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Social jetlag calculator
Social jetlag is the difference between the midpoint of your sleep on free days and on work days. It was named in 2006 by Wittmann, Dinich, Merrow and Roenneberg, and it is common: in 64,110 adults with regular schedules, 69% had at least one hour and a third had two hours or more. Enter a typical work night and free night below, including how long you take to fall asleep, and this page computes your social jetlag, the sleep-corrected version, your chronotype, and your weekly sleep loss with the Munich ChronoType Questionnaire formulas.
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Social jetlag
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Social jetlag 1h 38m, Moderate social jetlag
Your social jetlag
Example week — change the times to see yoursModerate social jetlag
Between one and two hours, where a little over a third of adults land. In the studies that use this group, its links with health outcomes are small or not statistically clear.
On free days, the middle of your sleep comes 1h 38m later than on work days. Every week your body shifts later and then back again, a bit like flying across 2 time zones and back without leaving home.
Without catch-up sleep
1h 00m
The shift with the extra free-day sleep taken out
Your body clock
04:18
Middle of your sleep when nothing wakes you. Close to the most common time, 04:14.
Average sleep
7h 36m
Per night, across the whole week
Sleep debt
1h 47m
Per week: how far short nights fall below your weekly average, added up
About 38m of the shift is catch-up sleep. You sleep longer on free days, which mostly makes up for short work nights. The other 1h 00m is your sleep starting later. The researchers who defined social jetlag say the cause is work-day schedules cutting sleep short, not the weekend lie-in, so sleeping in less is not the fix they recommend.
- Asleep
- Falling asleep
- Middle of sleep
- Your body clock
The gap between the two black lines is your social jetlag: how far the middle of your sleep moves between work nights and free nights.
The week above is an example, so the page has something to show. Overwrite it with your own times. Everything is computed in this browser, nothing is uploaded, and nothing is saved, so reloading brings the example back.
Reading the result
What your number means
- Under 1 hour
Low social jetlag
Your sleep keeps nearly the same timing on work days and free days. Studies that compare groups use under one hour as the reference, and only about three in ten adults land here.
- 1 to 2 hours
Moderate social jetlag
Between one and two hours, where a little over a third of adults land. In the studies that use this group, its links with health outcomes are small or not statistically clear.
- 2 hours or more
High social jetlag
Two hours or more, like about a third of adults. It is the cut-off most studies use, and the group where links with mood, weight, and heart health show up most often. Those links are associations, not proof the shift causes them.
The evidence
What social jetlag is linked to, and how strongly
- 01
Weight: small and consistent
A 2024 meta-analysis of 43 studies and 231,648 people found social jetlag correlated with BMI at r = 0.12, with about 1.2 times the odds of overweight. A 2023 meta-analysis of 68 studies put it at roughly half a BMI point, but found no link with diabetes or metabolic syndrome as diagnoses.
- 02
Mood: depends who you ask
In young people, two hours or more went with 1.44 times the odds of depressive symptoms across eight studies. Across all ages, a 2025 meta-analysis of 25 studies found a correlation of 0.05, which its authors said lacks clinical utility. How big the link is depends heavily on who is studied.
- 03
Heart: one large study
In 51,562 UK Biobank adults whose sleep was measured by a wrist sensor, two hours or more of social jetlag went with a 30% higher risk of new cardiovascular disease, independent of how long they slept. It is the strongest study so far, and it is still observational.
Cause or correlation?
The method
The formulas, and what this version cannot see
Mid-sleep and social jetlag
sleep onset = lights out + minutes to fall asleep
mid-sleep = sleep onset + sleep duration / 2
social jetlag = | mid-sleep on free days − mid-sleep on work days |
Mid-sleep is the clock time halfway through your sleep. It is the MCTQ’s marker of where your body clock sits, and comparing it between work days and free days measures how far your schedule pulls you away from it. This page measures clock times from noon, so a night that crosses midnight is one continuous span.
The two corrections
average sleep = (work-day sleep × work days + free-day sleep × free days) / 7
chronotype (MSFsc) = free-day mid-sleep − (free-day sleep − average sleep) / 2
sleep-corrected jetlag = | free-day onset − work-day onset |, or | free-day wake − work-day wake |
Long free-day sleep is partly catch-up for short work nights, and catch-up sleep pushes your mid-sleep later than your clock alone would. The chronotype correction removes it when you sleep longer on free days. The sleep-corrected jetlag compares the end of sleep that is not stretched by catch-up: onsets when free-day sleep is longer, wake times when it is not.
Sleep onset is not bedtime. The questionnaire asks when you are ready to sleep and how long you take to fall asleep, and adds the two. The authors’ own review found that 4 of 26 social jetlag studies it checked used bedtime or time in bed instead, which overstates the night. That is why this calculator has a minutes-to-fall-asleep field.
