Night Shift Lullaby

There are relatively few good songs about work, even though it’s a major part of most people’s lives. This song, by the Magnolia Electric Company, is one of them and probably sums up the experience of many shift workers. Shift work can make it difficult to socialise, affect personal relationships and seriously disrupt family life. Shift work can also have an effect on health.

The UK Health and Safety Executive point out that

Research has shown that shifts, particularly night and early morning shifts, can have undesirable consequences for workers including disruption of the internal body clock, sleeping difficulties and fatigue. These in turn can affect performance, increase the likelihood of errors and accidents at work and might affect health and well-being.

Longer term effects, which are more difficult to confirm, may include adverse pregnancy outcomes, coronary heart disease, gastrointestinal disturbances.

Recent research has also suggested that shift workers are at higher risk of developing cancer. In particular, there is evidence from four studies of a link between breast cancer and shift work for female workers. Although there remains some doubt about this link the evidence was strong enough for the International Agency for Research on Cancer to conclude that  “shift work that involves circadian disruption is probably carcinogenic to humans” in 2007.

The reason for a link may not appear to be obvious at first but it has been suggested that altered light exposure at night on levels of melatonin or other hormones may be responsible.

Whatever the possible cause, if shift work is associated with breast cancer in women it isn’t going to be easy to eliminate or control. The top of the hierarchy of control is elimination – removing workers from the exposure that causes the disease. But banning women from night shift work would be highly controversial. More work would be needed to understand the causative factors so that other approaches to control can be developed.

A paper in the British Medical Journal (BMJ) discussing the link between shift work and cancer reviewed current approaches to control

increase sleep duration, promote quick adaptation to night work, or improve subjective wellbeing at work. One possibility is to use our increasing understanding of the physiological control of the sleep-wake cycle to time our exposure to light and darkness for maximum adaptation. Using phototherapy lamps (especially those producing blue light, which is most efficient in resetting melatonin release time), wearing goggles, wearing sunglasses when driving home, and darkening bedrooms or wearing sleeping masks are being tried. Medications that are stimulants, hypnotics, or chronobiotics (substances that control the body clock) are also being

The association between shift work and cancer hasn’t been proven conclusively yet. More work is needed. But, in any case further work is needed to develop appropriate control strategies to mitigate the known  and probable effects of shift work on health.

Further Reading

HSE guidance on shiftwork

HSE Research Report on shiftwork and breast cancer

IARC Monographs Volume 98

Shift work and cancer (BMJ 2009;339:b2653)

Long-term night shifts can “double” breast cancer risk