Sleep consistency

Late Fridays and long lie ins move your body clock about. Compare your work nights with your nights off and see how big the shift is.

Your details

Bedtime on work nights
Wake time on work days
Bedtime on nights off
Wake time on days off

Bedtimes after midnight count as the same night, so 00:30 on a Friday is Friday night.

Work nights compared with nights off

2 h 15 min

shift in the middle of your sleep between the two (social jetlag)

  • Sleep on work nights8 h 30 min
  • Sleep on nights off9 h
  • Mid point, work nights02:45
  • Mid point, nights off05:00
  • Wake time difference2 h 30 min
  • Weekly average a night8 h 39 min

Researchers call this gap social jetlag: your body clock is asked to change time zone every weekend. The NHS advice for better sleep is to wake up and get up at the same time every day, and not to sleep in after a bad night. Bringing the weekend wake time within an hour of the weekday one is a good first step.

See your GP if changing your sleep habits has not helped, you have had trouble sleeping for months, or it is making it hard to cope. If you feel sleepy while driving, stop somewhere safe.

The working

Bed 22:30 to 07:00 on work nights, 00:30 to 09:30 on nights off

Work nights give 8 h 30 min with a mid point of 02:45. Nights off give 9 hours with a mid point of 05:00. The difference between the two mid points is 2 h 15 min of social jetlag, as if you flew two time zones west every weekend and back on Monday.

What social jetlag means

From the research

Researchers coined the term for the gap between the sleep timing your body clock wants on free days and the timing work or school imposes. They measure it by comparing the middle of your sleep on work days with the middle on free days, which is exactly what this page does.

Bringing it closer

Small steps

  • Keep your weekend wake up time within about an hour of your weekday one
  • Get outside in daylight soon after waking, especially at weekends
  • If you need more sleep at the weekend, go to bed a bit earlier rather than lying in
  • The NHS advice is to get up at the same time every day

Read with care

What this cannot tell you

  • Measure sleep qualityIt works out timing from what you type in.
  • Diagnose a sleep disorderLong term poor sleep needs a GP.
  • Know your shiftsIf you work nights, use the shift work sleep planner instead.

Questions

Common questions

What is social jetlag?

The difference between the middle of your sleep on work days and on free days. It is like changing time zone every weekend.

Is it bad to lie in at the weekend?

An occasional lie in is fine. The NHS advises getting up at the same time every day, as regular timing helps your body clock.

How consistent should my sleep be?

There is no official number, but keeping your wake up time within about an hour across the week is a sensible aim.

How much sleep do adults need?

Most adults need 7 to 9 hours a night.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

When to see a GP about sleep

See your GP if changing your sleep habits has not helped, you have had trouble sleeping for months, or it is affecting your daily life and making it hard to cope. If you feel sleepy at the wheel, stop somewhere safe.

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