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What does mental fatigue look like?

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  • mental fatigue

By Lynn Celmer  |  Dec 12, 2012
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We all perhaps know the feeling of mental exhaustion, but what does it mean physiologically to have mental fatigue? A new study carried out using brain scans could help scientists uncover the neurobiological mechanisms underlying mental fatigue.

Mental fatigue has become commonplace as many people face increasing mental demands from stressful jobs, longer working hours with less time to relax and increasingly suffer sleep problems, according to study authors Bui Ha Duc and Xiaoping Li of the National University of Singapore.

The study will be published in an upcoming issue of the International Journal of Computer Applications in Technology. The researchers used functional magnetic resonance imaging (fMRI) to monitor activity in the brains of 10 student volunteers (male and female ages 19 to 25) deprived of sleep for 25 hours and given a simple task repeatedly throughout that period. They carried out scans at 9 a.m., 2p.m., 3 a.m. and 9a.m. the following day. All volunteers had avoided alcohol and caffeine for the 24-hours prior to the experiment, were all physically and mentally fit prior to participation and none had any sleep problems.

The activation of the left thalamus increases with sleep deprivation, going exactly the opposite trend to the inferior parietal that (following the circadian rhythm) decreases in activation from 9 a.m. to 3 a.m. the next day and then increases in activation.

The team explains that a gradual increase in mental fatigue led to decreased activity in the volunteers’ brains in specific regions: The anterior cingulate gyrus, right inferior frontal, left middle frontal and right superior temporal cortex. The anterior cingulate cortex has been described as an interface between motivation, cognition and action, and has been implicated in using reinforcement information to control behavior. The fMRI scans suggest that decreased activity in this part of the brain is therefore linked to those familiar feelings of mental fatigue including lethargy and slowness of thinking.

“The research provides a neurophysiologic basis for measuring the level of mental fatigue by EEG, as well as for the intervention by non-invasive neural stimulation to maintain wakefulness,” the team says.

If you’re suffering from mental fatigue, the AASM encourages you to talk to your doctors about your sleep problems or view our searchable directory of sleep centers

1 Comment

  1. 1 Lynn Reid 21 Feb
    So would these findings be duplicated in Hypersomnia patients?