Work backwards from the shift, not forwards from the alarm. Shift start, minus how early you need to be there, minus the commute, minus your real getting-ready time, minus a buffer for grogginess. That last subtraction is the one people skip.
Fill this in once and it also gives you the bedtime that makes the wake-up survivable, which is usually the number that changes behaviour.
Set your alarm for—
That is the evening before your shift starts.
—Start getting readyOut of bed and moving, not still deciding.
—Leave the houseIf you are still home after this, you are late.
—ArriveEnough margin to change, hand over and start.
—Shift startsThe fixed point everything else works back from.
Lights out by — to hit your sleep target, allowing 15 minutes to actually fall asleep. Total run-up from alarm to shift start: —.
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The buffer is the part that matters
Most people plan the commute and the shower accurately, then set the alarm for the exact minute the plan starts. That assumes you are fully functional the second the alarm goes off, and you are not.
Sleep inertia is the grogginess in the period after waking, and CDC guidance written for nurses working long hours warns that the impairment can be at its worst in the first 15 to 30 minutes. For a shift worker that window frequently contains a drive. Building ten minutes of slack into the plan is not indulgence, it is the difference between the plan holding and the plan collapsing on the first bad morning.
Time your routine instead of estimating it
Do it once, on a normal morning, from the moment you get out of bed to the moment you are at the door. Almost everyone is out by five to fifteen minutes, always in the optimistic direction. Put the real number in the field above.
The bedtime line is the uncomfortable one
A 4:50 a.m. alarm and an eight-hour target means lights out around 8:35 p.m. Most people read that and immediately know they will not do it, which is useful information: it means the morning was never going to be easy, and the fix is upstream of any alarm.
If the bedtime is genuinely impossible because of the rota, that is worth knowing too. It tells you the wake-up is going to be hard for structural reasons rather than because you are bad at mornings.
When this is worth raising with a doctor
Everything on this page assumes you are getting enough sleep and still struggling to wake. If you sleep a full night and still wake unrefreshed, feel sleepy during the day, or someone has told you that you snore loudly or stop breathing in your sleep, that is worth a GP appointment rather than another app. The NHS pages on excessive daytime sleepiness and sleep apnoea describe what to look for. Mornio is not a medical product and cannot diagnose or treat anything.
Once you have the number
Set the alarm the moment you learn the shift, not the night before. This single habit prevents more missed shifts than any app feature, and it is covered in the shift workers' guide.
Check am versus pm. Around night shifts a 6 could plausibly be either.
Work backwards, not forwards. For a 6 a.m. start with a 20 minute commute, arriving 10 minutes early, 30 minutes to get ready and a 10 minute buffer for grogginess, you need to be awake at 4:50 a.m. Change any of those four numbers in the calculator and it recalculates. The number people get wrong is the buffer: sleep inertia means the first 15 to 30 minutes after waking are your least capable, so the buffer belongs in the plan rather than being stolen from the commute.
How much time should I leave between waking up and leaving the house?
However long your routine genuinely takes, plus a buffer of at least 10 minutes. Time yourself on a normal morning rather than estimating, because almost everyone underestimates. If you are driving, the CDC's guidance for nurses is worth taking seriously: sleep inertia can be at its worst in the first 15 to 30 minutes after waking, which is exactly when many shift workers get in a car.
What time should I go to bed for an early shift?
The calculator subtracts your sleep target plus 15 minutes to fall asleep from your wake-up time. For a 4:50 a.m. wake-up on 8 hours, that is a 8:35 p.m. lights-out. That number is often the useful shock: people plan the morning carefully and then leave the bedtime to chance, which is the actual reason the morning is hard.
Does this work for night shifts?
Yes, the arithmetic is the same and the calculator handles start times that push your wake-up into the previous day. What it cannot do is tell you when to sleep during daylight, which is the genuinely hard part of night work. That is covered in the shift workers' guide.
Is anything I type here sent anywhere?
No. The calculation runs in your browser in JavaScript that ships with the page. There is no form submission, no account, and no cookie storing your shift times. You can close the tab and nothing about your schedule persists.
App Store details change without notice. Everything above was checked on 30 July 2026 — if you spot something out of date, tell us at support@mornioapp.com and we’ll correct it. Written and published by the Mornio team. Last reviewed 30 July 2026.