What the night shift costs

The costs have come up one at a time. Here they are together. Much of this chapter is my own reckoning, apart from the places where I name a study.

Sleep. This is the obvious one. A waking that might have lasted ten minutes lasts two hours. If that happens three nights a week, you're losing something like five or six hours of sleep a week, every week. Those figures are an illustration, and yours will differ.

The next day. Cara Palmer and colleagues pooled more than fifty years of experiments on sleep loss and emotion, 154 studies in all. After lost sleep, people reliably felt less positive emotion and more anxiety. The day after a night shift you're flatter, more on edge and less patient. The problems you lay awake over now have to be faced by a less capable version of you. If the problem involved a difficult conversation or a careful decision, you've made it harder. The night shift claimed to be helping with your problems, and it has left you less able to deal with them.

Bad decisions. Occasionally a verdict from the night survives into the day and gets acted on. People send a resignation email at five in the morning, or a furious message to a relative. People cancel a holiday in a panic. Tubbs and colleagues, in the review from chapter 4, make the point that the night is when impulses are least well held in check. Most night verdicts dissolve by breakfast, fortunately. The ones you act on before breakfast don't get that chance.

The bed itself. If you spend many hours awake and agitated in bed, your body starts to associate the bed with being awake and agitated. Espie's paper calls this conditioned arousal and lists it among the long-recognised features of persistent insomnia. You may have noticed that you can doze off on the sofa at nine and then be wide awake the moment you get into bed. For most people, bed is a cue for sleep. If you've done enough night shifts in it, it becomes a cue for the shift.

Dread of the night. After enough bad nights you begin to fear them in advance. You go to bed wondering whether you'll wake, and braced for it. That puts you on the alert, and being on the alert makes a waking more likely and an easy return to sleep less so.

Your view of your own life. I think this is the least noticed cost. If several times a week you spend two hours being shown the worst version of your finances, your family and your prospects, some of it sticks. You can come to believe, in a general way, that your life is precarious and that you're barely coping. The belief comes from a view you're only ever shown at an hour when your judgment is at its worst. People who stop the night shift often say, a few months later, that their problems seem to have got smaller. The problems are usually much the same as before. What's changed is that they're no longer spending two hours, several times a week, looking at the worst version of them.

The person next to you. If you share a bed, your restlessness, your sighing and your trips to the bathroom cost someone else sleep as well. Your mood the next day lands on them too.

Set against all this is what the night shift provides. It gives you a feeling of being responsible, which lasts as long as the shift does. It gives you verdicts that are mostly wrong. It doesn't produce any actions.

You've been paying these costs for a long time without anyone setting them out. Once you see them together, I think it's plain that the habit isn't worth keeping.