These are your typical times, from memory. The MCTQ has been checked against sleep diaries, wrist sensors and melatonin timing, and it holds up as a population tool. For one person, typed estimates of a typical week are rougher than a fortnight of logged nights.
It is not for shift work. The standard questionnaire assumes a regular week with at least one work day and one free day. Rotating or night shifts have their own version, the MCTQShift, and this page does not implement it.
An alarm on free days hides your chronotype. If something wakes you on free days, free-day sleep is not your body’s own choice, and the MCTQ does not compute chronotype at all. Social jetlag is still shown, but read it as a lower bound.
It is a proxy. Social jetlag measures how far your sleep moves, not your body clock directly, and the clock itself shifts with sleep timing within a couple of days. The research norms also come mostly from European and North American online samples.
Sources for the method
- [1]Social jetlag: misalignment of biological and social time
Wittmann, Dinich, Merrow & Roenneberg, 2006 · Chronobiology International 23(1–2), 497–509
The paper that named social jetlag and defined it as the difference between mid-sleep on free days and on work days.
- [2]A marker for the end of adolescence
Roenneberg, Kuehnle, Pramstaller, Ricken, Havel, Guth & Merrow, 2004 · Current Biology 14(24), R1038–R1039
Defines the sleep-debt-corrected chronotype (MSFsc) this page computes, and shows chronotype getting later until about age 20 (19.5 for women, 20.9 for men), then earlier again.
- [3]Social jetlag and obesity
Roenneberg, Allebrandt, Merrow & Vetter, 2012 (erratum 2013) · Current Biology 22(10), 939–943; erratum 23(8), 737
The full MCTQ variable set used here, including average weekly sleep and weekly sleep loss, and the prevalence figures: 69% of 64,110 adults had at least one hour of social jetlag, a third two hours or more. The 2013 erratum (doi 10.1016/j.cub.2013.04.011) corrects the MSFsc formula to use average weekly sleep, which is the version implemented here.
- [4]Social jet lag: sleep-corrected formula
Jankowski, 2017 · Chronobiology International 34(4), 531–535
The sleep-corrected social jetlag: the difference in sleep onsets when free-day sleep is longer, in wake times when work-day sleep is longer. For the remaining combinations this page follows the rOpenSci mctq package and uses the onset difference.
- [5]Epidemiology of the human circadian clock
Roenneberg, Kuehnle, Juda, Kantermann, Allebrandt, Gordijn & Merrow, 2007 · Sleep Medicine Reviews 11(6), 429–438
More than 55,000 mostly central-European respondents. The most common free-day mid-sleep was 04:14, with 35% of people earlier and 50% later, which is the reference point the chronotype tile compares you to.
- [6]Chronotype and social jetlag: a (self-) critical review
Roenneberg, Pilz, Zerbini & Winnebeck, 2019 · Biology 8(3), 54
The method’s authors on its limits: sleep onset is not bedtime, the sleep-corrected version is still debated, the health evidence is mostly cross-sectional, and the problem is work-day constraints rather than sleeping in.
Sources for the evidence
- [1]Social jetlag and obesity: A systematic review and meta-analysis
Arab, Karimi, Garaulet & Scheer, 2024 · Obesity Reviews 25(3), e13664
43 studies, 231,648 people. Social jetlag correlated with BMI at r = 0.12, and with about 1.2 times the odds of overweight or obesity.
- [2]The association between social jetlag and parameters of metabolic syndrome and type 2 diabetes: a systematic review and meta-analysis
Bouman, Beulens, Groeneveld, de Kruijk, Schoonmade, Remmelzwaal, Elders & Rutters, 2023 · Journal of Sleep Research 32(3), e13770
68 studies. Social jetlag went with about 0.5 kg/m² higher BMI and 1.1 cm more waist, but not with obesity, type 2 diabetes or metabolic syndrome as diagnoses. The authors rate the evidence as low.
- [3]Social jet lag is associated with incident cardiovascular disease independent of sleep duration and cardiac genetic risk
Kumar & Krishnamurthy, 2026 · Journal of Internal Medicine 300(3), 360–378
51,562 UK Biobank adults, social jetlag measured by wrist accelerometer, 3,853 new cases of cardiovascular disease. Two hours or more went with a 30% higher risk (HR 1.30), independent of sleep duration and genetic risk.
- [4]Social jetlag and depressive symptoms among young people: a systematic review and meta-analysis
Sun, Yang, Yu, He, Luo, Zhang, Chen & Tung, 2025 · BMC Psychiatry 25, 664
Eight studies of 10- to 24-year-olds. Two hours or more went with 1.44 times the odds of depressive symptoms; one to two hours with 1.05.
