During the week, you try to go to bed early enough so that you feel more or less refreshed the next day when your alarm clock rings and you have to get up. But on the weekends, you can go to bed when you want to. And you can sleep as long as you want to. That is your weekly rhythm. Week after week. And this is the same weekly rhythm not just for you but for nearly everyone else. But, unfortunately, this is also the weekly rhythm that leads to social jet lag.
What is social jet lag? Social jet lag is the chronic misalignment between the sleep you get during the week and on weekends. During the week, your social schedule makes you wake up earlier than your body is ready. And on the weekend you go to bed later and you sleep longer to catch up. Your sleep changes as if you travel across time zones.
How to overcome social jet lag? For social jet lag, the problem to overcome is that you don’t get enough sleep during the week because you can’t fall asleep early enough for when you have to get up the next day. Get the right light exposure and eat at the right time to fall asleep earlier and improve your sleep quality. And nap during the day to repay your sleep debt.
Read on to get a full understanding of:
- What social jet lag is and how it affects your sleeping cycles
- Which factors lead to you to develop social jet lag
- Why social jet lag does not affect early chronotypes
- What the consequences of social jet lag are
- How you can overcome social jet lag with four practical tips
- My personal experiences and your key takeaways
You might be surprised to see how many of the factors you meet that lead to social jet lag. Or that only a small minority is not affected by it. But don’t worry, the practical tips, later on, will help you to minimize your social jet lag. Even if you didn’t know until now that it also affects you. But let’s not get ahead of us. Let’s start with what social jet lag is.
What Is Social Jet Lag
What Is Social Jet Lag
You have probably heard about your circadian rhythm, right? Well, social jet lag is the most frequent type of living against your circadian rhythm
If you are like eighty-five percent of the people
This difference in your sleep can easily be a few hours apart. Because this pattern is so much like time-zone travel, it was coined social jet lag by Till Roenneberg
To have a closer look at your social jet lag, let me introduce you to your midsleep point, which is middle between when you fall asleep and when you wake up. This is commonly used by chronobiologists to have a look at your sleep as an expression of your chronotype.
In this post, you can read all about “What Are Chronotypes and How to Find Out Yours.”
To calculate your midsleep point, you simply have to:
- Write down when you fall asleep.
- Write down when you wake up.
- Take the middle point between when you fell asleep and when you woke up.
Your midsleep point largely depends on your chronotype. Let’s have a look at a few examples of chronotypes and their midsleep points.
|Early chronotype||Middle chronotype||Late chronotype|
|Asleep at:||10:00 pm||12:00 pm||04:00 am|
|Awake at:||06:00 am||08:00 am||10:00 am|
|Midsleep:||02:00 am||04:00 am||06:00 am|
Now it’s your turn: what are your average midsleep points during the week and on weekends?
- For the last seven days, write down when you fell asleep and when you woke up (to your best knowledge).
- Then calculate your midsleep points for each of these days, just as above.
- Take the average of your midsleep points for those days when you had to get up for work or school.
- Take the average of those days when you could self-select your sleep timings.
Now, how do those midsleep points look like for your work days and your free days? Are there any differences? If you are like most of us, then there are. And this difference is the extent of your social jet lag.
Eighty-seven percent of the population suffers from social jetlag. For over forty percent, their social jet lag is two hours or more (the difference between midsleep points on work days and free days). And for over fifteen percent, this difference is three hours or more.
It is as if their body wakes up every Monday either two or three time zones further to the east. And travels to the west every Friday evening. Week after week. But, unlike with real jet lag, there are no different external signals for your body to adjust to those changes.
Let’s see what that looks like in real life.
In their landmark paper about “Entrainment of the Human Circadian Clock,” Till Roenneberg and Martha Merrow, also studied the midsleep points of more than 60,000 individuals through their MCTQ (Munich ChronoType Questionnaire) database – a number that has grown to over 300,000 now. And they plotted them between work days and free days.
The outcome is the following graph they nicknamed “the scissors of sleep.”
Depending on your chronotype, both your midsleep points and your sleep duration can be very different between your work (or school) days and your free days. And if you belong to the majority of eighty-seven percent of the population, you suffer from social jet lag and your midsleep point is at least two hours later on the weekend.
First of all, your chronotype and the duration of your sleep are two independent variables – at least when it comes to your overall sleep duration during one full week. In short, the later your chronotype (your midsleep point on free days), the fewer hours you sleep on your work days. And the more sleep debt you accumulate during these days.
And the more sleep debt you have, the more you need to catch up on sleep during your free days. This means that you will have to sleep longer on these days.
