Is your brain tired? Researchers are discovering the roots of mental fatigue

Summary & key facts

This Nature news feature by Lynne Peeples (10 December 2025) looks at new research on mental fatigue — why thinking hard can make people feel worn out. It explains that scientists are trying to build better ways to measure cognitive exhaustion. The article says those better measures could help point to treatments for long COVID and other disabling conditions.

Key facts:

• Title: "Is your brain tired? Researchers are discovering the roots of mental fatigue."
• Author: Lynne Peeples. Published 10 December 2025 in Nature (volume 648, pages 262–264). DOI: https://doi.org/10.1038/d41586-025-03974-w.
• The article says researchers are working on better ways to measure cognitive exhaustion (mental fatigue).
• The article states that improved measures of mental fatigue could point to treatments for long COVID and other debilitating disorders (language in the article uses "could" to indicate possibility, not certainty).
• The piece opens with a quote from chess grandmaster Garry Kasparov about feeling "really tired" during his 1996 matches with IBM’s Deep Blue, as an example of subjective mental fatigue.
• The article cites recent research spanning years 2016–2025, including studies by Pessiglione et al. (2025), ElGrawani et al. (2024), and Wiehler et al. (2022).

Topics

COVID-19 and Mental Health Intensive Care Unit Cognitive Disorders Long-Term Effects of COVID-19

Categories

Health Sciences Medicine Neurology

Tags

2019-20 coronavirus outbreak Applied psychology Burnout Clinical psychology Cognition Cognitive psychology Coronavirus disease 2019 (COVID-19) Measure (data warehouse) Medicine MEDLINE Mental fatigue Mental health Mental illness Point (geometry) Psychiatry Psychology Self-report study Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)