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 hr on 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.


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.
Lützhöft
Margareta
M
Department of Shipping and Marine Technology, Chalmers University of Technology, Göteborg, Sweden. margareta.lutzhoft@chalmers.se <margareta.lutzhoft@chalmers.se>
Dahlgren
Anna
A
Kircher
Albert
A
Thorslund
Birgitta
B
Gillberg
Mats
M
D000328:Adult; D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012767:Ships; D012890:Sleep; D013548:Sweden; D013997:Time Factors; D014851:Wakefulness; D014940:Work Schedule Tolerance / Q000502:physiology*