Shift Work and Cognitive Flexibility: Decomposing Task Performance

Abstract

Deficits in cognitive functioning associated with shift work are particularly relevant to occupational performance; however, few studies have examined how cognitive functioning is associated with specific components of shift work. This observational study examined how circadian phase, nocturnal sleepiness, and daytime insomnia in a sample of shift workers ( N = 30) were associated with cognitive flexibility during the night shift. Cognitive flexibility was measured using a computerized task-switching paradigm, which produces 2 indexes of flexibility: switch cost and set inhibition. Switch cost represents the additional cognitive effort required in switching to a different task and can impact performance when multitasking is involved. Set inhibition is the efficiency in returning to previously completed tasks and represents the degree of cognitive perseveration, which can lead to reduced accuracy. Circadian phase was measured via melatonin assays, nocturnal sleepiness was assessed using the Multiple Sleep Latency Test, and daytime insomnia was assessed using the Insomnia Severity Index. Results indicated that those with an earlier circadian phase, insomnia, and sleepiness exhibited reduced cognitive flexibility; however, specific components of cognitive flexibility were differentially associated with circadian phase, insomnia, and sleepiness. Individuals with an earlier circadian phase (thus more misaligned to the night shift) exhibited larger switch costs, which was also associated with reduced task efficiency. Shift workers with more daytime insomnia demonstrated difficulties with cognitive inhibition, whereas nocturnal sleepiness was associated with difficulties in reactivating previous tasks. Deficits in set inhibition were also related to reduced accuracy and increased perseverative errors. Together, this study indicates that task performance deficits in shift work are complex and are variably impacted by different mechanisms. Future research may examine phenotypic differences in shift work and the associated consequences. Results also suggest that fatigue risk management strategies may benefit from increased scope and specificity in assessment of sleep, sleepiness, and circadian rhythms in shift workers.

Daily circadian misalignment impairs human cognitive performance task-dependently

“…Furthermore, most of our current understanding of cognitive vulnerability at night builds mostly upon dynamics within a single 2 4-h period 13 , 16 , 17 , whereas the effects of circadian misalignment on cognition in shift work are typically experienced over multiple days , which limits the translation of these circadian protocols into real-life settings. Secondly, most controlled simulated night work studies have primarily tested cognitive function within a single domain, which is attention resources 18 – 21 , while in shift work many different cognitive domains are being taxed, dependent on specific components of the work, including cognitive flexibility 22 . Given that task-specific cognitive brain responses show different 24-h dynamics 13 , it is unlikely that all cognitive domains will be (equally) jeopardized over 24-h and with repeated night work.…”

Effects of sleep deprivation on executive functioning, cognitive abilities, metacognitive confidence, and decision making

“…The negative impact of fatigue on decision performance (Aidman, Chadunow, Johnson, & Reece, ; Jackson, Kleitman, & Aidman, ; Johnson et al, ; Pilcher & Huffcutt, ) has been consistently reported as a primary factor underlying the decision errors that can lead to real‐world catastrophes. Decision making is known to be affected by the output of cognitive processing and by metacognitive monitoring and control of decision behaviours (e.g., Ackerman & Wolman, ; Cheng, Tallent, Bender, Tran, & Drake, ; Jackson, Kleitman, Stankov, & Howie, ; Koriat & Goldsmith, ; Stanovich & West, ; Thompson, Turner, & Pennycook, ). Thus, fatigue may affect decision performance not only by degrading its underpinning cognitive processing but also by disrupting the metacognitive ability to monitor and regulate decision actions.…”

“…Thus, fatigue may affect decision performance not only by degrading its underpinning cognitive processing but also by disrupting the metacognitive ability to monitor and regulate decision actions. However, the combined influence of cognitive ability and metacognitive processes on decision making under sleep deprivation conditions is not well understood (Cheng et al, ; Jackson, Martin, Aidman, & Kleitman, ). Our study aimed at experimentally examining the effect of acute sleep deprivation on metacognitive constructs and decision making in addition to executive functions and cognitive abilities.…”

Shift work and sleep: medical implications and management

“…66 Shift workers have a cognitive decline and impaired work efficiency compared to non-shift workers. 5 Disturbed sleep can cause drowsiness, which is a major cause of road traffic accidents. 67 Figure 1 shift work associated pathologies and comorbidities.…”

“…4 The poor sleep that results from disruption of circadian rhythms can lead to cognitive impairment and work under-performance; this can be overcome with good social support and a supportive work environment. 5 Preventive measures to reduce psychosocial stress at work places such as family support, social support and better work environment can decrease sleep problems and a worker can then be more efficient and productive during working hours. 6…”