TAKE A REST, YOU DESERVED IT

The summer holidays are over and those of us on the mainland have returned to our desks with renewed vigour. Of course, the summer holidays helped us to be with our families, friends or, like one of my friends, at beach parties – to do the crazy thing we’ve been waiting to do all year. We are all different people during the summer holidays, and of course we need to rest and behave differently for a while. But a friend of mine got me thinking when he said: “Actually it would be great to be like a sailor – you work a bit (sailing) and then you come home and have a beach party every few months and the ship also comes into ports where you can have a “little beach party” again!

Of course, this friend of mine has never been on a ship and has only the most basic idea about the rest and fatigue of sailors. He comes home after work, eats lunch, lies down on the sofa and takes a nap, rests until tomorrow, and dreams of beach parties at night. And you, are you like that? Can you get rid of that tiredness in your guards?

Well, not really. Fatigue is the number one enemy of seafarers, one of the biggest problems of modern seafaring, for which no suitable antidote has yet been found.

But what exactly is fatigue? To a physiologist, fatigue is a decrease in muscle strength associated with the loss of muscle glycogen, dehydration and the accumulation of waste products such as lactic acid. For a psychologist, it is a mental state characterised by a decrease in motivation and an increased threshold for stimuli, as well as a decrease in the accuracy and speed of solving problems and psychomotor tasks. There are countless definitions, and this shows that we have not solved the problem.

One of the definitions is that fatigue is a state of sluggishness with reduced ability to perform activities, and it is based on a neurophysiological mechanism. In this context, neuromuscular fatigue is caused by an overload of the psychomotor system due to precise or repetitive work, such as navigating through dangerous passages or entering a harbour. There is also what is known as Chronic fatigue, which results from the accumulation of long-term fatigue effects and can be accompanied by physiological and psychosomatic disorders and behavioural changes.

So, there are both physical and psychological causes of fatigue, no matter how you define it, and on ships it is even caused by what we thought would alleviate it. Automation has led to a reduction in physical work on board, but also to a reduction in the number of crew members. Semi-automated and computerised technology, which is now present on all ships, places increasing demands on human mental capacity and leads to mental fatigue, a reversible disorder of behavioural stability that manifests itself in disturbances of perception, decision-making and memory, as well as various sensory-motor disorders. Numerous studies of maritime accidents show that they were caused by captain’s fatigue. One of my patients got off a ship in the Gulf of Mexico after only two months, even though he had an exceptional “American contract”. He said: I practically didn’t sleep except for a few hours a day, we were constantly “manoeuvring”. Yes, they don’t give good contracts to America just like that. But at least he was smart enough to stop before he hurt himself or the ship.

In addition to the intensity and duration of physical and mental effort, fatigue levels on board are affected by health problems and other characteristics of the workers, environmental factors, diet and circadian rhythms, which we will talk about in another text.

Fatigue is not only related to the type, duration and intensity of work, but also to the physical conditions and social climate in which the work is performed, as well as to worker characteristics such as gender, age, health, skill level, training and motivation. In everyday work, the main indicators of fatigue are a decrease in the quantity and quality of work, an increase in variability in the quality of work, the occurrence of spontaneous breaks and unnecessary movements (movements that are not essential to the work itself), difficulties in retrieving known information, and difficulty and slowness in understanding situations and decision-making. Some of these indicators of boating fatigue are extremely dangerous.

Fatigue can therefore also be defined as a reduction in the ability to maintain concentration and an associated reduction in the ability to think and act effectively. The Marine Safety Committee (MSC) considered the problem of fatigue on board ships at its 72nd session (May 2000) and established standards for the characteristics of fatigue and its causes on board ships in document MSC 72/15.

Fatigue reduces concentration and work efficiency, and its development seriously threatens the safety of the ship and the crew. In a seafarer, fatigue can be divided into two phases: the first is when the seafarer has a feeling of excessive exhaustion and reluctance to do what is necessary – for example, to perform a task on deck or to check the position. This is why the saying “it’s time to check the position when you think about it” was invented! When analysing maritime accidents, no other category of error occurs as frequently as navigational error due to fatigue!

Even sailing at sea causes fatigue more quickly than working on land, because all actions on board are performed in conditions of constant rocking / vibration of the ship and therefore require the participation of several muscle groups and therefore greater energy consumption. Even during sleep and rest in the cabin of a ship sailing in rough seas, or even when the ship is moored in rough seas, energy consumption is 10-30% higher than on land. Again, this is due to the need to stabilise the body in space using a greater number of muscles through compensatory body movements than during sleep.

Sailing conditions, such as poor environmental conditions in stormy weather, may require a seafarer to be present to carry out work tasks even after the end of his shift. The same can be caused by the need for intensive transport over short distances, a small crew or insufficiently competent assistants. A seafarer cannot simply hand over his shift to someone else and go to sleep if his presence is required after his shift!

