Working nights and shifts is associated with substantial health risks. In the worst case, errors associated with lack of sleep or a heavy workload can lead to serious incidents.
“We’re not designed for nocturnal work, and night shifts or irregular working hours can undoubtedly have negative health effects,” says Bjørn Bjorvatn, professor of medicine at Haukeland University Hospital in Bergen.
Also director of the Norwegian competence centre for sleep disorders and the centre for sleep medicine at Haukeland, he participated in the “Good Night” webinar staged by the Petroleum Safety Authority Norway (PSA) in May 2021.
One risk is obvious, Bjorvatn notes. “Insufficient sleep makes you sleepy, so that you risk nodding off behind the wheel of your car, for example. That can have fatal consequences.”
A long series of studies have shown that poor sleep over time increases your risk of developing mental and physical problems. You could, for example, get anxious and depressed from sleeping poorly and too little.
Insufficient sleep over time has also been linked to weight gain, diabetes 2, cardiovascular diseases, increased risk of dementia, reduced fertility, cancer – particularly breast – and higher risk of death.
“This emphasises that sleep is essential for all life, and that reducing it below the amount you need can have long-term consequences,” Bjorvatn warns.
“The main rule when deciding what’s sufficient sleep is fairly simple: if you feel rested during the day, you’ve slept enough. That applies regardless of the number of hours you sleep. The great majority spend six-nine hours asleep.
“Sleep problems can fortunately be treated, and the crucial factor is getting enough sleep. So if you’re working nights and nevertheless sleeping well, you don’t need to be that worried.
“If, on the other hand, you don’t manage to sleep while on night work, the health risks have been clearly documented.”
But why are we so dependent on sleep? A popular theory is that it allows the brain to clean out junk accumulated while awake. If that process does not occur, we get problems with cognitive function and a greater risk of incurring a number of conditions – including dementia. A range of active processes also occur during sleep, including deleting growth hormones.
However, sleeping is also very important for learning and memory. In fact, we need to sleep well not only before learning something, but also the night after in order to remember what we have learnt.
Deep sleep is considered the most important for being rested. It occurs in the first three-four hours of sleep, regardless of the time you go to bed, and is important for transferring information from short-term memory to storage areas in the brain.
REM sleep is often called “dream sleep”, because virtually all our dreaming takes place in this phase. A lot of REM sleep is usual in the morning hours, and many people generally wake from it. This type of sleep is important for problem solving and creativity, and we need it to understand what we remember.
Light sleep appears to be important for forgetting or removing unnecessary memory components. You do not need, for example, to remember where you put your car keys yesterday – it is enough to recall where you put them today.
The various sleep stages play specialised roles for memory, so it is important to pass through all of them every night.
Source: Skiftarbeid og søvn (Shift work and sleep), Bjorvatn, 2019
Our circadian rhythm reaches its nadir at night, and most of us go to bed when the cycle is on its downward track. We become sleepier and sleepier until our low point is reached. This is when most of us find it most difficult to stay awake – and when the risk of making errors is at its highest.
“So it’s important when working at night to be particularly observant when you’re at your own nadir, and for colleagues to help each other through their most difficult period in order to avoid accidents,” observes Bjorvatn.
“You could talk with others, drink coffee or move around. Short catnaps are also very effective if you have the opportunity to take them.”
The normal routine for people is to sleep on their downward circadian cycle and wake up one-two hours after their own nadir, he explains. This means that those working nights who go to bed in the morning actually want to sleep when their rhythm is trying to keep them awake – a poor basis for good-quality rest.
“Those on a three-shift rotation accordingly do best to change clockwise. That’s easier because most of us have a circadian rhythm which is a bit longer than 24 hours. So a morning shift should be followed by an evening session and then by night duty, rather than the reverse order.”
Guide on night work
Working Together for Safety published a guide on night work in 2019, with specific advice to companies which need to make provision for working outside daytime hours.
Can threaten safety offshore
Insufficient sleep and disturbed sleeping rhythms not only impact health, but also increase the risk of errors. That can have serious consequences on an offshore facility and – in the worst case – cause a major accident.
“Performance, reactions and making decisions all get poorer at night,” comments principal engineer Elisabeth Vaagen in the PSA’s occupational health and safety discipline. “That increases the risk of making errors.
“Taken together with the negative health effects which we know night shifts can have, this means regulatory requirements for and curbs on such work in the petroleum sector are and must be restrictive.”
However, whole shifts at night are not the only source of concern for the supervisory authorities. Nocturnal call-outs are also regarded as night work, and making provision for sufficient rest between such sessions is important.
Overtime also shortens leisure periods and provides less time for sleep. An integrated view must therefore be taken of the length of the working day, the time of day and the number of days when assessing the risk of various forms of nocturnal work.
“We’re concerned to ensure that the companies organise work in such a way that the health of the individual is safeguarded and the risk of errors is minimised,” says Vaagen.
“In those case where night working is necessary and unavoidable, a number of risk-reducing measures are available.
“Working time and nocturnal work are risk factors which must be assessed and dealt with in the same way as other risks.”
Good advice for improving sleep after work
Take care of built-up sleep requirements
- Exercise regularly, but cease at least three hours before going to bed.
- Avoid sleeping during the day (you can take a catnap of less than 20 minutes).
- Do not remain in bed beyond your expected length of sleep.
Maintain a good circadian rhythm
- Get up at roughly the same time every time, including at weekends.
- Get at least 30 minutes of daylight every day.
- Avoid being exposed to bright light when waking up.
Reduce activities in the evening and during the night
- Avoid coffee, tea and other drinks containing caffeine at least six hours before bedtime.
- Avoid nicotine before bedtime and when waking up.
- Avoid using alcohol as a sleeping aid.
- Avoid strenuous exercise in the final hours before bedtime.
- Avoid being hungry or eating a heavy meal at bedtime.
- Avoid using the bedroom and bed as a workplace.
- Avoid using electronic media in bed after bedtime.
- Develop your own bedtime ritual.
- Ensure darkness and quiet in the bedroom. If necessary, use an eye mask and earplugs.
- Do not look at the clock if your sleep keeps being interrupted.
- Learn a stress-reducing technique, and use it when your sleep is interrupted.
- Allocate half-an-hour to “problem-solving” well ahead of bedtime.
- Take a hot bath a couple of hours before bedtime.
Source: Skiftarbeid og søvn (Shift work and sleep), Bjorvatn, 2019