Fatigue at sea in swedish shipping-a field study

Background Today many merchant ships sail with only two nautical officers, working a shift schedule of 6 hron and 6 hr off. There are concerns that such a shift schedule is related to fatigue. However, little data exist from onboard studies of seafarers. Methods Data were collected on board 13 ships. Fifteen participants worked on a 6-on, 6-off watch system and another 15 on a 4-on, 8-off watch system. Electrooculography, actigraphy, diaries, and reaction time tests were used to measure the effects of shift system on fatigue and sleep. Results and Conclusions Sleepiness was higher during the night shift in the 6-on, 6-off system. Moreover, sleepiness increased more during the watch in the 6-on, 6-off system compared to the 4-on, 8-off system. There was a trend toward shorter sleep episodes in the 6-on, 6-off system and sleep was more often split into two episodes. © 2010 Wiley-Liss, Inc.