And if you are an early chronotype, then congrats! You belong to the lucky thirteen percent that does not suffer from social jet lag.
But if you are a later chronotype, most likely your work (or school) times are too early. Just like they are for the vast majority of the population. And the “scissors of sleep” above show that the later your chronotype, the greater the difference between your work (or school) times and your free times. Aka, the greater is the social jet lag that you experience.
Why Are You Affected By It
Why Are You Affected By Social Jet Lag
Now you might wonder, why is it that something like social jet lag exists in the first place?
Well, it is because there are three different time systems that your body interacts with every day: sun time, social time, and your internal time:
- Sun time is the time of nature. Your body receives visual feedback through the position of the sun in the sky and the respective sunray pattern.
- Internal time is the time your body thinks it is. For this, you have an internal biological clock. Through your biological clock, your body maps its internal time. And through its internal time, your body develops your daily rhythm – your circadian rhythm.
- Social time is the time you live by based on your environment and social commitments. This could be anything from work or study schedule to time commitments with friends and family.
And in the case of social jet lag, these three times are not aligned.
Your social time tells you when you need to wake up during your work (or school) days. This is something fixed that you most likely can’t easily change. At least not on a day-to-day basis.
Your internal time tells you when you are able to fall asleep. And the later of a chronotype you are, the later you will be able to fall asleep. Just as we have seen above.
Your sun time is your local time of day. And here lies one of the problems for you. One that you can change. You are most likely not aligned with sun time: you don’t get enough natural light during the day and too much artificial light at night. The result? You become a later chronotype, which means that you will only be able to fall asleep even later.
Have a look at the post about “How Does Your Circadian Rhythm Work” for a full picture.
Why It Only Affects Late Chronotypes
Why Social Jet Lag Only Affects Late Chronotypes
Your chronotype determines when you are able to fall asleep. And your alarm clock determines when you have to wake up. The later your chronotype, the less sleep you get. And the more sleep you’ll have to catch up during the weekend.
Here is how this looks for late chronotypes (midsleep later than 3 am):
|During the week||On the weekends|
|Go to sleep||The later your chronotype, the later you fall asleep||The later your chronotype, the later you fall asleep|
|Wake up||You need an alarm clock to wake up||The later your chronotype, the later you wake up|
|Result||The later your chronotype, the less sleep you get||You have to catch up on sleep|
The later your chronotype is, the later you fall asleep. Your working hours, on the other hand, are (on average) the same for everyone. Independent on chronotypes. This means that the later your chronotype is, the less you sleep during the week. And it also explains why 85 percent of the population needs an alarm clock to wake up: their chronotypes are simply too early for their working hours.
On the weekend, you then have the opportunity to catch up on sleep. The less sleep you get during the week the more your sleep debt is. And the more you sleep during the weekend. For some people, this even means sleeping through half of their free days to catch up on sleep.
Here is how this looks for early chronotypes (midsleep earlier than 3 am):
|During the week||On the weekends|
|Go to sleep||The earlier your chronotype, the earlier you fall asleep||Social pressure makes you sleep later than your early chronotype|
|Wake up||You are ready and awake without an alarm clock||The earlier your chronotype, the earlier you wake up|
|Result||You get enough sleep||The earlier your chronotype, the less sleep you get|
If you are an early chronotype then the story is the other way round for you. You can fall asleep early enough during the week and get enough sleep. And you can wake up without an alarm clock.
But during the weekend, social commitments prevent you from falling asleep as early as you want to. Or better as early as your chronotype tells you to. But you then wake up as early as ever the next morning. And in this way, you don’t get enough sleep on your weekends.
In the graph above (“the scissors of sleep”), you have seen the statistical summary of how social jet lag looks like. And in the last paragraphs, you have seen the reasons why. Let’s now have a look at two studied cases, one early and one late chronotype, to see what social jet lag looks like in real life over a few weeks.
Each of those bars represents one night of sleep. Nights during the week are shown as black bars and nights on weekends are shown as gray bars.
Can you already see the difference in chronotype and social jet lag?
Let’s have a look at the left graph first, the early chronotype. Do you notice how the wake-up time seems to naturally fluctuate around some time before 6 am? And how the sleep times also don’t vary too much? Besides for some weekend nights (gray bars), where this person fell asleep later and got less sleep. Did you also notice how the average sleep length (length of each bar) is greater during the week than on weekends?
