Ok, the general answer to how long it takes to fix your circadian rhythm is: It depends. And I will show you what it depends on and how long it will take you in your individual situation. The biggest factor is whether you want to fix the circadian rhythm of your everyday life or after traveling time zones (aka jet lag). And then it depends on how strong you make your environmental cues to help your body fix your circadian rhythm.
Case I: How long does it take to fix your circadian rhythm in your everyday life?
|Time to fix your everyday circadian rhythm||Advancement of your circadian rhythm|
|Two hours of natural light exposure||About 1 hour|
|One weekend in nature||About 1.4 hours|
|One week in nature||About 2 hours|
Case II: How long does it take to adjust your circadian rhythm after crossing time zones (aka jet lag)?
|If you fly east||If you fly west|
|Time fix your circadian rhythm after crossing time zones||~90 minutes/ day||~120 – 140 minutes/ day|
Read on to get a full understanding of:
- Why you need to fix your circadian rhythm in the first place
- How long it takes to fix your circadian rhythm for your everyday life
- How long it takes to fix your circadian rhythm if you experience jet lag
- What you can do to fix your circadian rhythm faster
- My personal experiences and your key takeaways
Now, let’s start with an overview of why you need to fix your circadian rhythm in the first place. No matter which of these two cases you belong to. This will help you to see which factors you might want to change and how these impact how long it takes to fix your individual circadian rhythm.
Why You Need to Fix It
Why Do You Need to Fix Your Circadian Rhythm in the First Place
First off, why would you need to fix your circadian rhythm? Because it is not aligned with your external day! One way or another (more about that later).
Here’s the thing. Your circadian rhythm is your body’s way to optimize the timing of all your internal functions. Like your sleep-wake cycle, your hormone levels, your core body temperature, your physical and cognitive performance, or even your immune system.
Now, you have a part in your brain (called the SCN) that works as your central internal clock. And your circadian rhythm optimizes the timing of all your body functions based on this internal clock.
And when do you need to fix your circadian rhythm? Correct! When your internal clock thinks that it’s a different time than your external time (the time on your watch) shows.
Wait… But how could your internal clock even know what time it is? Based on two pieces of information:
- Your internal clock has its own cycle of roughly twenty-four hours.
- Your internal clock adapts its cycle through light information to match your exactly twenty-four-hours long external day. Yes, it uses your light exposure as information about the time of day.
Ok, basics covered. Now it’s time to have a look at the two reasons why you need to fix your circadian rhythm:
- Your everyday life: Your internal clock is off because you don’t get the right daily light exposure.
- Your jet lag: You traveled across time zones and need to align your internal clock again.
At first sight, those are two very different cases. The chronic everyday life situation vs the temporary jet lag situation.
But what they both have in common is the misalignment of your circadian rhythm (based on your internal clock). And that you can align both your internal clock and your circadian rhythm through using environmental cues (called zeitgebers) as information about the time of day.
And what are those external zeitgebers? You guessed correctly! The by far most important one is light. Your daily light exposure. And both the intensity and timing of your light exposure determine how long it takes for you to fix your circadian rhythm.
So, with that in mind, let’s have a look at those two cases now. First your everyday life and then jet lag.
Your Everyday Life
Case I: How Long Does It Take to Fix Your Everyday Life
I’ve mentioned above that you need to fix your circadian rhythm because your internal clock doesn’t have the correct time of day. And that this is because of your daily light exposure.
With our modern lifestyles, we spend too much time indoors and not enough outdoors. Want to have some numbers behind? Sure!
- One study found that we spend an average of 87% of our time in buildings and an additional 6% of our time in vehicles.1
- And another study found that we spend less than one hour outdoors during the week and less than three hours outdoors on weekends.2
Now, your circadian rhythm needs your light exposure as a zeitgeber (an environmental cue) to align to your time of day. And what light intensities does it expect? Right, those of the sun. But with too much time inside and not enough time outside you shield yourself from that.
