Summary: New research reveals that moderate exercise improves cognitive performance (CP) even under conditions of sleep deprivation and low oxygen levels.
The study involved two experiments with 24 participants in total, examining the effects of partial and total sleep deprivation, as well as hypoxia, on CP. Results consistently showed that a 20-minute cycling session significantly enhanced CP regardless of sleep status or oxygen levels.
This groundbreaking study adds to the understanding of how physical activity can mitigate the cognitive deficits caused by common stressors.
Key Facts:
- The study demonstrates that moderate intensity exercise improves cognitive performance even after full or partial sleep deprivation and in hypoxic conditions.
- In the first experiment, participants, limited to five hours of sleep per night, showed inconsistent CP at rest but improved performance post-exercise.
- The second experiment revealed that despite an entire night without sleep and reduced oxygen levels, participants’ CP improved after exercising.
Source: University of Portsmouth
New research has explored how sleep, oxygen levels, and exercise affects our ability to perform mental tasks.
Sleep is fundamental in maintaining a healthy lifestyle, with adults recommended between seven and nine hours a night. However, recent reviews indicate that 40 per cent of the global population don’t get enough.
Consequences of chronic sleep deprivation include cardiovascular disease, obesity, neurodegenerative disorders, and depression. In the short term, a lack of sleep can reduce cognitive performance (CP), which takes a toll on your attention span, judgement, and emotional state.
A study, led by the University of Portsmouth, has found cognitive performance improves during a bout of moderate intensity exercise, regardless of a person’s sleep status or oxygen levels.
Dr Joe Costello, from the University’s School of Sport, Health & Exercise Science (SHES), said: “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 CP after both full and partial sleep deprivation, and when combined with hypoxia.
“The findings significantly adds to what we know about the relationship between exercise and these stressors, and helps to reinforce the message that movement is medicine for the body and the brain.”
The study, published in Physiology and Behaviour, involved two experiments, each with 12 participants (24 in total). 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. In both, all participants experienced an improvement in cognitive performance after a bout of 20 minutes of cycling.
“Because we were looking at exercise as a positive intervention, we decided to use a moderate intensity programme as recommended in existing literature”, added Dr Costello.
“If the exercise was any longer or harder it may have amplified the negative results and became a stressor itself.”
In the first experiment, individuals were only allowed five hours of sleep a night, over three days. Each morning they would be given seven tasks to perform at rest, and then while cycling. They were also asked to rate their sleepiness and mood before completing the tasks.
The results showed the effects of three nights of partial sleep on executive functions were inconsistent. The paper says an explanation for this could be that some people are more resilient to a mild or moderate sleep deficit. However, regardless of sleep status, moderate-intensity exercise improved performance across all the tasks.
In the second experiment, participants went an entire night without sleep and were then put in an hypoxic (low levels of oxygen) environment at the University’s Extreme Environment Labs. Despite oxygen levels being lowered, exercise continued to improve cognitive performance.
Co-lead author, Dr Thomas Williams from the University’s Extreme Environments Research Group, explained why the team decided to examine a combination of stressors for the study: “Sleep deprivation is often experienced in combination with other stressors. For example, people who travel to high altitude are also likely to experience a disruption to their sleep pattern.
“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.”
The paper says explanations for why CP improves during exercise – even when a person’s sleep deprived and low on oxygen – could be changes to the amount of brain regulating hormones, as well as a number of psychophysiological factors including cerebral blood flow, arousal and motivation.
It suggests that cognitive performance is not solely dependent upon the Prefrontal Cortex (PFC) area of the brain, despite it playing an integral role in the performance of tasks.
“The PFC is highly sensitive to its neurochemical environment and is highly susceptible to stress”, explained co-lead author Juan Ignacio Badariotti from the University’s Department of Psychology.
“It regulates our thoughts, actions and emotions and is considered to be the primary part of the brain associated with executive functions.
“But our findings suggest the mechanisms behind CP 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.”
The paper recommends further investigation to reveal what neurobiological mechanisms are behind the cognitive function process. This discovery would support anyone who experiences broken sleep or low oxygen, including climbers and skiers, but also parents of young children and shift workers.
The authors also recognise only healthy, young people were included in this study, and several individuals were withdrawn due to adverse events. They hope to carry out further investigation into the relationship between CP and stressors, with a broader mix of participants.
The study was a collaboration between the University of Portsmouth, University of Chichester, University of Surrey, Teesside University, The University of Electro-Communications in Tokyo, Japan, and Sao Paulo State University in Brazil.
About this exercise, sleep, and neuroscience research news
Author: Robyn Montague
Source: University of Portsmouth
Contact: Robyn Montague – University of Portsmouth
Image: The image is credited to Neuroscience News
Original Research: Open access.
“The Effects of Sleep Deprivation, Acute Hypoxia, and Exercise on Cognitive Performance: A Multi-Experiment Combined Stressors Study” by Joe Costello et al. Physiology and Behavior
Abstract
The Effects of Sleep Deprivation, Acute Hypoxia, and Exercise on Cognitive Performance: A Multi-Experiment Combined Stressors Study
Introduction
Both sleep deprivation and hypoxia have been shown to impair executive function. Conversely, moderate intensity exercise is known to improve executive function. In a multi-experiment study, we tested the hypotheses that moderate intensity exercise would ameliorate any decline in executive function after i) three consecutive nights of partial sleep deprivation (PSD) (Experiment 1) and ii) the isolated and combined effects of a single night of total sleep deprivation (TSD) and acute hypoxia (Experiment 2).
Methods
Using a rigorous randomised controlled crossover design, 12 healthy participants volunteered in each experiment (24 total, 5 females). In both experiments seven executive function (2-choice reaction time, logical relations, manikin, mathematical processing, 1-back, 2-back, 3-back) tasks of were completed at rest and during 20-min semi-recumbent, moderate intensity cycling. Tasks were completed in the following conditions: before and after three consecutive nights of PSD and habitual sleep (Experiment 1) and in normoxia and acute hypoxia (FIO2 = 0.12) following one night of habitual sleep and one night of TSD (Experiment 2).
Results
Although the effects of three nights of PSD on executive functions were inconsistent, one night of TSD (regardless of hypoxic status) reduced executive functions. Significantly, regardless of sleep or hypoxic status, executive functions are improved during an acute bout of moderate intensity exercise.
Conclusion
These novel data indicate that moderate intensity exercise improves executive function performance after both PSD and TSD, regardless of hypoxic status. The key determinants and/or mechanism(s) responsible for this improvement still need to be elucidated. Future work should seek to identify these mechanisms and translate these significant findings into occupational and skilled performance settings.
