Acute mental fatigue slows reaction time, at least in athletes
In a study of 64 athletes, 15 minutes of a demanding color-naming task (the Stroop test) was used to induce short-term mental fatigue. Reaction time to visual stimuli increased significantly from before to after the task, and the slowdown was similar in men and women. [4] The same study found no significant change in heart rate after the task, which the authors interpret as a possible shift toward parasympathetic (relaxation) activity accompanying the mental fatigue. [4]
A separate study of construction workers used a digital reaction timer as an objective fatigue indicator and found that reaction time could distinguish fatigue levels and that several biological and work-related variables were associated with slower reactions. [3] That study was cross-sectional, so it shows a link between fatigue and reaction time at one point in time rather than proving that fatigue causes the slowdown. [3]
Long-term fatigue is predicted by fatigue early on, not by thyroid hormone levels
In a nationwide study of patients with differentiated thyroid cancer, fatigue measured one year after treatment significantly predicted fatigue five years later, even after adjusting for other variables. [2] The authors conclude that patients reporting short-term fatigue are at higher risk of long-term fatigue, which supports early assessment after treatment to identify people who might benefit from intervention. [2]
The same study found no significant association between thyroid-stimulating hormone (TSH) levels and fatigue. [2] This matters for the short-term versus long-term question because it suggests that long-term fatigue in this group is not simply a matter of hormone control; it is better predicted by the person's earlier fatigue experience. [2]
Complex planning and decision errors are not yet compared across fatigue durations
None of the studies that measured cognitive performance examined complex planning or decision errors. The athlete study measured only simple reaction time to visual stimuli, and the construction-worker study used a reaction timer rather than a planning or decision task. [4][3] The thyroid-cancer study measured fatigue through a vitality questionnaire and did not test reaction time, planning, or decision-making. [2]
The two engineering papers on wind-turbine fatigue are about structural damage in metal and composite materials, not about human cognition, so they cannot answer the question about reaction time, planning, or decision errors. [1][5] As a result, the honest answer is that the evidence supports a short-term fatigue effect on reaction time, and a predictive link from early to long-term fatigue, but it does not yet show whether short-term and long-term fatigue produce different patterns of planning failure or decision error.
Sources used in this answer
On short-term fatigue analysis for wind turbine tower of two semi-submersible wind turbines including effect of startup and shutdown processes Research papers
Startup and shutdown operations can increase short-term fatigue damage in wind turbine towers by 10% to 100%, and up to 200% in some conditions, with long-term importance depending on how often these events occur.
3004P Predictive factors of long-term fatigue in patients with differentiated thyroid cancer
In thyroid cancer patients, fatigue at one year after treatment significantly predicted fatigue at five years, while thyroid-stimulating hormone levels were not significantly associated with fatigue.
Reaction Time-Based Fatigue Analysis in Construction Workers
Digital reaction time measurement can differentiate fatigue levels in construction workers, and several biological and work-related variables were associated with increased reaction time.
Effects of Mental Fatigue on Reaction Time in Sportsmen
Fifteen minutes of a demanding cognitive task increased reaction time to visual stimuli in athletes, with no significant difference between men and women.
A Time-Domain Methodology for Nominal Stress-Based Fatigue Assessment of Semi-Submersible Floating Wind Turbine Hulls at Different Offshore Sites
A time-domain methodology was presented for assessing short- and long-term fatigue in floating wind turbine hulls across different offshore sites, identifying critical loading scenarios and fatigue-critical regions.