Killer Night Shifts

We’ve all been there. The 7 p.m. alarm goes off and you’re up (after a few more presses of the snooze button), and on your way to another night shift. They say that the first night isn’t so bad, but come the third of four and you feel like you might need a personal referral to palliative care. Are you being melodramatic though? Or could there be some truth in the feeling that night shifts could be hastening your end? is here to find out.

Some good folks sponsored by the Karolinska Insitute in Sweden have done all the hard work for us and conducted a meta-analysis of various papers into the effect of shift work on sleep and health. As you might expect, most of the studies show that night shifts are associated with shorter duration of sleep (both reported and substantiated with polysomnography studies). Quickly rotating shift work schedules, as has become the fashion as hospitals try and bend rotas to fit the European Working Time Directive and Jeremy Hunt’s latest stroke of brilliance, also correlate with shorter duration sleep. So those nightmare days of seven night shifts in a row may actually be better for us (well, allow us to get more sleep at least).

How come it doesn’t feel like that though? By the fifth of seven night shifts, am I the only one who feels like a zombie from the Walking Dead? Apparently not. Kecklund and Axelsson’s (just take a moment to enjoy those wonderfully Swedish names) review shows that shift workers frequently report symptoms of excessive sleepiness and one study of Norwegian nurses (n=1968) showed the ones who worked more night shifts were more likely to develop chronic sleep/wake problems i.e. shift work sleep disorder.

So now that you’ve been vindicated in feeling so ghastly on nights, here comes the killer (quite literally) question – are nights negatively affecting your health?

The answer is, most likely, yes.

As the news headlines suggest, there are links between shift work and increased risk of developing a number of different health conditions including Type 2 Diabetes. This is confirmed in the meta-analysis. Various researchers propose certain mechanisms as to why this might be, but the definitive causal mechanism has not yet been elucidated. Furthermore, although the shift work is connected to less sleep, we are still uncertain as to how a lack of sleep may be connected with such health conditions as Type 2 diabetes and the risk of developing obesity. This is unsurprising given how relatively little we know about sleep.

So the answer, as always, is more research. More investigation as to why and how shift work and sleep deprivation ties into the development of these health conditions, because when we know the mechanisms, we can intervene for the good of all shift workers, not least our medical staff.

Maybe then we can all sleep a little easier.


“Health consequences of shift work and insufficient sleep” by Goran Kecklund and John Axelsson (BMJ 2016;355:i5210)

“Shift Work Disorder in Nurses – Assessment, Prevalence and Related Health Problems” by Elisabeth Flo et al. Public Library of Science One 2012; 7(4): e33981

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