Now let’s have a look at how that works out on the right graph, the late chronotype. The story here is a much different one. During the week that person woke up pretty much exactly the same time every day – a clear signal for the usage of an alarm clock. And sleep times look very different for the weekends. They sleep much longer. Both in duration (to catch up on sleep) and when they wake up. And they also went to bed a bit later yet on the weekend.
In short, midsleep points are fairly similar for you during work (or school) days and on free days (weekend) if you are a person with an earlier chronotype. But if you are a person with a later chronotype, those midsleep points can vary greatly (just like in the example above). Or maybe also in your personal example you calculated and noted down.
So, which of these two categories do you belong to? And in case you are unsure at this point, I invite you to scroll back up to calculate your midsleep points. And then have a look again at how they differ.
Before we have a look at how to overcome social jet lag, let me first show you why you want to overcome it. Let me introduce you to the consequences of social jet lag on your life.
Why Are the Consequences
What Are the Consequences of Social Jet Lag
The immediate consequences of social jet lag are just like the normal jet lag you would experience when traveling across a few time zones. As many as your difference in midsleep points is to be precise. But without the actual air travel across those time zones. And, hence, also without the opportunity for your body to adapt.
You probably know the feelings of jet lag. The confused feeling in your body when you cross time zones. You might be overly tired during the day yet can’t easily fall asleep at night. You are hungry at times that don’t match your new environment. And even your cognitive and physical performance is worse. All of these are acute signals that your body didn’t adapt to the new time zone yet.
But the worst consequences of social jet lag happen over time. This is because, as opposed to normal jet lag, social jet lag is chronic. It happens every week as if you fly east every Monday morning and return home west every Friday evening. But without ever allowing your body to adapt.
If you have chronic social jet lag then:
- Your most obvious symptom is chronic sleep deprivation.
- You increase the risk of the development of cardiovascular diseases.
- You have negative metabolic changes that could lead to obesity and type 2 diabetes.
- You are at a higher risk for developing depression.
- You are more likely to engage in health-impairing habits such as smoking and excessive caffeine consumption.
And one additional problem of social jet lag is that you might perceive it as your normal state of being. You might perceive your current state of social jet lag how your life naturally is. Or at least you might have. But now you know better!
You have probably come across the following phrase many times: “I hate Mondays.” And probably nearly as often you might have come across one common answer: “It’s not the Monday that sucks, it’s your job.”
But maybe it’s not (or at least not only) your job, after all, maybe it’s your working schedule that comes with your job. And that leads to you chronically experiencing social jet lag, including all the adverse effects it has on you.
How to Overcome Social Jet Lag
How to Overcome Social Jet Lag
Let’s recap that you for you to experience social jet lag, you need to have social commitments (like work or school start times) that interfere with your natural sleep timings. This leads to two problems that we will have a look at now:
- Because of your rather late chronotype, you can’t fall asleep early enough during the week to get enough sleep until the next morning, when your alarm clock rings too early.
- This leads you to build up sleep debt during the week that you need to repay in one way or the other.
So, the biggest impact you can have to overcome your social jet lag either helps you to fall asleep earlier at night, to improve your sleep quality, or it helps you to repay your sleep debt.
Fall Asleep Earlier
How You Can Fall Asleep Earlier
As a short introduction to this topic: natural light in the first part of the day advances your chronotype. This means that light exposure helps you fall asleep earlier. But artificial light (especially blue screens) during the evening and night slows down your chronotype. This means that it postpones your sleep timing.
You can get the full story in a post I wrote about “What Are Chronotypes and How to Find Out Yours.”
Increase your natural light exposure as much as you can during the day. You are most likely not getting enough natural light during the day. Especially if you are working in an office or are staying inside most of the time. And the difference of light intensity (what counts for your circadian rhythm) between the inside and outside can hundred- to thousand-fold.
If you can, go outside as much as possible. If you are inside, move as close to the windows as possible. If you can’t do either, max out the lighting of your building. And if that’s also not possible, get some of those light showers that work on a small range, just for you.
And don’t reduce any possible light intensity that you could get. Don’t wear sunglasses until you have to (if it’s more dangerous without). Also, don’t wear glasses with a blue-light filter or coating in the first half of the day.
Check out tips #1 to #5 in the post about “How to Get Your Circadian Rhythm Back on Track” for more practical information.
Reduce your artificial light exposure during the evening and at night. Adapt any artificial lighting, especially your LEDs and screens, to cut down on light emissions. Use blue-filtering glasses to reduce how much of it gets through to your eyes.
Check out tips #6 to #9 in the post about “How to Get Your Circadian Rhythm Back on Track” for more practical information.
