How do I sleep well on night shifts?

You come home as everyone else is leaving, squinting into a bright morning, wired and worn out at once. The room is never quite dark, and by the time you wake the bins are going out and the school run is a couple of hours away. You've had four hours, and they felt like two. That sleep ran short because of the hour you lay down in¹1 Boivin et al., 2022. It wasn't you sleeping badly.

You get into bed after the shift, perhaps still wired from the ride home, at the hour your body clockbody clock The timekeeper in your brain that runs on a cycle of about a day, setting when you feel sleepy and when you feel alert. Daylight, especially in the morning, keeps it in step with the clock on the wall. begins its day. Two things decide when you sleep. One is sleep pressuresleep pressure The body’s need for sleep, which builds the longer we stay awake and eases while we sleep., which builds the longer you're awake and drains away while you sleep¹1 Boivin et al., 2022. The other is the body clock, which pushes for wakefulness at set times of day¹. When you first lie down, both point towards sleep, and it usually comes quickly¹.

A few hours in, the pressure has mostly drained. The clock, meanwhile, has been winding up all morning, and it's the clock that wakes you early¹. Why would it push harder just as you're trying to sleep? Its push to wake you rises through the day and doesn't peak until the evening¹, so every hour you stay in bed, it pushes a little harder. Once it has woken you, many night workers can't get back to sleep¹²2 Pilcher et al., 2000. In study after study of real night workers, sleep after a night on ends after four to six hours¹². That's the clock at work.

You can see the clock's share of this in a lab study. Healthy young men each spent ten hours in bed a day across five simulated work days, some with those hours at night and some in the day. Those whose ten hours fell at night slept 8.4 of them, while those whose ten hours fell in the day slept 6.4⁵5 Jackson et al., 2014, and the daytime sleepers were the sleepiest too. Two hours went missing in a lab bedroom with no bins, no doorbell and no school run. The hour of the day was the main thing left to explain it.

People differ, too. Natural night owls tend to cope with night work better than early birds¹1 Boivin et al., 2022. If a colleague sleeps longer after the same shift, that difference was there before either of you lay down.

Perhaps you've hoped that this run of nights, or the next, will be the one where your body finally gets used to it. For some people the clock shifts a little, though rarely all the way. Why is it so hard to move? Part of the answer is your own front door. The ordinary day at home keeps pulling the clock back, with its daylight, its errands and its family meals. Oil-rig workers, cut off from all of that, adapt far more¹1 Boivin et al., 2022. On a rig there's nothing to remind the clock what time the rest of the world keeps. At home, every school run and every lunch with the family does exactly that.

When researchers gathered six studies that measured the body clock directly in people on permanent nights, they set rigs and remote mines aside and looked at ordinary jobs. There, fewer than three in a hundred had a clock that had fully turned around, and fewer than one in four had shifted enough to benefit from it³3 Folkard, 2008. The length of a run matters as well. Most night workers show no real shift within three nights in a row¹. Runs of more than four or five nights move it further, by very different amounts from one person to the next.

People on permanent nights do report a little more sleep than people who rotate²2 Pilcher et al., 2000. That's often read as steady nights letting the clock adjust. The researcher who gathered the clock studies reads it another way: so few of those clocks had moved much that the longer sleep may come from greater sleep pressure³ instead.

What you can aim for is enough sleep around a clock that mostly stays where it is. One team reasons that a full flip isn't practical for most people anyway. The clock moves too slowly to swing back for days off⁶6 Smith et al., 2009, they point out, and no amount of light, caffeine or napping fully removes the low point in the small hours⁶.

It may help to go to bed soon after you get home and keep that hour steady from one day to the next: home, dark room, bed, at the same time each day, on the mornings your home allows it. Researchers who study this with young volunteers in the lab recommend a regular day sleep that starts early⁷7 Crowley et al., 2003, and in one of their studies people slept from 8:30am to 3:30pm after each night⁶6 Smith et al., 2009. They were aiming for a clock that turns all the way around. You can borrow the shape even when a full turn isn't your aim.

If that main sleep keeps ending at one or two in the afternoon, a second, shorter sleep later on can win back some of what the clock takes. In the same ten-hours-in-bed study, the men whose time was split into two five-hour blocks, 3am to 8am and 3pm to 8pm, slept 7.2 hours⁵5 Jackson et al., 2014, against 6.4 for one block in the day. Nobody works that exact timetable, and these were young men in a lab rather than people going home to jobs and families. Still, it suggests a main sleep plus a top-up can add to the total. For most night workers, the natural top-up is a nap before the next shift.

It's the afternoon before a shift. If it's the first of a run, the night ahead is usually the worst¹1 Boivin et al., 2022. Why that one? You've been up since the morning, so by the small hours you've been awake a long time just as your clock reaches its low point. In one study of fifty-four truck drivers, the odds of severe sleepiness were nine times higher on the first night shift¹ than on day or evening shifts. A nap breaks that stretch, and it's the step sleep doctors put first. They recommend a nap before or during the night shift⁴4 Morgenthaler et al., 2007 to keep you alert and working well, and they back it more firmly than bright light or caffeine⁴.

