Why is it harder to wake up for a shift?
Your body clock sets a time for sleep and a time for wakefulness. Shift work puts the alarm in the wrong part of that cycle.
- A 2019 review reports that sleep inertia effects are greatest during the biological night, near the daily low in core body temperature.
- The same review reports that prior sleep loss makes sleep inertia worse. Shift workers often sleep less, because they sleep in the daytime or go to bed early.
- A 2014 review reports that sleepiness on night shifts is at its maximum at the end of the night.
Shift work is common. The 2014 review states that between 15 and 30% of adult workers do some type of shift work.
What does the research say for each situation?
| Situation | What the reviews report | What you can do |
|---|---|---|
| Early shift, alarm before 5 am | You wake near the low point of your body clock. | Go to bed earlier on the days before. Plan more time after the alarm. |
| Night shift, sleep in the daytime | Daytime sleep is often shorter, and sleep loss makes waking harder. | Make the room dark and quiet. Keep the same sleep time on each night-shift day. |
| Nap before or during a shift | Naps of less than 30 minutes cause less sleep inertia. | Set an alarm for a short nap. |
| First minutes after the alarm | Performance is lower. Full recovery can take an hour or more. | Do not drive or do safety tasks directly after you wake, if you can avoid it. |
What reduces grogginess after the alarm?
The 2019 review found no clear proof for any method that you use after you wake, such as light or sound. The method with the most support is one that you use before sleep: caffeine directly before a short nap. The caffeine takes effect at about the time when you wake.
Caffeine is not safe for everyone. Ask a doctor if you have a health condition or are pregnant. See what sleep inertia is and how long it lasts.
How do you set alarms for changing shifts?
- Set one alarm for each shift type, with a clear label such as "Early shift".
- Check the alarm each evening against your roster.
- Use a second alarm on a different device for shifts that you must not miss.
- Put the phone where you must stand up to reach it.
If you share a bedroom with a person on a different schedule, a loud or talking alarm can wake that person too. A vibration alarm on the wrist is quieter.
Does Waker work for shift workers?
Waker is an iPhone alarm app. When your alarm rings, you tap “Talk to Waker” and have a voice conversation about your day. There is no snooze button. You set the time and the days on which each alarm repeats, so a roster that changes each week needs a change to your alarms. Waker has no roster import. The alarm rings on silent and in a Focus, and the conversation needs an internet connection. No study has tested Waker with shift workers.
When should you see a doctor?
A 2014 review gives an estimate that 2 to 5% of workers have shift work sleep disorder. The signs are strong sleepiness or disturbed sleep for a month or more, related to the work schedule. Speak to a doctor if this describes you, or if you fall asleep at work or at the wheel.
Common questions
Is it normal to feel worse after a night-shift alarm than after a day alarm?
Yes. Sleep inertia is strongest in the biological night and after too little sleep. Both conditions are common in shift work.
How long should a nap before a shift be?
The 2019 review recommends naps of less than 30 minutes to limit sleep inertia. Set an alarm, and allow time to become alert after the nap.
Do many alarms help on early shifts?
Many alarms break the last part of your sleep. One alarm and one backup on a different device are enough. See if it is bad to set many alarms.
Why can I not wake up, even with a loud alarm?
Too little sleep is the usual reason. See why you cannot wake up to your alarm.
Sources
- Sleep inertia: current insights. Hilditch and McHill, Nature and Science of Sleep, 2019.
- Impacts of shift work on sleep and circadian rhythms. Boivin and Boudreau, Pathologie Biologie, 2014.