Improve Sleep Quality
How You Can Improve Your Sleep Quality
First off, the right daily light exposure will help you to improve your sleep quality. But there’s more to your sleep quality. And it is about when you eat.
Don’t eat too late in the evening. After you consume your last calories (any snacks and drinks with calories count too), your organs still need about two to three hours to process those calories. Only afterward they can switch into their repair and rejuvenate mode. And also when they are ready for the night, you will improve your sleep quality.
Check out tip #10 in the post about “How to Get Your Circadian Rhythm Back on Track” for more practical information.
Repay Sleep Debt
How You Can Repay Sleep Debt
Sleep debt simply is the difference between the amount of sleep your body needs and the amount of sleep you actually get. And sleep debt is also the reason why the graph with the “scissors of sleep” above shows such a huge difference between sleep duration on work (or school) days and on free days.
Take a nap during the day if you can’t get enough sleep during the night. This is one often overlooked way to repay your sleep debt. And if you take it during your mid-afternoon, you can also beat the daily low that naturally occurs at this time (also thanks to your circadian rhythm).
“A short nap during the day is one way to repay your sleep debt.”Satchin Panda
Just don’t sleep for too long in the afternoon. When you are able to fall asleep depends on your circadian rhythm (which you influenced with light and food as per above) and the sleep pressure you have built up. Normally you fall short on the circadian rhythm part. This is why those tips above will have such a positive effect on you. Don’t make it the lack of sleep pressure due to a too late and too long nap that interferes with your sleep.
My Personal Experiences
I loved doing sports early in the morning before work. Especially running outdoors. One of my favorite routes is running up to the top of a local mountain that I can reach from my house.
My typical day would start waking up early in the morning, some time before six am. Then I’d go out running for an hour or so. And I’d come home fully energized and ready to work. In the evenings, then, I used to be tired really early on. And fall asleep around ten pm.
And this routine was pretty much the same most weekends.
But then I got injured and couldn’t run anymore. The result? Instead of spending time outside running in the mornings – and catching plenty of natural light – I stayed in bed for longer.
One unexpected result? While I woke up nearly always earlier than my alarm clock could ring before this injury, that wasn’t the same anymore. Even though I had about ninety minutes more that I could sleep, the alarm clock still had to wake me up.
Why? Because I couldn’t fall asleep early enough anymore. And then I exposed myself to more artificial light. I slept so late that it cut short on my sleep. With every work day, I built up more sleep debt.
And on the weekends I then had to repay all that sleep debt. A typical case of experiencing social jet lag. If I only knew better back then…
How did I get out of this? With early morning walks! I started going out for a short ten to fifteen minute walk a few minutes after I woke up. And things changed for the better again. So much so, that I have still been doing those walks on nearly all days without an early morning run. And some work breaks have now also turned into outdoor walks.
Let me quote Till Roenneberg, one of my favorite chronobiologists, here:
“The phase of an individual’s body clock in relationship to a zeitgeber is a biological phenomenon and not a matter of discipline.”Till Roenneberg
He basically says that it didn’t matter for me how much I wanted to sleep (“not a matter of discipline”). But that when I could fall asleep depended on my circadian rhythm (“individual’s body clock”) and the external stimuli (“zeitgeber”) I was exposed to.
And yes, also after my injury, I did want to continue my normal daily rhythm. But I missed natural light in the morning (the external stimuli aka zeitgeber) to do so. Something that changed again when I started my morning walks. And thereafter when I was able to run again in the mornings.
What can you take away from this? Now that you have seen above both how you can fall asleep earlier and how you can improve your sleep quality through aligning with your circadian rhythm, why not give it a try?
Try out the tips from above and have a look at what changes for you! And you will be surprised how much of a change there just might be.
There are three key takeaways that I want to share with you that all help you know if you have social jet lag and how to overcome it:
- The difference in your sleep pattern between your work (or school) days and your free days shows you how much you are affected by social jet lag. Calculate the average of your midsleep points for each of these. Your midsleep point is the middle point between when you fall asleep and when you wake up. The difference tells you how much you are affected by social jet lag.
- Social jet lag is the most frequent type of living against your circadian rhythm and the consequences lead to significantly worse health and wellbeing. Since social jet lag is chronic, you might already have learned to live with its consequences as normal. But now you know their connection and what you can do about it.
- There are four main ways to overcome social jet lag. These help you to fall asleep earlier at night, to improve your sleep quality, or to repay your sleep debt.
- Increase your natural light exposure as much as you can during the day.
- Reduce your artificial light exposure during the evening and at night.