- [5]Social jet lag and mental health outcomes: A systematic review and meta-analysis
Gao, Gao & Zeng, 2025 · Acta Psychologica 259, 105419
25 studies across ages. Social jetlag correlated with depression at r = 0.049, about 0.24% of the variance, which the authors describe as lacking clinical utility.
- [6]Social jetlag is associated with an increased likelihood of having depressive symptoms among the Japanese working population: the Furukawa Nutrition and Health Study
Islam, Hu, Akter, Kuwahara, Kochi, Eguchi, Kurotani, Nanri, Kabe & Mizoue, 2020 · Sleep 43(1), zsz204
1,404 workers. The source of this page’s three bands: under 1 hour as the reference, 1 to 2 hours (odds ratio 1.30, not statistically clear), and 2 hours or more (2.14).
- [7]Weekend sleep extension, social jetlag, and incidence of coronary calcium score: the ELSA-Brasil study
Peixoto de Miranda, Parise, Santos, Giatti, Aielo, Cunha et al., 2025 · Sleep 48(5), zsaf039
1,832 adults with actigraphy, followed up. Social jetlag was only weakly linked to new coronary calcium, while more than 90 minutes of weekend catch-up sleep went with lower odds of it (OR 0.62).
- [8]Resetting the late timing of ‘night owls’ has a positive impact on mental health and performance
Facer-Childs, Middleton, Skene & Bagshaw, 2019 · Sleep Medicine 60, 236–247
A randomised trial that moved late sleepers’ schedule about two hours earlier. Depression and stress scores improved. It changed sleep timing, not social jetlag as such.
This is one typical week. Your real weeks are not typical.
You typed one work night and one free night, which is what the questionnaire asks for. Habit Pocket logs every bedtime and wake time as a real clock time on iPhone and the web, and draws them as a candle chart, so the weekend drift shows up as it happens rather than as an average you had to estimate.
5 habits free, forever. No credit card. Your data stays private.
FAQ
Social jetlag, answered
Social jetlag is the gap between when you sleep on work days and when you sleep on free days, measured between the midpoints of the two nights. The term was coined in a 2006 paper by Wittmann, Dinich, Merrow and Roenneberg, because the weekly shift works like travel: sleep that sits two hours later at the weekend has to move back two hours by Monday, as if you had crossed two time zones. It is common. In 64,110 adults with regular schedules, 69% had at least an hour of it and a third had two hours or more.
Work out the mid-sleep for a typical work night and a typical free night, then take the difference. Sleep onset is the time you are ready to sleep plus the minutes it takes you to fall asleep, sleep duration runs from onset to waking, and mid-sleep is onset plus half the duration. If you fall asleep at 23:30 and wake at 06:45 on work days, mid-sleep is about 03:08; at 00:30 to 09:00 on free days it is 04:45; social jetlag is about 1 hour 38 minutes. This calculator does it for you with the Munich ChronoType Questionnaire formulas.
Some is close to universal. In the largest study, 69% of adults had at least one hour and about a third had two hours or more. There is no validated healthy limit. Research usually compares under one hour, one to two hours, and two hours or more, and the health links that do appear show up mostly in the two-hours-or-more group.
It is linked with some health outcomes, weakly and mostly in studies that measure everything at one time. Meta-analyses find a small, consistent link with BMI (a correlation of about 0.12) but not with diabetes as a diagnosis; links with depression are clearer in young people than across all ages; and one large UK Biobank study found 30% higher risk of new cardiovascular disease at two hours or more. No trial has yet shown that reducing social jetlag itself improves health.
It is a 2017 version of the measure by Konrad Jankowski that removes the part of the gap caused by sleeping longer on free days. Plain social jetlag compares mid-sleeps, so a long weekend lie-in that repays a week of short nights pushes it up. The corrected version compares sleep onsets when free-day sleep is longer, and wake times when work-day sleep is longer. The method’s original authors still consider the question open, so this page shows both numbers.
It is your mid-sleep on free days, corrected for catch-up sleep, which the Munich ChronoType Questionnaire uses as its measure of chronotype (MSFsc). An earlier time means an earlier body clock. In more than 55,000 mostly European respondents, the most common free-day mid-sleep was 04:14, with about 35% earlier and 50% later. Chronotype gets later through the teens until about age 20, then earlier again through adulthood.
Not on the evidence so far. The researchers who defined social jetlag argue the problem is work-day schedules that cut sleep short, and that the weekend lie-in is mostly the body repaying that debt. In a Brazilian study that followed 1,832 adults, more than 90 minutes of weekend catch-up sleep went with lower odds of new coronary calcium, not higher. The sleep-corrected number on this page shows how much of your gap is catch-up rather than a later clock.
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Last updated October 2026 · I built this calculator myself, and every formula and figure on this page links to the paper it comes from · By Bohdan Stefaniuk