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HomeHealth & FitnessStop mental fatigue: Science reveals why thinking drains you and how to fight back

Stop mental fatigue: Science reveals why thinking drains you and how to fight back

New scientific investigations suggest that mental fatigue is far more than a passing feeling, it may be a biological signal that the brain is reaching its metabolic limits. Researchers say this understanding could reshape how we diagnose and treat chronic exhaustion, from burnout to long-term illness.

December 11, 2025 / 08:48 IST
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Heavy decision-making, creativity or novelty appear to drain resources faster than repetitive or familiar work. (Picture Credit: Pexels)

For years, scientists treated mental fatigue as a vague concept. Now, thanks to advances in brain-imaging and metabolic studies, cognitive exhaustion is being examined with the same seriousness once reserved for muscle fatigue. Instead of viewing tiredness as a lack of focus or willpower, scientists are beginning to map it to real biological markers, shifts in neural chemistry, energy use, and activity patterns signalling that the brain is running low on fuel.

This new approach is opening up possibilities for understanding conditions like chronic fatigue syndrome, depression and long COVID, where people report lingering mental exhaustion long after their physical symptoms have eased. If the brain’s “engine” is struggling to keep up with demand, researchers argue, then therapies might be designed to support recovery rather than simply encouraging people to “power through.” And that, many say, could be a welcome shift from decades of dismissing exhaustion as mere mood or laziness.

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Researchers notice that tasks that involve heavy decision-making, creativity or novelty appear to drain resources faster than repetitive or familiar work. It helps explain why a morning of intense problem-solving can leave a person feeling far more shattered than several hours of routine admin.
Here are signs your brain may be exhausted: