Acute effects of a simulated quick return on subjective sleepiness, mood, and cognitive performance: A laboratory crossover controlled trial.

Sleep loss due to short time off between shifts has been proposed as a mechanism contributing to impaired functioning in occupational settings. This laboratory crossover trial (ClinicalTrials.gov identifier: NCT05162105, N = 66) compared subjective sleepiness, mood, and cognitive performance on a day shift after an evening shift with only 8 h off between shifts (quick return, QR) to a day shift after another day shift with 16 h off between shifts (control). Results indicated higher subjective sleepiness (Karolinska Sleepiness Scale) during the QR condition compared to the control condition (p < 0.001). No significant differences were found on mood (Positive and Negative Affect Schedule) and cognitive performance (Psychomotor Vigilance- and Digit Symbol Substitution Test) between the conditions. Findings of increased subjective sleepiness corroborate previous field studies. This trial is to our knowledge the first to compare mood and cognitive performance after a QR to a longer shift transition using an experimental design. Future research should explore the effects of accumulated sleep loss associated with QRs (e.g. having several QRs within a short time period) on behavioral outcomes.