Mental fatigue: Costs and benefits

Abstract

A framework for mental fatigue is proposed, that involves an integrated evaluation of both expected rewards and energetical costs associated with continued performance. Adequate evaluation of predicted rewards and potential risks of actions is essential for successful adaptive behaviour. However, while both rewards and punishments can motivate to engage in activities, both types of motivated behaviour are associated with energetical costs. We will review findings that suggest that the nucleus accumbens, orbitofrontal cortex, amygdala, insula and anterior cingulate cortex are involved evaluating both the potential rewards associated with performing a task, as well as assessing the energetical demands involved in task performance. Behaviour will only proceed if this evaluation turns out favourably towards spending (additional) energy. We propose that this evaluation of predicted rewards and energetical costs is central to the phenomenon of mental fatigue: people will no longer be motivated to engage in task performance when energetical costs are perceived to outweigh predicted rewards.

The role of awakening cortisol and psychological distress in diurnal variations in affect: A day reconstruction study.

“…chronic fatigue, burnout) and low mood levels (e.g. post-traumatic stress, melancholic depression) tend to have reduced cortisol levels in the period after waking (Boksem & Tops, 2009). Furthermore, our analyses suggest that the divergent diurnal patterns of affect predicted by morning cortisol levels were unlikely to be explained by activity patterns, environmental changes or baseline health or health behavior differences.…”

Fatores clínicos, funcionais e inflamatórios associados à fadiga muscular e à fadiga autopercebida em idosas da comunidade

“…Fatigue sensation may be related to physical alterations and modifications to mental and emotional status. The context of this approach is multifactorial 1,8 . The conscious self-report of tiredness is the most important information for the evaluation of fatigue under the psychological and subjective perspective 2 .…”

Cortisol and induced cognitive fatigue: Effects on memory activation in healthy males

“…Given that responders showed greater cortisol and fatigue levels in response to the sustained performance of demanding tasks in our study, their ratings in relation to feelings of fatigue over the last week may indicate that they also experienced increased cortisol and fatigue levels in response to the performance of demanding tasks in everyday life. Such frequent high cortisol responses are thought to be a precursor to the allostatic down-regulation of the HPA axis seen in chronic fatigue (Boksem & Tops, 2008). Therefore, cortisol responders in our study may represent an intermediary stage where cortisol reactivity is elevated and some more long-term differences have begun to appear, such as lower vigor levels following a demanding working week as a school teacher.…”

“…Hence, in the short-term (minutes to hours), cortisol is thought to elicit energy mobilization and an associated decrease in perceived fatigue as part of a generally adaptive response called allostasis (McEwen, 2007). However, in the longterm (weeks to months), frequent high cortisol levels in association with chronic stress or 'allostatic load' (McEwen, 2007) may lead to downregulation of the HPA axis, reflected in decreased cortisol levels and reactivity, and ensuing chronic fatigue (Boksem & Tops, 2008). …”