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Objectives The purpose of this study was to investigate the accumulation of fatigue over a two-week offshore period. In particular, the effects of (1) time-of-day and days-on-shift as well as (2) acute and chronic sleep loss on the rate at which fatigue accumulates were investigated. Methods 42 day-shift offshore workers were examined. Fatigue was measured using pre- and post-shift scores on the Karolinska Sleepiness Scale (KSS). Total sleep time was measured using actigraphy (Motionwatch8, Camntech). Data was analyzed using a linear mixed model analyses. Results Average sleep loss per night was 92 min (95%CI: 89.6-94.0; p <.001). Mean cumulative sleep loss across the study was 21:20hrs (SD = 08:10hrs) over the 14 days. Chronic sleep loss was significantly related to a modest increase in sleepiness (KSS) across the shift (95%CI: 0.01-0.17; p =.020) and in post-shift scores (95%CI:.07-0.19; p <.001). Time-of-day (95%CI: 0.63 to 0.01; p =.042) and days-on-shift (95%CI: 0.03-0.08; p <.001) as well as their interaction (95%CI: 0.08 to 0.00; p =.027) influenced the rate at which fatigue accumulated over a two-week offshore period. Conclusions Pre- and post-shift fatigue accumulate in different ways over the two-week offshore period. The accumulation of post-shift fatigue scores was positively related to successive days-on-shift and chronic sleep loss. Our results suggest that prolonging offshore periods will likely result in elevated fatigue risk. Accumulating fatigue and sleep loss over two-week offshore periods should be considered in fatigue risk management plans and systems.

Objectives: This study examines the impacts of peak summer demand on operator workload and fatigue in a maritime environment. Methods: Participants (n = 12) were senior shipboard personnel who were working during the summer double sailing period for a roll-on roll-off ferry service. Wrist actigraphy was used to determine sleep opportunity and sleep duration, as well as prior sleep, total wake time, performance and alertness at the beginning and end of work periods. Results: Contrary to expectations, sleep was significantly greater, and both subjective estimates of fatigue and objective neurobehavioral performance were not impacted negatively by periods of increased work intensity. Conclusions: This study highlights a number of features of a fatigue-risk management system that appear to have been instrumental in ensuring adequate sleep and performance was maintained throughout periods of increased operational intensity. As a simple colloquial description of the fatigue-risk management system at play in this operation, it was fine to work hard if you were able to sleep hard as well.

This study investigates the effect of passenger and phone conversations on sleep-restricted driving. Six volunteers (50% male, mean age 24.8 +/- 4.3years) had their sleep restricted to 4h in bed followed by a 20-min simulated drive on three separate occasions. Each drive included either a passenger conversation, a mobile phone conversation or a quiet passenger. The effect size of a phone conversation on lane deviation was large while passenger conversation was small. The main effect of conversation on lane deviation was non-significant (F(2,10)=2.57, p=0.126). Combining sleep-restricted driving with conversations warrants further investigation.