What is it about?
People often push through tiredness to meet everyday mental demands, but this ability may have limits. Across six studies involving 1,088 people, participants who felt more fatigued than usual performed slightly worse on a test of mental speed. Greater fatigue and unusually fast performance also predicted a reduced ability to maintain performance when tired in the following hours. These findings suggest that both heightened fatigue and bursts of high mental effort may be early signs that a person will have more difficulty overcoming fatigue later on.
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Why is it important?
Experiencing greater-than-usual fatigue or performing mentally faster than usual may provide early warning that a person will have more difficulty maintaining performance while tired later on. Recognizing that periods of unusually fast thinking may be limited could help people use those periods strategically—for example, by prioritizing important meetings or complex decisions—and consider resting before their ability to push through fatigue declines. Further research is needed to test whether acting on these warning signs improves performance or reduces fatigue.
Perspectives
Fatigue is something we all contend with daily, which for us made the paper very interesting to work on. A takeaway message for me was that some ignoring of fatigue was fine, but ignoring it for too long may make its effect on processing speed less and less ignorable.
Raymond Hernandez
University of Southern California
Read the Original
This page is a summary of: Fatigue and processing speed predict subsequent fatigue override, evidence from a coordinated analysis of six EMA studies, Communications Psychology, September 2026, Springer Science + Business Media,
DOI: 10.1038/s44271-026-00537-1.
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