Full text is available at the source.
Sleep and Sleepiness of Fishermen on Rotating Schedules
Jun 7, 2008Chronobiology international
Sleep and tiredness in fishermen working rotating shifts
AI simplified
Abstract
Fishermen experienced < 4 hours of sleep on 23% of days at sea compared to 3% at home.
- Split sleep patterns were more prevalent at sea compared to at home.
- Median sleep duration was similar at sea (5.9 hours) and at home (6.7 hours).
- Post-sleep sleepiness ratings were higher at sea, with 24% of days rated > 7 compared to 9% at home.
- High acute sleep loss and residual sleepiness were more common during fishing trips at sea.
- The 12 h on/6 h off schedule may disrupt natural sleep patterns, contributing to fatigue.
AI simplified
Seafaring is a hazardous occupation with high death and injury rates, but the role of seafarer fatigue in these events is generally not well documented. The International Maritime Organization has identified seafarer fatigue as an important health and safety issue. Most research to date has focused on more regularly scheduled types of operations (e.g., merchant vessels, ferries), but there is relatively little information on commercial fishing, which often involves high day-to-day and seasonal variability in work patterns and workload. The present study was designed to monitor the sleep and sleepiness of commercial fishermen at home and during extended periods at sea during the peak of the hoki fishing season, with a view to developing better fatigue management strategies for this workforce. Sleep (wrist actigraphy and sleep diaries) and sleepiness (Karolinska Sleepiness Scale [KSS] before and after each sleep period) of 20 deckhands were monitored for 4-13 days at home and for 5-9 days at sea while working a nominal 12 h on/6 h off schedule. On the 12 h on/6 hoff schedule, there was still a clear preference for sleep at night. Comparing the last three days at home and the first three days at sea showed that fishermen were more likely to have split sleep at sea (Wilcoxon signed ranks p < 0.001), but the median sleep/24 h did not differ significantly by location (5.9 h at sea vs. 6.7 h at home). However, on 23% of days at sea, fishermen obtained < 4 h total sleep/24 h, compared to 3% of days at home ( p(chi 2) < 0.01). Sleep efficiency, mean activity counts/min sleep, and subjective ratings of sleep quality did not differ significantly between the last three days at home and the first three days at sea. However, sleepiness ratings remained higher after sleep at sea (Wilcoxon signed ranks p < 0.05), with fishermen having post-sleep KSS ratings >or= 7 on 24% of days at sea vs. 9% of days at home (Wilcoxon signed ranks p < 0.01). This work adds to the limited number of studies that objectively monitored the sleep of seafarers. It has the strength of operational fidelity but the weakness that large inter- and intra-individual variability in sleep, combined with the small sample size, limited the power of the study to detect statistically significant differences between sleep at home and at sea. The clear preference for sleep at night during the 12 h on/6 h off schedule at sea is consistent with the expectation that this 18 h duty/rest cycle is outside the range of entrainment of the circadian pacemaker. High levels of acute sleep loss, and residual sleepiness after sleep, were much more common at sea than at home. The longer duration of trips during the peak of the fishing season increases the risk of performance impairment due to greater cumulative sleep loss than would be expected on typical three-day trips. Key fatigue management strategies in this environment include that fishermen report to work as well rested as possible. Once at sea, the day-to-day variability in activities due to uncontrollable factors, such as fishing success, repairing gear, and weather conditions, mean that contingency planning is required for managing situations where the entire crew have experienced long periods of intensive work with minimum recovery opportunities.
Related papers
Dec '06
Sleepiness and sleep patterns during a simulated watch schedule of six hours on and six hours off at sea
top 30% journal
cited by 47 papers
journal article
Feb '16
How splitting sleep into 6-hour blocks affects thinking, sleep quality, and tiredness
top 20% journal
cited by 27 papers
research support, non-u.s. gov't
Jul '13
Sleep, tiredness, and mental performance during simulated 4-on/8-off maritime watch shifts
cited by 31 papers
research support, non-u.s. gov't
Jul '13
How airline pilots adjust their body clocks during long flights between the USA and Asia
cited by 17 papers
research support, non-u.s. gov't
Aug '14
How sleep patterns and body clock timing relate to pilot fatigue safety measures
cited by 53 papers
research support, non-u.s. gov't
Nov '15
How repeated take-offs and landings cause fatigue in regional airline pilots
top 5% journal
cited by 49 papers
randomized controlled trial
May '08
How 6/6 and 4/8 Work Schedules Affect Sleepiness in Bridge Officers
cited by 64 papers
journal article
Nov '08
How Sleep Loss Affects the Performance of Anesthesia Trainees and Specialists
cited by 70 papers
research support, non-u.s. gov't
Dec '06
Physical effort, tiredness, and daytime sleepiness during two weeks of extended work hours at building-site camps
top 30% journal
cited by 20 papers
research support, non-u.s. gov't
Apr '16
Sleep Grogginess During a Simulated 6-Hour Work, 6-Hour Rest Shift Schedule
cited by 13 papers
journal article