- Don’t eat too late in the evening.
- Take a nap during the day if you can’t get enough sleep during the night.
And now back to you: How big is the difference between your midsleep points during the week and on the weekend (aka how much are you affected by social jet lag)? And which of these tips will help you most to overcome your social jet lag?
PS: If you found this information useful, spread the word and help those who would benefit most from it 🙂
- 1.Sűdy ÁR, Ella K, Bódizs R, Káldi K. Association of Social Jetlag With Sleep Quality and Autonomic Cardiac Control During Sleep in Young Healthy Men. Front Neurosci. September 2019. doi:10.3389/fnins.2019.00950
- 2.Roenneberg T. Internal Time. Harvard University Press; 2012.
- 3.Wittmann M, Dinich J, Merrow M, Roenneberg T. Social Jetlag: Misalignment of Biological and Social Time. Chronobiology International. January 2006:497-509. doi:10.1080/07420520500545979
- 4.Merrow M, Roenneberg T. Circadian clocks: how rhythms structure life. Presented at the: coursera; 2019; Ludwig-Maximilians-Universität München (LMU).
- 5.Roenneberg T, Allebrandt KV, Merrow M, Vetter C. Social Jetlag and Obesity. Current Biology. May 2012:939-943. doi:10.1016/j.cub.2012.03.038
- 6.Roenneberg T, Merrow M. Entrainment of the Human Circadian Clock. Cold Spring Harbor Symposia on Quantitative Biology. January 2007:293-299. doi:10.1101/sqb.2007.72.043
- 7.Roenneberg, Pilz, Zerbini, Winnebeck. Chronotype and Social Jetlag: A (Self-) Critical Review. Biology. July 2019:54. doi:10.3390/biology8030054
- 8.Pilz LK, Keller LK, Lenssen D, Roenneberg T. Time to rethink sleep quality: PSQI scores reflect sleep quality on workdays. Sleep. February 2018. doi:10.1093/sleep/zsy029
- 9.Grimaldi D, Carter JR, Van Cauter E, Leproult R. Adverse Impact of Sleep Restriction and Circadian Misalignment on Autonomic Function in Healthy Young Adults. Hypertension. July 2016:243-250. doi:10.1161/hypertensionaha.115.06847
- 10.Vetter C, Devore EE, Wegrzyn LR, et al. Association Between Rotating Night Shift Work and Risk of Coronary Heart Disease Among Women. JAMA. April 2016:1726. doi:10.1001/jama.2016.4454
- 11.Morris CJ, Purvis TE, Hu K, Scheer FAJL. Circadian misalignment increases cardiovascular disease risk factors in humans. Proc Natl Acad Sci USA. February 2016:E1402-E1411. doi:10.1073/pnas.1516953113
- 12.Knutsson A. Health disorders of shift workers. Occupational Medicine. March 2003:103-108. doi:10.1093/occmed/kqg048
- 13.Hulsegge G, Gupta N, Proper KI, et al. Shift work is associated with reduced heart rate variability among men but not women. International Journal of Cardiology. May 2018:109-114. doi:10.1016/j.ijcard.2018.01.089
- 14.Rutters F, Lemmens SG, Adam TC, et al. Is Social Jetlag Associated with an Adverse Endocrine, Behavioral, and Cardiovascular Risk Profile? J Biol Rhythms. September 2014:377-383. doi:10.1177/0748730414550199
- 15.Wong PM, Hasler BP, Kamarck TW, Muldoon MF, Manuck SB. Social Jetlag, Chronotype, and Cardiometabolic Risk. The Journal of Clinical Endocrinology & Metabolism. December 2015:4612-4620. doi:10.1210/jc.2015-2923
- 16.Parsons MJ, Moffitt TE, Gregory AM, et al. Social jetlag, obesity and metabolic disorder: investigation in a cohort study. Int J Obes. December 2014:842-848. doi:10.1038/ijo.2014.201
- 17.Koopman ADM, Rauh SP, van ‘t Riet E, et al. The Association between Social Jetlag, the Metabolic Syndrome, and Type 2 Diabetes Mellitus in the General Population: The New Hoorn Study. J Biol Rhythms. June 2017:359-368. doi:10.1177/0748730417713572
- 18.Levandovski R, Dantas G, Fernandes LC, et al. Depression Scores Associate With Chronotype and Social Jetlag in a Rural Population. Chronobiology International. September 2011:771-778. doi:10.3109/07420528.2011.602445
- 19.Panda S. The Circadian Code. Rodale Books; 2018.