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Sleep deprivation is not a major problem on ships with a three-watch system. However, motivation decreases during long watches and may affect the social environment on board. This is described in the final report from the extensive research project called Martha.

Tiredness and fatigue among crews on board three-watch ships on European and deep sea voyages have been examined in the Martha project. There was no widespread problem with lack of sleep among the 973 officers and crew who participated in the survey.

”Those who got too little sleep one day could usually catch up rather quickly, often the following day,” says Wessel van Leeuwen from the Stress Research Institute at Stockholm University, who took part in the project.
On the other hand, the researchers noted other effects on the seafarers in the form of fatigue. Fatigue describes the condition that occurs after a long period of tiredness, hard work and/or social problems. Those affected by fatigue have an increased risk of a number of health problems, including insomnia, sleep apnoea and infections.

Social isolation
The symptoms of fatigue are noticeable in different ways, including low motivation. Researchers in the Martha Study saw clear signs of this among participants. 

”People live in a socially isolated environment on board. It is rarely a problem for the first few weeks, but in time it may become increasingly difficult to work together. You perhaps have less patience with a colleague who has had a bad day, and conflicts arise more easily,” says Wessel van Leeuwen. When social life is affected, things which were not previously a problem can become a breeding ground for conflicts.

”Disagreements can easily arise between different groups on board. A lack of motivation could also affect work on board, so people don’t want to do more than what is absolutely necessary, but we haven’t looked into that in the Martha study,” says Wessel van Leeuwen.

Vessels from four shipping companies, two European and two Chinese, took part in the study. The crews were on board for between three and six months. Participants filled in a form every week with questions about tiredness, well-being and the quality of social life on board. At the start of the study period many people, particularly officers, said they thought they would be more tired towards the end of the voyage than when they signed on, but in fact this was not
the case.

”That is in line with results from other studies, which indicate that tiredness does not accumulate over time. If people sleep less than usual or work harder, the body tends to compensate through more deep sleep. However, there is a lower limit. If people get less than five hours of sleep, the shortage of sleep accumulates already after one or two days,” says Wessel van Leeuwen.

Those who are on board for very long periods experience problems with tiredness after a while. After 25 weeks there is a marked increase in the number of seafarers who feel tired and start to find it difficult to stay awake during working hours.

”The environment on board can be difficult in the long run, and stress and conflicts also affect how people sleep,” says Wessel van Leeuwen.

The fact that many seafarers feel exhausted when they come home and need time to recover is more to do with social pressures than long-term sleep deprivation, Wessel van Leeuwen claims.

”A lot of it is about changing and adapting. When you come home and it’s calm and peaceful, you relax and feel tired. It’s like the first few days of holiday for employees ashore. High levels of tiredness have been observed in earlier studies on ships with two-watch systems and coastal shipping with frequent port calls.

”Lack of sleep can be a major problem
on ships with two-watch systems, while those who work three watches and for longer periods tend to have other symptoms, such as less motivation. Motivation is something we plan to look into more closely in future studies,” says Wessel van Leeuwen.

A strange fact that surprised researchers in the Martha project was the large number of seamen who said they were morning people.

”Among Swedish people as a whole, there are far fewer who say they are morning people than the participants in our study. Whether this is linked to the watch system applied on board or something else, we just don’t know,” says Wessel van Leeuwen.
The results from the Martha study were discussed at the end of January in the IMO (International Maritime Organization).

About sleep
We spend about almost one third of our lives asleep. When we are asleep, normal thought processes shut down and a large proportion of brain cells undergo recovery and ”reset” our physical and mental balance. Most people need about seven hours’ sleep each night, although there are variations. Shortage of sleep leads to an increased risk of a number of illnesses, including infectious diseases, type two diabetes and cardiovascular problems. Sleep deprivation is also related to mental ill-health such as burn-out and depression.

Linda Sundgren


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