About 20 percent of shift workers suffer from sleep disorders caused by their work patterns, according to a new study by Helsinki University and the Finnish Institute of Occupational Health (TTL).
The research found that people with sleep disorders recover more slowly on their days off, and up to half can be constantly tired even in their free time.
Researcher Päivi Vanttola from TTL, who worked on the study, emphasised that it was important to nail down the causes of insomnia.
"Just like day workers, shift workers' insomnia and fatigue can be caused by an underlying illness, life situations or stress at work," Vanttola said.
Shift work prompts disorders
Vanttola's study found that many shift workers suffer from insomnia or chronic fatigue and if the issues persist, they can develop into Shift Work Sleep Disorder (SWSD).
The study also found that people with SWSD were less relaxed before bed, took longer to fall asleep and had a lower quality of sleep than those who did not have the disorder.
According to the study, working just three late or overnight shifts a month can contribute to constant fatigue, even outside of working hours.
Aorund one-in-five people in Finland have jobs requiring shift work and unusual working hours are becoming more common
In 2015 the European Working Conditions Survey found that 27 percent of women and 19 percent of men in Finland regularly carried out shift work
"Minimising the number of night and early morning shifts and providing sufficiently long recovery periods can alleviate the symptoms for many people with shift sleep disorders," Vanttola said.