Deu na Nature Briefing
Why thinking hard makes us feel tired
Difficult tasks can lead to build-up of a signalling molecule in the brain, triggering fatigue.
It’s not just in your head: a desire to curl up on the couch after a day spent toiling at the computer could be a physiological response to mentally demanding work, according to a study that links mental fatigue to changes in brain metabolism.
The study, published on 11 August in Current Biology1, found that participants who spent more than six hours working on a tedious and mentally taxing assignment had higher levels of glutamate — an important signalling molecule in the brain. Too much glutamate can disrupt brain function, and a rest period could allow the brain to restore proper regulation of the molecule, the authors note. At the end of their work day, these study participants were also more likely than those who had performed easier tasks to opt for short-term, easily won financial rewards of lesser value than larger rewards that come after a longer wait or involve more effort.
The study is important in its effort to link cognitive fatigue with neurometabolism, says behavioural neuroscientist Carmen Sandi at the Swiss Federal Institute of Technology in Lausanne. But more research — potentially in non-human animals — will be needed to establish a causal link between feelings of exhaustion and metabolic changes in the brain, she adds. “It’s very good to start looking into this aspect,” says Sandi. “But for now this is an observation, which is a correlation.”
Tired brain (para texto completo acesse o link )
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