Here is what Till Roenneberg, one of the leading chronobiologists of our time, states about how much shield yourself from your zeitgeber light:3
“People in industrialized settings are exposed to zeitgebers about 200 times weaker than those synchronizing the clocks of people who work outdoors.”Till Roenneberg
And even worse, you also add artificial light in the evening and at night that further confuses your circadian rhythm.
Here are the two problems why you need to fix your circadian rhythm:4
- You don’t get enough (natural) light during the day
- You get too much (artificial) light during the evening and night
Ok, let’s quickly sum it up again. You spend way too much time inside and not enough time outside. As a result, you only get a fraction of the light you need during the day. But in the evening and at night, you get way too much light.
How does that impact your circadian rhythm? Let me put that into the words from Ellen Stothard, from the University of Boulder, Colorado, and colleagues:5
“Reduced exposure to daytime sunlight and increased exposure to electrical lighting at night leads to late circadian and sleep timing.”Ellen Stothard et al.
Now, what do you think you need to do to fix your circadian rhythm? Yes, you need to fix those two problems connected to your light exposure. And how you do that determines how long it takes.
Let’s have a look at the following three studies about natural light exposure to help you determine how long it will take for you to fix your circadian rhythm:
|Time to fix your circadian rhythm||Advancement of your circadian rhythm|
|Two hours of natural light exposure6||About 1 hour|
|One weekend in nature5||About 1.4 hours|
|One week in nature7||About 2 hours|
There are two things you can see here. One, already two hours of natural light exposure goes a long way in fixing your circadian rhythm. And two, to fix your circadian rhythm, you need to advance it. You can measure this advancement in hours. And the more natural light (your zeitgeber) you get the more your circadian rhythm advances.
Let’s have a look at these three studied cases and how you can use them to your advantage.
Want to get all the practical tips on how you can fix your circadian rhythm? Check them out in this post: “Get Your Circadian Rhythm Back on Track: The Ultimate Guide”
Get Two Hours of Natural Light Exposure
For their seminal paper called “Entrainment of the Human Circadian Clock,” leading chronobiologists Till Roenneberg and Martha Merrow studied more than 60,000 people and their light exposure.6
What do you guess they found out about the light exposure of their participants? Yes, that they only receive a fraction of the natural sunlight that they’d need. But what’s more? This shifted their whole circadian rhythm (measured by their sleep-wake-cycle, called chronotype) later. And everything that is connected with it.
And here comes the interesting part: If those participants spent two hours outside, then their circadian rhythm advanced by one hour, closer to “normal.” (Or better, it was delayed by one less hour.)
What can you take away from that? Yes, spend two hours outside every day! You most likely receive only a fraction of the sunlight your body needs to set yourself up for a strong circadian rhythm that is aligned with your day. Plus, you receive too much artificial light at night. But with only two hours of sunlight, you can bring your body one hour closer to your true circadian rhythm.
Does that already fix your circadian rhythm? If your circadian rhythm is only misaligned by one hour then yes. Otherwise not.
To find out how misaligned your circadian rhythm is, you can compare your sleep-wake patterns during the week with those at the weekend. If the difference is too big when you go to bed and when you wake up, then you experience something called social jet lag. You can read all about it here: “What Is Social Jet Lag and How to Overcome It”
Can you fix your circadian rhythm even more if you spend more than two hours outside? Well, yes and no. Roenneberg and Merrow found that your circadian rhythm (again, measured by your chronotype) changes very little beyond those two hours. At least during one day.
But what about not just receiving a few hours of sunlight a day, but spending a weekend in nature? Yes, that helps you to fix your circadian rhythm even more. So let’s have a look at that next.
Spend a Weekend in Nature
Ellen Stothard and Kenneth Wright, from the University of Boulder, Colorado, and colleagues had a look at what happens to the timing of your circadian rhythm if you spend one weekend in nature.5
In their studies, they sent a group of participants camping in nature. For one full weekend. That means that their participants didn’t “only” receive two hours of natural sun exposure, but two full days (plus campfires). And they also didn’t use any artificial light or electronic devices in the evening.
