By Hugo Novais, biotechnologist, former pro swimmer, CrossFit coach and a rotating 12-hour shift worker myself.
It's 4 p.m. on the day of your first night shift. You've been up since 6 a.m., and in three hours you start a 12-hour shift. Most people just push through and rely on coffee. But one of the best-studied tools for night work is much simpler: a planned nap before you leave home. Here's what the research says about when to take it, how long it should be, and how to avoid waking up feeling worse.
Why the first night is the hardest
Your body clock doesn't flip with your roster. A detailed review of shift-work research found that even after several nights in a row, most people's clocks have barely moved towards a night schedule (Boivin et al., 2022). On the first night of a block there's a double problem: your clock is still on days, and you've often been awake since the morning. By 4 a.m. you can be close to 22 hours awake, at the low point of your body clock's day.
A nap before the shift doesn't fix your clock. What it does is clear some of the sleep pressure you've built up, so you start the night with less to fight against.
What the studies found
Before the shift. In a set of lab and real-workplace studies, an evening nap before night shifts, combined with caffeine during the shift, improved alertness and performance more than either one alone, in the lab and in real night workers (Schweitzer et al., 2006). The nap alone helped too; the combination helped most.
During the shift. A systematic review of 13 studies of naps taken during night shifts found that, despite a short period of grogginess immediately afterwards, night-shift naps generally reduced sleepiness and improved performance (Ruggiero & Redeker, 2014). In one study of 12-hour shift workers, a single 20-minute nap during the first night shift improved reaction speed on a vigilance test at the end of that shift, although it made no difference on the second night (Purnell et al., 2002).
It's worth being honest about the quality of the evidence: a Cochrane review concluded that the research on naps for shift workers is promising but still low quality, and that better trials are needed (Slanger et al., 2016). Even so, a nap is cheap, low risk and easy to test on your own roster.
How long should the nap be?
There are two good options, and one bad one.
- 20–30 minutes: a quick top-up. You're less likely to wake from deep sleep, so the grogginess is shorter. Good before a second or third night, or when you only have a short window.
- About 90 minutes: more real sleep, which is useful before the first night of a block when you've been up since morning. Allow time to wake up properly before you drive.
- Somewhere around 45–60 minutes: the awkward middle. You're more likely to wake from deep sleep and feel foggy, without the benefit of a full cycle.
Finish the nap at least an hour before you leave for work. That gives you time to shake off the fog, eat your pre-shift meal and get some bright light.
The fog after waking (and why it matters for driving)
That heavy, slow feeling just after a nap is called sleep inertia. A review of the research found it can affect thinking and reaction time for a period after waking, and that it's worse when you're sleep-deprived or waking at a bad time of your body clock's day (Hilditch & McHill, 2019). For shift workers, both are often true.
So two simple rules: after an on-shift nap, allow about 15 minutes before safety-critical work. And after any nap, don't get behind the wheel until you feel properly awake. In a US study of night-shift workers on a closed test track, 37.5% of drives after a night shift had a near-crash event, compared with none after a normal night's sleep (Lee et al., 2016). If you're fighting to keep your eyes open, don't drive.
How I set it up on a 7 p.m. start
- First night of a block: sleep in as long as I can in the morning, then nap from about 2:30 to 4 p.m. in a dark, cool room.
- Second night: a 25-minute nap at about 5 p.m., after my main day-sleep.
- On shift: if a planned break allows it, 15–20 minutes in the early hours, then 15 minutes to wake up before going back to work.
- Days off: naps under 30 minutes and before mid-afternoon, so they don't steal sleep from the night.
What to do this week
- Put a pre-shift nap in your calendar before your next first night, with an alarm.
- Pick your length: 20–30 minutes or about 90 minutes. Avoid the middle.
- If your workplace has planned breaks on nights, ask whether a short nap can be part of them.
The full plan
Napping is one of five "dials" I use on my own roster: Dark, Bright, Anchor, Nap and Fuel. I've put the whole system, with a 30-minute set-up for day-sleep, five roster templates and a 28-day plan, into a short book: The Shift Worker's Sleep Reset, Book 3 of my BioFit Blueprint Series. It's coming to Amazon Kindle shortly; search "The Shift Worker's Sleep Reset Hugo Novais".
And if you'd like your sleep, meals and training planned around your roster, that's what the BioType Nutrition Blueprint and BioFit Coaching are for. Book a consultation here.
This article is general education, not medical advice. If you have ongoing sleep problems, loud snoring, or you're falling asleep at work or while driving, see your GP.
