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Social jetlag calculator

See how far your sleep moves between workdays and days off. Enter both schedules and get the gap between your two sleep midpoints. No signup needed.

On workdays

I fall asleep around

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I wake up at

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On days off

I fall asleep around

Drag or scroll to adjust. Tap the time to type.

I wake up at

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Your two nightsEach sun marks the middle of that sleep.

Dashed: workdays, 11:30 PM to 6:30 AM. Solid: days off, 1:00 AM to 9:30 AM.

2 h 15 min

Social jetlag

Your sleep midpoint moves from 3:00 AM on workdays to 5:15 AM on days off. That is a shift about the size of flying 2 time zones west for your days off, then back.

Workday midpoint
3:00 AM
Days-off midpoint
5:15 AM
Extra sleep on days off
1 h 30 min

Ways to shrink the gap

  1. 1By 7:30 AM on days offWake within an hour of your workday timeOn days off you wake 3 h later than on workdays.
  2. 2Soon after you wake, days off tooGet outside in the morning lightLight in the first hour after waking is the main thing that keeps your body clock on time.
  3. 3Friday and SaturdayShort on sleep? Go to bed earlierYou get more sleep and still wake and get light near your usual time.
  4. 4Late on nights before a day offKeep the lights lowBright lights and screens late at night push your body clock later.

Shrink the gap with a plan

A steady wake time and the right light at the right hour do most of the work. Answer a few questions and Calibrate builds a daily plan around the times you have to keep.

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Related reads: Does sleeping in on weekends make up for lost sleep? and How much morning sunlight you need.

How social jetlag is measured

Workday midpoint

The middle of your sleep before a workday

Days-off midpoint

The middle of your sleep before a day off

Social jetlag

The gap between the two 1

Learn more

Marc Wittmann, Till Roenneberg and colleagues named social jetlag in 2006 for the mismatch between the clock your body keeps and the clock your work or school sets 1. On days off you tend to sleep closer to your body's own timing, so the distance between the two midpoints is a simple way to see how far apart they are.

The calculator uses the midpoint because it captures both ends of the night. Going to bed an hour later and waking an hour later moves it by an hour; sleeping in without a later bedtime moves it by half the extra sleep.

Why the gap matters on Monday

Sleeping in moves your morning light later along with your wake time. In one study, sleeping in about three hours on Saturday and Sunday moved people's body clocks around 40 minutes later by Sunday evening 3. That is part of why Sunday night sleep and Monday mornings can feel harder.

Learn more

Later chronotypes usually have the biggest gaps, because their natural timing sits furthest from a typical working day 1,2. The chronotype quiz shows where your own timing sits.

How to shrink social jetlag

Keep your wake time on days off within about an hour of your workday one, and get outside soon after you wake on both kinds of day. If you need more sleep, go to bed earlier on Friday and Saturday rather than sleeping in. The weekend sleep-ins guide goes through it step by step, and the evening light guide covers the late-night side.

Social jetlag FAQ

What is social jetlag?

Social jetlag is the gap between when you sleep on workdays and when you sleep on days off. Researchers coined the term in 2006 because a big gap is a little like flying a few time zones west every weekend and back again on Monday.

How do you calculate social jetlag?

Find the middle of your sleep on workdays and on days off, then take the difference. If you sleep from 11:30 PM to 6:30 AM on workdays, the midpoint is 3:00 AM. From 1:00 AM to 9:30 AM on days off, it is 5:15 AM. The gap, 2 hours 15 minutes, is your social jetlag.

How much social jetlag is normal?

There is no official cutoff. Many people have some, and later types tend to have more, because a typical working day asks them to be up well before their body would wake. A gap under an hour means your two schedules line up fairly closely.

Does sleeping in on weekends make social jetlag worse?

Sleeping in moves your wake time and the morning light that comes with it, so it widens the gap. In one study, sleeping in by about three hours on a weekend moved people's body clocks around 40 minutes later by Sunday evening. Going to bed earlier instead of waking later gets you more sleep without that shift.

Is this social jetlag calculator medical advice?

No. It shows the difference between two times you enter, as wellness education. If you often feel exhausted even after long weekend sleeps, or fall asleep when you do not mean to, talk with your health care provider.

References

  1. Wittmann M, Dinich J, Merrow M, Roenneberg T (2006). Social jetlag: misalignment of biological and social time. Chronobiology International, 23(1-2), 497-509. doi.org/10.1080/07420520500545979
  2. Roenneberg T, Pilz LK, Zerbini G, Winnebeck EC (2019). Chronotype and social jetlag: a (self-) critical review. Biology, 8(3), 54. doi.org/10.3390/biology8030054
  3. Taylor A, Wright HR, Lack LC (2008). Sleeping-in on the weekend delays circadian phase and increases sleepiness the following week. Sleep and Biological Rhythms, 6(3), 172-179. doi.org/10.1111/j.1479-8425.2008.00356.x

This calculator is for wellness education and shows the gap between times you enter, not medical advice. It does not diagnose or treat any condition.

Social Jetlag Calculator: Workdays vs Days Off | Calibrate