How to sleep on call: the waiting, the wake-up and the morning after

On-call work means being available outside your rostered hours, at home or on site, for a call that may or may not come. Doctors, nurses, firefighters, engineers, IT staff and utility crews all do it. The studies below look at people on call overnight; some measured real call-outs, others only the possibility of one.

What does the research say about sleep on call?

Two findings run through the list. Sleep on call is worse even when the phone stays quiet, and the moments after a call wakes you are a risk of their own.

Why does being on call cost sleep even when nobody calls?

The engineers in the 1988 study slept worse before any alarm had sounded, and the authors attributed it to apprehension about being woken. The Australian survey asked on-call workers what they turned over in their heads. The top answers were interruptions to family and leisure time (70%), missing a call (69%), planning in case of a call (69%) and not being able to make plans (67%).

Not every study finds the worry in the sleep itself. In two lab studies from the same Australian group (Sprajcer et al., 2018 and Kovac et al.), telling young men they would face a stressful task rather than an easy one if woken made no difference to how they slept. A lab bedroom with nothing real at stake is not the same as a pager on the bedside table, though, and the field studies and surveys fairly consistently find real on-call nights shorter and lighter.

The survey doesn’t test fixes, but its list suggests where to start. If the worry is missing the call, make that close to impossible: one alert you have tested at full volume, and Do Not Disturb set so only the call-out number gets through. If it’s the planning, do it before bed. Clothes, keys, bag and charger in one place leave nothing to rehearse in the dark.

What is sleep inertia, and how long does it last?

Sleep inertia is the grogginess and slowed thinking right after waking. A 2019 review by Hilditch and McHill sets out its shape:

• It is worst in the first 15 to 30 minutes and then fades, but full recovery can take an hour or more.
• It is worse after sleep loss, and worse when you wake near the low point of your body clock in the early hours of the morning.
• Right after waking, the impairment can match or exceed that seen after up to 40 hours without sleep.
• Naps of 30 minutes or less are less likely to cause it, though not immune.

That is the on-call problem in a few lines. A call that wakes you at 3 a.m. after a short night lands on close to the worst version of inertia there is. Where you can, put the minutes it takes to dress and get moving before anything that needs judgement, and check the first decision twice.

Can caffeine or light shake off sleep inertia?

The same review rates the countermeasures. Caffeine taken just before a short nap of about 20 minutes has the best support, because it starts working around the time you wake. Caffeine gum after waking shortened inertia but didn’t help the worst first stretch. Bright light, sound and cooling have weak or early evidence, and no reactive fix has clear, immediate benefit.

The caffeine nap has a well-known study behind it. In Reyner and Horne’s 1997 driving-simulator study, sleepy drivers given 200 mg of caffeine plus a nap of under 15 minutes had 9% as many driving incidents as on placebo, against 34% with caffeine alone.

On call, caffeine has a cost it doesn’t have on a normal shift: you may want to go back to sleep. A 2022 review on switching on for a call and switching off after it points out that whatever wakes you up for a call may also keep you from falling asleep afterwards, and that this hasn’t been studied well yet. Caffeine’s half-life is about 5 to 6 hours (the night-shift guide does the arithmetic), so a coffee at 2 a.m. for a twenty-minute call is still mostly in you at 6. It makes sense to save it for calls that will keep you up, or for the drive.

How should you nap when you’re on call?

When your sleep might be broken at any moment, sleep you get before the call is worth more than sleep you plan to get after it. That makes short naps the main tool. If you might have to act straight away on waking, Hilditch and McHill suggest keeping naps under 30 minutes. NIOSH’s shift-work course adds that waking after about 20 or about 90 minutes tends to leave you less groggy than waking after about an hour.

A 2025 review of fatigue guidance for on-call workers went through 65 guidance documents from regulators and 17 studies of what works. It found very little research outside limits on working hours. Training, education and call management, such as protected naps during on-call periods, were among the few measures with some supporting evidence.

What should you do after a night of calls?

Treat it like the morning after a night shift, because for your body it was one. The drive home is the riskiest part. In Barger’s study of first-year doctors, each extended shift scheduled in a month raised the monthly risk of a crash on the commute home by about 16%. Get a lift if you can, nap before you drive if you can’t, and see the night-shift guide for the dark room and the rest of the morning.

Then expect recovery to take more than one night. In a lab study by Banks and colleagues (2010), people limited to 4 hours in bed for five nights had still not fully recovered on attention, sleepiness and fatigue measures after a single 10-hour night in bed. A week of broken on-call nights isn’t the same experiment, but it points the same way: one long sleep helps, and it may not be enough.

If you are on call often and your sleep doesn’t recover between stretches, raise it with your employer’s fatigue policy and with a doctor. The American Academy of Sleep Medicine’s page on shift work disorder describes when poor sleep around work hours becomes a clinical problem.

Where AfterShift fits

On-call is a shift type in AfterShift, and it changes how the app treats the whole window around it. Calendar import recognises event titles such as on call, standby, backup, Bereitschaft or päivystys, and you can mark any shift as on-call yourself. When the window between your shifts contains an on-call shift:

• The Shift Recovery Score is capped at 75 and the Sleep Score at 84, so neither can read Excellent. I did that on purpose. The studies above find on-call sleep is worse even before any call comes, and a perfect-looking number in a week of broken nights would be the app claiming to know more than it does.
• The plan shows a flexible rest window instead of a set main sleep, and the nap suggestion says short naps are often more reliable on call. The short-window warning is switched off, because the uncertainty is expected.
• In Premium, the playbook switches to a standby routine when an on-call shift starts within the next 12 hours: lay out what you’ll need and keep the path to the door clear, keep caffeine for the shift, and wind down lightly so you stay easy to wake.
• Three or more on-call shifts in seven days count as an on-call week, and the app notes that recovery may come more slowly.

Naps you log count toward the score like any other sleep, which matters on call, where they may be most of what you get. The methodology page explains the caps, and the rotating schedules guide covers the rosters that on-call weeks usually sit inside.