One team tried it with people who really do work night and rotating shifts. Before the first two of four night shifts, the workers took an evening nap and had caffeine. Then they went in, and on shift they performed better and were less sleepy⁸8 Schweitzer et al., 2006. Out in the field the nap and the coffee came as a pair, so that study can't tell you which did the work. In the lab, with volunteers on simulated nights, the nap and the caffeine each helped on their own, and worked best together⁸.

If your work lets you nap on shift, the studies placed it in the small hours, most often starting between 2am and 3am. Taken together, thirteen small studies found that naps of twenty to fifty minutes reduced sleepiness and sharpened reaction times through to the end of the shift⁹9 Ruggiero & Redeker, 2014. Naps of an hour or more sometimes left people groggy and slower straight afterwards⁹, in the fog called sleep inertiasleep inertia The groggy, slow feeling just after waking, before the brain is fully up to speed.. Are naps good for you? goes into how long a nap to take.

If your workplace has a brighter room or a better-lit corner, the night is the time to be in it. Sleep doctors recommend bright light at work during the night shift and limiting light in the morning⁴4 Morgenthaler et al., 2007 wherever you can. What does the light do for you? Mostly it keeps you sharp. It changes how alert you feel more reliably than it moves the clock⁴, which suits a night when the clock won't budge.

The ride home is the other half. In one lab study, sixty-seven young volunteers worked simulated night shifts with only room light, then wore sunglasses home. Darker sunglasses helped the clock shift towards day sleep more than ordinary ones did⁷7 Crowley et al., 2003, and the researchers suggest glasses as dark as possible on the commute⁷. A field study in police officers pointed the same way¹1 Boivin et al., 2022. If the morning sun meets you at the door as you leave, a pair kept in your work bag means the bright part of your day ends there, and the dark room at home keeps it that way.

How far can you trust the light? Researchers who looked only at randomised trials found them too small and varied to be sure that bright light or naps on shift help¹⁰10 Slanger et al., 2016. The sleep doctors' advice draws on more than those trials: lab simulations, field studies and expert judgement, a wider spread of work though a lower grade of evidence. Trials as small as these can't answer the question either way. A brighter corner costs you little if you'd like to see what it does for your nights.

You've probably tried the blackout blinds, the earplugs and the fan, and it helps to know what they can do and where they stop. A dark room shuts out the morning light that sleep doctors suggest limiting⁴4 Morgenthaler et al., 2007. Even so, the young men in the ten-hours-in-bed study, with no household around them at all, still slept short in the day⁵5 Jackson et al., 2014. The room can't override the clock. What it can do is protect the sleep the clock allows, and the things that do that are small and ordinary: the phone silenced, a note on the door or the doorbell switched off so deliveries don't wake you, and, where the household can manage it, an agreed stretch of the morning when the house goes still for you.

In a home with children to get to school and no one else to take them, that stretch may only be a couple of hours. It's a reasonable trade to put the main sleep wherever it's best protected, even if it starts later or comes in two pieces. You may still lie there hearing the kettle, the school bags and the front door as the house gets on with its morning without you.

Perhaps someone at home has told you, kindly or not, that you get to sleep all day. It can help them to hear that, for you, this is the night. A body asked to sleep in daylight gets less of it than they'd guess.

If you've tried melatoninmelatonin A hormone your brain releases as darkness falls, telling the rest of your body that night has come. It's also sold as a tablet. too, Is it okay to take melatonin every night? looks at it in its own right.

If there's a cup of coffee in your hand at 3am, it's probably doing you some good. In trials, caffeine tended to improve shift workers' attention and performance on shift⁴¹¹4 Morgenthaler et al., 200711 Ker et al., 2010, though most of them were small simulations in young people. With day sleep already short, the question that matters is how late in the shift to have your last cup, and How long does caffeine stay in your system? works that out. If a drink is how you come down after work, Does alcohol help you sleep? looks at what it does to the sleep that follows.

After a night shift the drive home is genuinely risky, and for many night workers the car is still the only way home. In a test-track study, sixteen night workers each drove for two hours on a closed track with a safety driver beside them, once after a night shift and once after a night's sleep. After the night shift, six of the sixteen drives had near-crashes and seven were stopped early for safety¹³13 Lee et al., 2016. After sleep there were none. Drowsiness showed within the first fifteen minutes, and every near-crash came after forty-five¹³. It was a small study, and the drivers stopped every quarter of an hour to answer questions, which may have kept them more alert than a real commute would.

The researchers advise night workers to keep the drive short or find other transport¹³. If someone offers you a lift, you could take it, especially after the first night of a run. When you're the one driving, a shorter route keeps you on the road for less time, though with drowsiness setting in so early, no length of drive in the study stayed clear of it. If your eyes start to close, please stop somewhere safe, and Can a nap help if I'm drowsy at the wheel? sets out what helps then.

If you've woken at two with the house already moving, that was your body clock ending the sleep¹1 Boivin et al., 2022, right on time. You could get up and eat, then lie down for a nap before you leave. On shift, there's bright light to look for where you can. On the way home, the dark glasses come out of your work bag. At home it's the dark room and the silenced phone. And tomorrow morning you could go to bed at the same hour, while the rest of the street heads off to work.