Sleep, Sleepiness, and Neurobehavioral Performance While on Watch in a Simulated 4 Hours on/8 Hours off Maritime Watch System

Documented as a direct or contributing factor in many maritime accidents, seafarer sleepiness jeopardizes safety at sea. Sleep, sleepiness, and neurobehavioral performance in a simulated 4 hours on/8 hours off watch system are investigated in this study, as well as the effects of a single free watch disturbance, simulating a condition of overtime work, resulting in 16 h of work in a row and a missed sleep opportunity. Thirty bridge officers (age 30 ± 6 yrs; 29 men) participated in bridge simulator trials on an identical 1-wk voyage in the North Sea and English Channel. The three watch teams started respectively with the 00–04, the 04–08, and the 08–12 watches. Their sleepiness was rated by participants every hour (Karolinska Sleepiness Scale [KSS]) and a 5-min psychomotor vigilance test (PVT) was carried out at the start and end of every watch. During 6 watches polysomnography (PSG) was recorded in the first and the second half of the week. KSS was higher during the first (mean ± SD: 4.0 ± 0.2) compared with the second (3.3 ± 0.2) watch of the day (p < 0.001). In addition, it increased with hours on watch (p < 0.001), peaking at the end of watch (4.1 ± 0.2). The free watch disturbance increased KSS profoundly (p < 0.001): from 4.2 ± 0.2 to 6.5 ± 0.3. PVT reaction times were slower during the first (290 ± 6 ms) compared with the second (280 ± 6 ms) watch of the day (p < 0.001) as well as at the end of the watch (289 ± 6 ms) compared with the start (281 ± 6 ms; p = 0.001). The free watch disturbance increased reaction times (p < 0.001) from 283 ± 5 to 306 ± 7 ms. For PVT lapses similar effects were observed. During at least one of the PSG watches one third of all participants slept. In the team working 00–04, sleep on watch was most abundant, and it increased following the free watch disturbance. It was revealed in this study that—within a 4 h on/8 h off shift system—subjective and objective sleepiness peak during the night and early morning watches. This coincides with a time frame in which relatively many maritime accidents occur. In addition, it was shown that sleepiness is strongly increased by overtime work. Finally, the amount of participants who fell asleep while on duty was striking.

• Record URL:
  https://doi.org/doi:10.3109/07420528.2013.800874
• Record URL:
  http://informahealthcare.com/doi/abs/10.3109/07420528.2013.800874
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/07420528
• Authors:
  • van Leeuwen, Wessel M A
  • Kircher, Albert
  • Dahlgren, Anna
  • Lutzhoft, Margareta
  • Barnett, Mike
  • Kecklund, Goran
  • Akerstedt, Torbjorn
• Publication Date: 2013-11

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 1108-1115
• Serial:
  • Chronobiology International
  • Volume: 30
  • Issue Number: 9
  • Publisher: Informa Professional
  • ISSN: 0742-0528
  • EISSN: 1525-6073

Subject/Index Terms

• TRT Terms: Drowsiness; Fatigue (Physiological condition); Maritime safety; Shifts; Ship simulators; Sleep; Vigilance; Watchkeeping
• Uncontrolled Terms: Polysomnography; Psychomotor vigilance task
• Subject Areas: Marine Transportation; Safety and Human Factors; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 01506204
• Record Type: Publication
• Files: TRIS
• Created Date: Jan 30 2014 1:16PM