These needs, caused by the unpredictability of navigation, delay rest and quickly lead to severe exhaustion, which represents a major psychophysical strain and endangers the health of the crew and the safety of navigation. This exhaustion and the uncontrolled urge to sleep come in waves and can lead to short periods of sleep during which it is impossible for the seafarer to distinguish between being awake and being asleep. At this stage, atypical emotional reactions, changes in personality and mood with uncontrollable laughing or crying may begin. Stress and fatigue begin to disrupt the basic functions of the brain, and the simplest tasks can only be performed with great effort and usually with errors. Complex tasks become virtually impossible. Most dangerously, the sensory information on which decisions are made becomes unreliable, illusions (wrong interpretations of what is seen or heard) or hallucinations (visual and auditory experiences of non-existent things) begin to occur. The first signs of fatigue can appear after only 5 hours of sleep deprivation! The biggest problem then is that the simplest monotonous tasks, such as looking at the horizon or a lighthouse, are usually overcome by sleep. Even for sleepy people, maintaining concentration during the day is no easy task, and a drop in concentration is already noticeable after four hours of work, with the biggest loss occurring after 20 minutes.

It is also well known that the efficiency of purely motor tasks, such as steering, follows a predictable pattern. It usually takes 5-10 minutes to get used to the helm, and all experienced helmsmen know that after about half an hour the ability to maintain course begins to decline, slower for the more experienced of course. About two hours at the helm is the limit in good conditions, otherwise the shift should be shorter. As seafarer fatigue is a factor that has a significant impact on navigational safety, large multi-centre studies have been conducted on seafarer fatigue and stress and their impact on seafarers’ vital capacity. In these studies, symptoms of adaptation fatigue and stress were observed in 60.2% of the seafarers observed. The symptoms of first- degree adaptation fatigue, were as follows: minimal neuro-somatic insufficiency, occasional neurotic reactions, non-pathological vegetative disorders, partial adaptability. The prognosis of this adaptation is debatable. The second degree of fatigue was characterised by slight neuro-somatic insufficiency, psycho-emotional tension with regular neurotic reaction, partially decompensated adaptability and risk for the prognosis of adaptation. The third degree of adaptation fatigue is nothing but neuro-vegetative stress with neuro-somatic insufficiency, vegetative dystonia, neurosis-like state, complete de-adaptation and poor prognosis. On the basis of the data obtained from research, the concept of the neuro-vegetative model and the general adaptation syndrome have been formulated. According to its first phase, the tensions and strains last up to two months from the start of sailing. In the second phase, the resistance phase, there is a reaction that lasts from three to six months, and in the third phase, exhaustion, after six months of sailing.

As various studies have undoubtedly shown that work in shipping, especially on ferries, is extremely psychologically demanding, an EU project was launched with the aim of establishing new criteria for fatigue on ships. This project examined objective indicators and parameters of sleep on ferries, both during the voyage and during rest periods at home. In general, working on ferries, in conditions very similar to those on our (former) high-speed trains on the Adriatic, was found to be very mentally demanding. The average sleep time on board was found to be only 6.7 hours, which, compared to the physiological requirement of 8-8.5 hours of sleep, shows a significant accumulation of the so-called sleep deficit. Almost all respondents had problems falling asleep and about 4/5 of them woke up twice or more. One in five woke up more than once or had significant sleep disturbances. Sleep quality corresponded significantly with the phases of shift work. About 53% of the respondents considered themselves rested, 37% only sometimes rested and 10% almost never rested. This level of feeling fresh and rested is crucial for safety at sea. In a Danish study investigating the impact of the two-shift system (4/8) used on most ships, it was found that about 30% of seafarers had what could be considered a normal sleep pattern and 8% had a sleep pattern that could not be considered sufficient for complete rest. They do not get a proper night’s sleep during the voyage and a large percentage, show reactions related to fatigue and stress that increase during their stay on board. The fatigue and stress reactions are of such intensity that they lead to a reduction in memory, concentration and general efficiency. This should be considered as a consequence of the working environment and their ability to work is reduced to the point of being a safety risk.

Seafarers inevitably suffer from the consequences of “long sleep”. Working on watch does not allow for sufficient rest periods to re-synchronise rhythms and compensate for “long sleeps”, as is possible for shift workers on land. The working hours of seafarers and the demands of work on board inevitably set clear limits on the possible time for sleeping and waking. For example, early morning watch work makes it impossible to get up later, and evening shift work makes it impossible to go to bed earlier, which is a common way of compensating for the so-called “long sleep” of shore workers. Due to the particular characteristics of working on a ship, where the presence of a large number of crew members is required for various needs, the total amount of time for sleeping within a 24-hour period is often reduced. Due to the necessity of working on board, it is impossible to consider the biologically necessary sleep duration of 7 to 8 hours and, above all, a good night’s sleep. In addition, the conditions of stay on board and the need to work continuously do not guarantee optimal conditions for rest. Seafarers do not even have the opportunity to develop adequate synchrony, which takes about 3 days, to adapt to an 8-hour shift change that allows sleeping time to be shifted 8 hours later. If an attempt were made to move the sleep period 8 hours earlier, it would take 6-7 days. 

