Shift work, poor sleep patterns, and ill health are related

Doctors have been worried for years that our 24/7 lifestyle culture could have unintended consequences for human health with more than four million people – 17 per cent of employees – in the UK now working shifts.

A research study done at the University of Surrey showed that night shifts triple the risk of heart disease while mental health problems, cancer, depression, diabetes, obesity and strokes have also been linked to poor sleeping habits including heavy bouts of snoring. Not surprisingly, this is called Shift work sleep disorder.

Shift work sleep disorder

Shift work sleep disorder is trouble sleeping because you work nights or rotating shifts. You also may have this problem if you have trouble staying awake or alert when you are supposed to be working your shift. You may not be able to sleep during the day, and you may not feel adequately rested with the sleep that you do get.

DJ at work in a club

Shift work sleep disorder involves a problem with your body’s 24-hour internal clock, or circadian rhythm. Light and dark help your body know when to be active and when to rest. Light is a cue to be awake, while dark tells your body to sleep. When you work at night and sleep during the day, your body’s internal clock needs to reset to let you sleep during the day. Sometimes that’s hard to do.

This sleep disorder usually is a problem for people who work all night. But people who work an early morning shift-for example, starting at 4 a.m. – also may have sleep problems. Rotating shift work also can be hard. In these shifts, people work the day shift on some days and the night shift on others or it can change each week.

Many people that work nights get plenty of restful sleep during the day. Some people are “night owls,” and they adjust well to working at night. So getting enough good sleep is not a problem for everyone who works nights.

The research into night shift sleep patterns

To assess the effect on the body of this disruption, researchers placed a panel of participants on a 28-hour day schedule without a natural light-dark cycle. As a result their sleep-wake cycle was delayed by four hours each day until they were sleeping 12 hours out of sync with a normal day. Blood samples showed that after this experiment the volunteers had a six-fold reduction in the number of genes that displayed a ‘circadian rhythm’ – a rhythm with an approximately 24 hour period.

All the participants were aged in their 20’s and the sleep study was carried out in very carefully controlled laboratory conditions. This research may help us understand the negative health outcomes associated with shift work, jet lag and other conditions in which the rhythms of our genes are disrupted and it may be very relevant for conditions in which our body clocks are altered such as in ageing.

The overall conclusions

The main findings were that shift work could damage almost 1,500 genes, explaining why it has been linked to such a wide range of health problems, and this disruption to the timing of sleep, also caused by jet lag, is feared to increase the risk of breast cancer, heart disease, diabetes and other life-threatening illnesses.

John Redfern