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Diurnal trends in mood and performance do not all parallel alertness
D S Owens1, I Macdonald, P Tucker
1Body Rhythms and Shiftwork Centre, Department of Psychology, University of Wales Swansea, United Kingdom. d.s.owen@swansea.ac.uk
Scandinavian Journal of Work, Environment & Health
|January 23, 1999
Summary
Alertness can predict some performance measures, particularly simple perceptual-motor speed. However, caution is advised when using alertness to predict other performance capabilities due to varying time-of-day effects.
Area of Science:
- Chronobiology
- Cognitive Psychology
- Human Performance
Background:
- Understanding time-of-day effects on human performance is crucial for optimizing work schedules and safety.
- Alertness is a key factor influencing cognitive and motor functions throughout the day.
Purpose of the Study:
- To investigate whether alertness levels can accurately predict time-of-day variations in different performance measures.
- To assess the relationship between alertness and specific cognitive and psychomotor tasks.
Main Methods:
- 24 highly practiced young women underwent a controlled sleep-wake schedule for 6-7 days.
- Performance and mood tests, including serial reaction time and memory scanning, were administered every 2 hours.
- Continuous rectal temperature monitoring was used to assess physiological circadian rhythms.
Main Results:
- Cross-correlations showed alertness predicted simple perceptual-motor speed but was less accurate for other measures.
- Time-of-day trends for all performance measures differed significantly from alertness trends.
- The discrepancy between alertness and performance trends was substantial for some measures, particularly at the end of the day.
Conclusions:
- Alertness serves as a reliable predictor for specific performance capabilities, notably simple perceptual-motor speed.
- Extrapolating alertness as a universal predictor for all performance measures requires careful consideration.
- Individual differences and task complexity influence the predictive validity of alertness on performance.