Examined the Sleep Patterns of Commercial Pilots Working Different Shifts

Among those who received their graduation diplomas from the University of Iceland on Friday, February 20, was Sara Vöggsdóttir, who completed her master’s in health sciences. For her master’s thesis, she examined sleep and sleepiness among commercial pilots across different flight shifts, as well as the interplay between exercise and sleep. This is the first study of its kind conducted in Iceland.

Sara has been interested in sleep for a long time; sleep was also the focus of her final thesis for her bachelor’s degree in sports science at Reykjavík University, in which she compared two different assessment tools used to evaluate sleep. She got the idea for her master’s final project at the University of Iceland while working in Icelandair's training department. While there, she was asked to give a lecture on sleep for the airline’s pilots, who, like pilots elsewhere in the world, work shifts and fly at all hours of the day. “The pilots were aware of the impact that irregular working hours can have on their sleep but lacked strategies to tackle it,” Sara explains.

As a sports scientist, Sara thought exercise could be a good countermeasure to the effects of irregular sleep and says many studies indicate it improves sleep. At the same time, she became interested in researching the effects of shift work on sleep and sleepiness, Icelandic commercial pilots’ performance working different shifts, and whether physical activity might have a protective effect on their sleep. “I wanted to give them better advice or find out if this could be useful,” Sara says about the aim of the study

The First Study of Its Kind

In total, 50 pilots from Icelandair participated in Sara’s study, which examined sleep duration, sleep efficiency, time to fall asleep, frequency of awakenings during sleep, and duration of wakefulness. In short, sleep duration and sleep quality. She looked at 7 different flight shifts: early morning, morning, afternoon, late afternoon, night, and late night, with a layover in North America. This is, at least to Sara’s knowledge, the first time in Iceland that pilots’ sleep and sleepiness have been examined in relation to different shift schedules and with consideration given to physical exercise. “I wanted to try and examine the entire 24-hour cycle, so I had the duty roster of every single pilot who participated in order to be able to look at each individual’s full day,” she explains.

She examined their sleep either before or after the shifts. “How they slept before early morning flights, morning flights and afternoon flights, and how they slept after flying at night, but also how they slept during layovers,” she says.

She also looked at the difference in recuperative sleep after different night shifts. “On the one hand, pilots are going to sleep after a flight at around 8 a.m., which is still within a reasonably acceptable time according to the body clock, and on the other hand, at around 10:30 a.m., when it becomes more difficult to fall asleep and it also has greater consequences for the following night. I wanted to examine the quality of these naps,” Sara explains.

To assess sleep quality, the pilots wore a sleep and activity monitor during the study, which also measured the group's physical activity. “The monitoring lasted for two weeks for each pilot, ensuring that each individual was working different shifts during that period,” Sara says, adding that the pilots also kept a sleep diary.

Additionally, the pilots were asked to subjectively rate their sleepiness on different flight shifts using a specific sleepiness scale developed at the Karolinska Institute in Sweden, which has been used in other comparable sleep studies.

Sleep Significantly Shorter among Pilots on Early Morning Flights

It emerged that there was a difference in sleep duration across shift types among the pilots, with sleep significantly shorter during early-morning flights than during other shifts. Further, sleep during layovers in the US was significantly worse, i.e., of lower quality. “And that indicated that sleep quality during layovers was considerably less than on other nights, which isn’t good because after sleeping poorly like that, pilots go straight to flying at night, and that impacts both the pilot’s experience and his performance,” Sara says.

This was clearly evident in the pilots’ subjective assessment reports of their sleepiness. “In many instances, they scored high in sleepiness,” Sara points out and continues: “If it were possible to find ways to improve their sleep during layovers, then we could possibly minimise sleepiness during these flights.

The More Physical Activity, the Shorter the Sleep Duration

When it came to assessing the impact of pilots’ physical activity on their sleep, Sara says the results were interesting. “There was a significant correlation between physical exercise and overall sleep duration, but not in the direction we thought. The more physical activity, the shorter the sleep duration, and the more the pilots exercised, the longer it took to fall asleep,” Sara says and points out that, in general, research has shown that those who exercise regularly have longer total sleep duration and fall asleep more quickly.

Sara points out that the majority of participants, or nearly 90%, specified that they did exercise regularly, which is an influencing factor in the results. “It would be interesting and important to conduct another study where the proportion of those who are physically active to those who are not is more balanced, and possibly include an intervention where physical activity is controlled. We’d also need to look further into timing and intensity of exercise in this context,” Sara explains.

A Properly Planned Pilot Duty Roster is Crucial

Asked what conclusions could be drawn from the results, Sara says it is crucial that pilots’ duty rosters are properly planned. “Ensuring that people get a good rest in between flights to prevent cumulative fatigue, which could evolve into chronic fatigue, as that’s a risk factor when it comes to flight safety. That’s what airlines, regulations and the flight community are trying to ensure: that pilots won’t enter that state,” she points out.

If duty rosters are structured in such a way that people feel tired all the time, then they need to be changed. “For example, not always having the same people on early morning flights and late night flights. Try to manage the rotations a bit and consider the body clock in this context,’ she says.”

Sara’s supervisors were Yrsa Bergmann Sveinsdóttir, Professor of neurophysiology in the Faculty of Nursing and Midwifery at UI, and Erlingur Jóhannson, Professor of sport and health sciences in the university’s School of Education.

Examining Physical and Mental Performance of Icelandic Coast Guard Personnel

Sara has moved again across Reykjavík Airport for a doctoral degree at Reykjavík University. Pilots also play a role in her doctoral research, although they’re flying a different kind of vehicle this time. “This is a collaborative project between the Icelandic Coast Guard with the aim of trying to maximise the performance of Icelandic Coast Guard personnel, both physically and mentally. For this project, I have a team of experienced experts for support, like Hafrún Kristjánsdóttir, Hugh Fullager and Christopher Curtis,” she says about her doctoral project.

According to Sara, the first step is to analyse all the job roles, and she’s working on that now. “If we only take a winchman, what does his role involve? What are the main projects? What are the main challenges, both physically and mentally?” Sara says, adding that sleep will undoubtedly play a role in that study, since it is a major factor in health and performance. “This will be my project for at least the next three years, and hopefully we can contribute something toward even better health and performance in the Coast Guard.”