Motivation depends on how brain processes fatigue

How do we decide whether or not an activity which requires work is ‘worth the effort?’ Researchers at the University of Birmingham & University of Oxford have shown that the willingness to work is not static, and depends upon the fluctuating rhythms of fatigue.

Fatigue – the feeling of exhaustion from doing effortful tasks – is something we all experience daily. It makes us lose motivation and want to take a break. Although scientists understand the mechanisms the brain uses to decide whether a given task is worth the effort, the influence of fatigue on this process is not yet well understood.

The research team conducted a study to investigate the impact of fatigue on a person’s decision to exert effort. They found that people were less likely to work and exert effort – even for a reward – if they were fatigued. The results are published in Nature Communications.

Intriguingly, the researchers found that there were two different types of fatigue that were detected in distinct parts of the brain. In the first, fatigue is experienced as a short-term feeling, which can be overcome after a short rest. Over time, however, a second, longer term feeling builds up, stops people from wanting to work, and doesn’t go away with short rests.