More than half the people working regular night shifts develop at least one sleep disorder.

This is particularly the case for young adults with a lower education.

These are the main findings of a large Netherlands study that investigated the relationship between different shift-working patterns, sociodemographic factors, and sleep disorders.

In Australia,16 per cent of all employees – 1.4 million people – have shift work as their main job.

If the study results are translatable to the Australian setting, this would mean that more than 700,000 shift workers, including many of our health workers, are suffering with a sleep disorder. That would hardly be a surprise.

According to Monash University, rotating shifts, where schedules vary from week to week, are the most common form for women and men. Rotating shifts tend to have the most impact on one’s health, and are the most disruptive to one’s circadian clock.

More about the study

According to a statement from the GGZ Drenthe’s Mental Health Institute, Netherlands, more than 37,000 participants provided demographic information, indicating their shift-work patterns.

They also completed a questionnaire screening for six common sleep disorder categories:

• Insomnia
• Hypersomnia (excessive sleepiness)
• Parasomnia (abnormal and unnatural movements, behaviours, emotions, perceptions and dreams that occur while falling asleep)
• Sleep-related breathing disorders
• Sleep-related movement disorders
• And circadian rhythm sleep-wake disorders.

The results

Working regular night shifts was the most debilitating condition concerning sleep.

Half of the night-shift workers were found “to sleep less than six hours within 24 hours, 51 per cent reported one sleep disorder, and 26 per cent reported two or more sleep disorders”.

Digging deeper, the study revealed that males slept fewer hours than females, but that sleep disorders were more common in women.

Age also influenced sleep health.

Older participants tended to sleep shorter hours, “but most sleep disorders and their comorbidities were found to be more prevalent among the youngest participant group, aged 30 and below”.

The effects of shift work on sleep were most prominent in young adults with lower levels of education. This group slept shorter hours “and had a significantly higher prevalence of sleep disorders and comorbidities thereof”.

Eating more, greater risks of heart disease

In March, Monash University published research that found “rotating-shift workers eat more kilojoules, snack more on junk food and don’t eat as many nutritious foods, increasing their risk of diet-related illness”.

Rotating-shift workers ate on average 264 more kilojoules than regular day workers. An increase of just 100 kilojoules each day can lead to a .5 kilogram weight gain over a year.

Shift workers also reported unhealthier dietary patterns than day workers, including irregular meals, more snacking or eating at night, less core-food consumption and more eating of discretionary foods.

Previous studies have found that “while shift work may be more convenient or pay more, it puts workers at increased risk of chronic illnesses such as cardiovascular disease and diabetes”.