Bright light exposure during simulated night work improves cognitive flexibility

ABSTRACT

Night work leads to sleepiness and reduced vigilant attention during work hours, and bright light interventions may reduce such effects. It is also known that total sleep deprivation impairs cognitive flexibility as measured by reversal learning tasks. Whether night work impairs reversal learning task performance or if bright light can mitigate reversal learning deficits during night work is unclear. In this counterbalanced crossover study (ClinicaTrials.gov Identifier NCT03203538), young healthy individuals completed a reversal learning task twice during each of three consecutive simulated night shifts (23:00–07:00 h). The night shifts were performed in a laboratory under a full-spectrum (4000 K) bright light (~900 lx) and a standard light (~90 lx) condition. Reversal learning task performance was reduced towards the end of the night shifts (04:50 h), compared to the first part of the night shifts (00:20 h) in both light conditions. However, with bright light, the reversal learning task performance improved towards the end of the night shifts, compared to standard light. The study shows that bright light may mitigate performance deficits on a reversal learning task during night work and implies that bright light interventions during night work may be beneficial not only for vigilant attention but also for cognitive flexibility.

KEYWORDS:

• Cognitive control
• decision making
• reversal learning
• working memory
• task switch
• sleep deprivation
• light emitting diode
• LED

Acknowledgements

We would like to thank the participants for their time and contribution to this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request. e-mail:[email protected]

Additional information

Funding

The study was supported by a PhD grant (Faculty of Psychology, University of Bergen, Norway) for ES and TP. The experiment was conducted in the laboratory facilities at the Faculty of Psychology, University of Bergen, Norway. The LED-luminaires in the laboratory were provided by Glamox AS, BU Norge, free of charge. Glamox AS had no part in the study design, data collection, analysis, decision to publish or manuscript preparation.