Sailors cannot even rely on synchronicity when using the most powerful “zeitgebers”, such as light. Working at night on the command bridge does not allow the light to be switched on so that the eye can quickly adapt from observing the horizon to, for example, a radar screen or a map, so a sailor who has to get up in the night watch and take over duty simply does not have the opportunity to “move” the organism in the same way as night shift workers on land who can “start” the organism with the appropriate lighting. It has also been found that the speed of biorhythm de-synchronisation depends on the degree of neuroticism and age. Less stable personalities and older people are more susceptible to such de-synchronisation. This is of great importance on ships because of the stressful nature of the work, the neuroticism of seafarers due to lack of participation in normal social life, and the problems associated with old age, in which de-synchronisation occurs if a person is not exposed to such a way of working. Longer work in the night shift leads to a reduction in the range of rhythmic changes in body temperature as an indicator of psychophysical abilities. This reduction is not the same in all people and is greater in the elderly, in whom, as we have already said, there is less stability in the synchronisation of rhythms and there are also changes in sleep during the night and wakefulness during the day.

The main reason why such work should be considered difficult is that the general working capacity of the body is not the same throughout the 24-hour period, forcing seafarers to work at a time when their psychophysical capacity is 30% lower. The de-synchronisation of biological rhythms is a consequence of this type of work, which also reduces the seafarers’ working capacity and makes work more tiring even during the normally acceptable working hours (between 5 pm and 10 pm). Although the work performed by seafarers on shore would not be considered extremely difficult, the fact that it is performed repeatedly in frequent night shifts and in conditions of de-synchronisation of biological rhythms, and therefore of weaker psychophysical abilities even during the day, makes it very difficult and harmful to health. The decrease in psychophysical abilities is not only a great strain for the organism, but also results in the fact that the majority of accidents in navigation occur during night shifts, which naturally endangers the safety of navigation.

Shift work is less likely to be a direct cause of the disease, but today it is undoubtedly a significant risk factor, i.e. it sensitises the organism to the disease. In terms of biological rhythms, shift work on board is harmful because it disrupts them, particularly the basic wake-sleep biorhythm. In seafarers, this rhythm is constantly disturbed. One of the most important health consequences of night work in watchkeeping is a decrease in the body’s immune defences, which significantly endangers and damages the organism, both through a decrease in immunity to acute infectious agents and through a decrease in immunity to carcinogenic agents, with a long cumulative time for the development of diseases from which one becomes ill when one retires to a well-deserved retirement. Did you know that in the Nordic countries it is forbidden for women to work at night and that a higher incidence of breast cancer has been observed in those who have worked at night? Cardiovascular disorders are also aggravated by shift work because shift workers smoke more, using cigarettes as a stimulant for alertness, and are more likely to be obese, which are direct cardiovascular risk factors. The use of alcohol is also a way of facilitating falling asleep at an “unnatural” time of day, and this, together with other reasons, accounts for the increased alcohol consumption among seafarers. For this reason, alcoholism and smoking are not observed among seafarers as they are among land-based workers, since they are a consequence of the nature of the work and have the characteristics of “self-medication” and are occupational risk factors.

The first signs of intolerance to shift work may appear after one or two years of shift work, in others after 5 to 10 years, while there are a small number of people who can work shifts after the age of 45 without affecting their health and ability to work. Studies have shown that at least 20% of shore-based workers cannot adapt to shift work to the extent that they have to be transferred to non-shift work relatively soon after starting shift work for health reasons. While some seafarers solve their problem through their employer by being transferred to another workplace or quitting their job, for others the problem only becomes apparent after an accident at work or when the use of psychotropic drugs and alcohol or other health problems are discovered.

Tolerance to night work decreases after 45 years. This is one of the reasons why working on a ship in old age has a different effect on a worker than working a shift on land. It has also been proven that people with longer working experience are less tolerant of night work, where there is a cumulative effect of age and conditions (demands) at work. It is also known that people with so-called A-type personalities (more susceptible to coronary disease, one of the main causes of death among seafarers), who are more likely to choose a maritime profession because of their characteristics, find it more difficult to tolerate shift work. Even if the work is not dangerous to the worker’s health as such, the fact that these compensatory abilities decrease with age suggests that older age is contraindicated for working on board ships and that seafarers must have a shorter working life.

Neither in practice nor in modern science are there solid criteria for determining the degree of tolerance to shift work of each individual worker, so that despite psychological selection, seafarers enter the profession without the possibility of checking how they will adapt to such a way of working. It should be emphasised that there is no scientific proof that such adaptation is even possible. Only the consequences are known. This way of working is an extraordinary stress factor for physical and mental capacities. It has been proven that night shift work has a cumulative effect with the consequences of a higher morbidity rate.

We recover during the annual holidays, and this recovery is actually the body’s attempt to restore the balance disturbed by too much activity. During the 24-hour cycle, stressors and recovery must be balanced. Unfortunately, this is not possible due to the demands of navigation. Many of the problems and risks described above are present in other occupations, sometimes to a greater extent, but what makes seafaring different is the whole complex that the seafarer has to endure at once and which affects the whole voyage. Adapting to working conditions on board does not happen once in a lifetime. It lasts practically a seafarer’s entire professional life.

This will not change as long as ships operate 24 hours a day.

And how it works….You don’t have to live, but you have to sail.

Your Maritime Doc.