executive function, increasing the rate of mistakes made while driving, at work, and at home. A recent report details the effects of aerobic exercise on cognitive function following a night of sleep deprivation.
Sleep deprivation has been shown to decrease brain oxygen saturation, contributing to cognitive impairment. However, previous research has demonstrated that aerobic exercise increases blood flow to the prefrontal cortex, activating key brain regions that improve cognitive function. Enhanced blood flow to the brain during exercise increases oxygen saturation in brain tissue and improves energy metabolism.
In this study, the researchers recruited 12 participants (average age, 21 years) and measured their baseline maximum aerobic capacity while riding a stationary bicycle. On a separate study visit, participants completed cognitive testing and answered questionnaires before and after cycling for 20 minutes at 60 percent of their maximum aerobic capacity. Participants wore an electrode cap on their heads during exercise to measure electrical activity in the brain. They completed this study visit twice in random order, once after a full night of rest and once following a night of total sleep deprivation.
Sleep-deprived participants reported feeling sleepier and performed significantly worse on cognitive tests prior to exercise. Following exercise, both sleepiness and cognitive function were improved in both groups, although cognitive scores were still comparatively worse in the sleep-deprived group. Under both rested and sleep-deprived conditions, blood flow to the prefrontal cortex increased within 12 minutes of initiating exercise and was maintained until the end of exercise. However, the researchers did not find a relationship between oxygenation levels and cognitive function, so whether exercise-induced brain oxygenation had a beneficial effect on cognitive function is unclear.
The authors concluded that exercise corrects the cognitive impairment induced by sleep deprivation, although future research is needed to identify the best exercise protocol to maximize the benefits on brain oxygenation following sleep deprivation.
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