0631 Effect of Time-of-Day and Time-Spent-Awake on Objective and Self-Reported Measures of Performance in Police Officers Working Rotating Shifts

Shift work is associated with reduced sleep depending on the type of shift, leading to reduced alertness and increased sleepiness. The aim of the present study was to assess the effect of time-of-day and time-spent-awake on psychomotor performance and self-reported alertness and sleepiness in police officers involved in rotating shift work. Seventy-six police officers (20 women, 56 men) aged 32 ± 5.4 years (mean ± SD, range: 23-49) participated in a 35-day field study involving morning, evening, and night shifts (duration: 9- to 12-h). Multiple times per day, objective performance was measured using a 5-minute Psychomotor Vigilance Task (PVT). In addition, participants filled out a visual analog scale (VAS) to assess self-reported alertness and the Karolinska Sleepiness Scale (KSS) to assess self-reported sleepiness. The effect of time-of-day (TOD, 2-h or 4-h bins) and time-spent-awake adjusted for naps (TSAAN, 2-h bins) on all the variables was analyzed using linear mixed-effects modelling. A significant effect of TOD and TSAAN was found on all dependent measures. Based on TOD, the objective measures’ worst performance levels were observed between 0400 and 0800 hours, whereas for alertness and sleepiness the worst levels were observed between 0000 and 0200 hours. Based on TSAAN, the worst values were found at 17 h and 23 h of time awake, the last time bin used for objective performance and the self-reported measures, respectively. Our results suggest that time-of-day and time awake influence shift workers’ performance and self-reported alertness and sleepiness levels during shift work, potentially affecting their fitness for duty. Both objective and subjective measures were worst at night, although the specific TOD differed. This suggests that both types of measures address a slightly different aspect of vigilance. Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST)