# Changes in higher order cognitive function between four watch keeping schedules

## TL;DR

This study compares how different work-rest schedules affect higher-level thinking skills in a simulated maritime environment.

## Contribution

The study introduces a novel comparison of four maritime watch schedules using real-time cognitive assessments.

## Key findings

- Condition B (6/6 schedule) showed the worst cognitive performance across most tasks.
- Condition A (8/8/4/4) had the least stable cognitive function during waking hours.
- Variability in cognitive performance was observed across different watch schedules.

## Abstract

Maritime industries utilize many different watch keeping schedules to maintain vigilance and crew safety around the clock. These schedules can be fatiguing, negatively impacting vigilant attention. This has led to the consideration of schedules that might allow for more sleep time, but how these schedules impact higher order cognitive function remains unclear. These schedules require assessment with tasks that are relevant to real-world operations on maritime vessels. This study investigated the effect of four schedules on higher order cognitive function. N = 27 (16 female) participants were recruited to a 10-day laboratory study, comparing four schedules. The schedules investigated were eight-on/eight-off/four-on/four-off (8/8/4/4) with sleep from 09:30 to 16:00 (condition A); six-on/six-off (6/6) with sleep from 08:30 to 12:30 and 21:30 to 00:00 (condition B); four-on/four-off (4/4/4/4/4/4) with sleep from 18:00 to 00:30 (condition C); and four-on/four-off (4/4/4/4/4/4) with sleep from 01:30 to 08:00 (condition D). Higher order cognitive function was assessed 2–3× daily whilst “on watch” using tests of visual scanning, learning, working memory, mental flexibility, and visuomotor control. Conditions were ranked and stability of performance on watch was compared between conditions using Kruskal–Wallis tests. Cognitive function within condition B was ranked the worst for most of the tasks. However, the stability of higher order cognitive function was poorest across the waking day within condition A. These findings highlight the variability in cognitive capacities during different watch keeping schedules.