Elsevier

Applied Ergonomics

Volume 63, September 2017, Pages 9-16
Applied Ergonomics

Performance awareness: Predicting cognitive performance during simulated shiftwork using chronobiological measures

https://doi.org/10.1016/j.apergo.2017.03.009Get rights and content

Highlights

  • A new metric was developed to assess an individual's awareness of their own performance.

  • A simulated sleep deprived day shift and sleep deprived night shift condition was used.

  • Heart rate and body temperature were used to index the endogenous circadian rhythm.

  • The performance awareness metric paralleled the circadian body temperature.

  • Physiological tracers predicted performance awareness better than self-report.

Abstract

Physiological tracers of circadian rhythms and a performance awareness index were examined as predictors of cognitive performance during two sleep deprivation conditions common to occupational shiftwork. Study 1: Thirty-three sleep-deprived participants completed a simulated nightshift. Study 2: Thirty-two partially sleep-deprived participants completed a simulated dayshift. A standardized logic test was used to measure cognitive performance. Body temperature and heart rate were measured as chronobiological indices of endogenous circadian rhythms. Performance awareness was calculated as a correlation between actual and perceived performance. These studies demonstrated a parallelism between performance awareness and the circadian rhythm. Chronobiological changes were predictive of performance awareness during the simulated nightshift but not dayshift. Only oral temperature was a significant independent predictor. Oral temperature predicted an individual's awareness of their own performance better than their own subjective awareness. These findings suggest that using circadian rhythms in applied ergonomics may reduce occupational risk due to low performance awareness.

Introduction

Endogenous circadian rhythms are intrinsically connected with cognitive performance and applied ergonomics through alertness (Van Dongen and Dinges, 2000). This relationship is significant when considering the effects of shiftwork scheduling on the sleep/wake cycle and the detrimental effects resulting from sleep deprivation (Pilcher and Huffcutt, 1996). As a result, circadian rhythms are of utmost importance when considering on-the-job safety and may be used to mitigate occupational risks (Costa, 1996).

Cognitive performance can fluctuate across a work shift due to circadian rhythms. Periods of poor cognitive performance occur as a result of a nonlinear interaction between the pressure to sleep, the need to stay awake, and biological rhythms (Van Dongen and Dinges, 2003). This results in a cognitive performance low, or circadian decrease, when the hormone melatonin increases and body temperature decreases during nightshift hours (Wyatt et al., 1999). In the case of repeated nightshifts, further cognitive performance decrements are also associated with sleep deprivation following sustained wakefulness during the circadian decrease (Monk et al., 1985, Olds and Clarke, 2010). Not surprising then, the circadian decrease and occupational risk during nightshift are commonly correlated (Folkard et al., 2006, Wojtczak-Jaroszowa and Jarosz, 1987), and sleep deprivation during the circadian decrease limits work-related attention, memory, vigilance, motivation, and subjective perceptions (Odle-Dusseau et al., 2010, Pilcher et al., 2007). Indeed, occupational safety research and circadian rhythm research exist as concomitant fields when exploring cognitive performance.

Because of the effect of circadian rhythms on cognitive performance, methods of tracking biological changes in a non-invasive manner could be advantageous to the field of applied ergonomics. Literature shows that core temperature and heart rate changes can be used as indices of endogenous circadian rhythms (Krauchi and Wirz-Justice, 1994, Walker et al., 2009), and could be applied to an occupational setting as a tracer of dangerous cognitive decrement. Furthermore, circadian changes in core body temperature has been shown to parallel occupational risk factors such as alertness, sleepiness, serial search ability, and general cognitive performance (Burgess et al., 2003, Darwent et al., 2010, Dijk et al., 1992, Monk et al., 1985, Wyatt et al., 1999). Cardiac activity has also been shown to parallel occupational risk factors like attention, but has not been proposed within an occupational setting (Van Eekelen et al., 2004, Walker et al., 2009). Such a parallel relationship between overt biological markers and occupational risk is an important topic for the workforce at large.

This relationship may be more important when considering the exacerbating effects of sleep deprivation on cognitive performance during shiftwork. Shiftwork schedules can cause partial sleep deprivation (i.e., insufficient/limited sleep at night) during the dayshift and more severe total sleep deprivation (i.e., no sleep at night) during a nightshift when day sleep is difficult, and may influence the biological circadian cycle (Daan et al., 1984, McClelland et al., 2013). Sleep deprivation holistically limits cognitive and motor performance and can even impact brain operational capacity after recovery days of normal sleep (Belenky et al., 2003, Morris et al., 2015, Pilcher et al., 2015a, Pilcher et al., 2015b). Importantly, research also suggests that sleep deprivation impacts metacognition, limiting an individual's awareness and understanding of their own cognitive decrements (Odle-Dusseau et al., 2010). As a result, sleep deprivation must be considered when addressing occupational risks related to circadian rhythms.

Poor cognitive performance impacts both employee and employer (Eatough et al., 2011), largely due to degradation in monitoring vigilance during sleep deprivation. Laboratory simulations of shiftwork have shown high variability in tasks requiring monitoring vigilance between dayshift and nightshift due to partial sleep deprivation (Sauer et al., 2003). In addition, an employee's awareness of their own performance (i.e., self-monitoring) can have a significant effect on the quality of their work as well as their own safety within the work place (Slovic, 1978, Stanton et al., 2001). Research has explored the parallel relationship between circadian rhythms and cognitive performance, but has not done so in direct comparison to the two basic types of occupational sleep deprivation: total deprivation during nightshift work and partial deprivation during dayshift work (Pilcher and Huffcutt, 1996). Research has also demonstrated the effects of occupational sleep deprivation on metacognition, but has not shown the parallel relationship with circadian rhythms that other cognitive measures have (Dorrian et al., 2000, Dorrian et al., 2003, Monk et al., 1985). This relationship between the circadian cycle and an employee's metacognition would be important to occupational safety and productivity but remains enigmatic. If this relationship exists, the potential to predict performance awareness using physiological circadian rhythm markers may also exists, which could be used to reduce occupational risk (Folkard et al., 2006, Knauth, 1996, Monk et al., 1996).

The authors propose performance awareness as a metacognitive index to better understand the impact of circadian rhythms and sleep deprivation on occupational work. The performance awareness index is based on perceived task performance and actual task performance, the former sharing a metacognitive relationship with the latter. High performance awareness does not necessarily equate to good task performance, but rather a high awareness of actual task performance, either good or bad. This is an important distinction which suggests personal performance may only have the potential to be self-corrected during times of high performance awareness. Previous studies have used a correlational approach to index self-awareness and distraction, but have not used it to assess changes in awareness (Horrey et al., 2008). These studies have, instead, focused on the existence of performance awareness denoted by the significance of the correlation. Moreover, this method has not been used to assess performance difference related to the circadian rhythm or shiftwork.

Two common types of sleep deprivation, total sleep deprivation during a simulated nightshift and partial sleep deprivation during a simulated dayshift, were used in two separate laboratory studies. We hypothesize that individuals will lose the ability to accurately gauge self-performance in parallel with both types of sleep deprivation, resulting in low performance awareness scores. However, we anticipate those in the total sleep deprivation condition will show a greater degree of performance awareness degradation. We also hypothesize that physiological measures of heart rate and oral temperature will be significant predictors of performance awareness in both shift conditions. Both cognitive performance and physiological changes have been shown to parallel the circadian rhythm which suggests that one should be able predict the other.

Section snippets

Participants

A sample of thirty-three volunteers (22 males and 11 females) with a mean age of 20.57 (SD = 2.70) participated in a simulated nightshift under sleep deprivation conditions. Participants were screened using a questionnaire prior to testing to ensure they were in good mental and physical health, native English speakers, and had no history of sleep disorders. The procedure was explained prior to participation and individuals received monetary compensation ($150) for their participation over two

Study 1

Study 1 required that participants be well rested before laboratory testing. On the three nights prior to arriving at the laboratory, participants reported sleeping an average of 7 h and 11 min (SD = 1.25 h). Data from the actigraph supported a similar sleep quantity (7 h and 16 min, SD = 1.30 h), suggesting participants were well rested. Participants were not allowed to sleep once they arrived to the laboratory.

The results of a RM ANOVA showed a significant main effect of testing session (F

Discussion

This study examined a correlational performance awareness index during total and partial sleep deprivation conditions. A simulated nightshift under total sleep deprivation conditions significantly impaired participants’ awareness of their own performance on a complex cognitive task, supported by a low performance awareness correlation during the circadian decrease. The decrement in performance awareness was predicted by endogenous circadian rhythms as measured through oral temperature and heart

Conclusion

A correlational performance awareness index is used to better understand metacognition of performance and the impact of circadian rhythms under total and partial sleep deprivation conditions. The study also demonstrates a parallelism between performance awareness and the circadian rhythm. The current study suggests that total sleep deprivation combined with working at night negatively impacts performance awareness on cognitive tasks. This effect is not seen during partial sleep deprivation

Conflict of interest

The authors have no conflict of interest to disclose.

Acknowledgments

This project was partially supported by the Center for Advanced Study of Language, University of Maryland, College Park, Maryland, USA. We thank Dr. James A. McCubbin for his effort in the initial formation of the research collaboration with the Center for Advanced Study of Language and the off-campus research laboratory. We also thank our research staff, graduate students, and undergraduate students at Clemson University for their assistance in data gathering and data management including:

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