The result? Their circadian rhythms advanced by 1.4 hours on average.
Would you also have the potential to advance your circadian rhythm by that much? Most likely yes. And as a result, also your sleep-wake cycle and all your body functions would be better aligned to your local time. Or, to put it differently, they would be about 1.4 hours less misaligned.
Now, if one weekend full of only natural light exposure advances your chronotype that much, doesn’t that make you wonder something about your everyday life? I mean, in terms of how much more potential there is for you just by leveraging your light exposure.
But there’s even more to that story! Let’s have a look at what happens to your circadian rhythm if you were to spend one full week in nature.
Spend a Full Week in Nature
Well, you’ve seen that you can fix your circadian rhythm by one hour in a day and by one-point-four hours on a weekend. But what happens when you spend a full week in nature?
Kenneth Wright, from the University of Boulder, Colorado, and colleagues tested out exactly that. They sent volunteers camping for one week. Again, only with natural light (like sunlight or campfires) and without any artificial light or electronic devices. And the volunteers were also able to self-select their sleep schedules during that time.7
What happened? After this one week in nature, all measured markers of the volunteers’ circadian rhythm advanced on average by two hours. Two full hours!
In addition, they found that the beginning of the internal biological night of those volunteers started at sunset. And that their internal biological night ended just after sunrise.
Here’s what Kenneth Wright and colleagues stated to summarize this study:7
“Modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks.”Kenneth Wright et al.
Just imagine you’d get all the natural light exposure your body has developed for. And you live aligned with your circadian rhythm. That would allow you to wake up and fall asleep about two full hours earlier.
Plus, it would also come with all the other benefits of a strong circadian rhythm, like improved sleep quality, higher daily energy levels, or a stronger immune system, to name a few.
You can read more about the benefits of living aligned with your circadian rhythm in this post: “Why Is the Circadian Rhythm so Important for You”
Fully Fix Your Circadian Rhythm
Now, it is a great start if you get two hours of sunlight a day. And it is even better if you are spending more time in nature with only natural light exposure. But that might not always be practical or fit your lifestyle.
I wrote a dedicated post about “Get Your Circadian Rhythm Back on Track: The Ultimate Guide” to cover this topic in detail.
And here’s the summary for you. Let’s start with light, the by far most important zeitgeber (environmental cue) for your circadian rhythm:
Problem 1: You don’t get enough light during the day
Tip #1 Spend at least two hours outdoors during the first half of every day
Tip #2 Stay as close to windows as possible if you are indoors
Tip #3 Take artificial light showers during the day if needed
Tip #4 Don’t wear sunglasses (if you don’t spend the whole day outside)
Tip #5 Spend a weekend in nature
Problem 2 & 3: You get too much light & blue light during the evening and night
Tip #6 Adapt your home lighting for the second part of the day
Tip #7 Reduce blue-light emissions from your screens
Tip #8 Use blue-light filtering eyeglasses
Tip #9 Avoid any (blue) lights at night
But then, there are also two more zeitgebers (environmental cues) for your two other core circadian rhythms. Those are food for the circadian rhythm of your organs and exercise for the circadian rhythm of your muscles and tissues (check out: “How Many Circadian Rhythms Do We Have” for more information).
Problem 4: You eat for too long and/ or too late
Tip #10 Stop eating early enough in the evening
Tip #11 Eat for fewer hours every day
Bonus “Problem”: You don’t exercise at the right times
Tip #12 Use exercise to help align your circadian rhythm
Again, you can read all about it in “Get Your Circadian Rhythm Back on Track: The Ultimate Guide.”
Case II: How Long Does It Take to Fix Your Jet Lag
How long does it take to fix your circadian rhythm after traveling across time zones? Well, it depends. Again. But this time it depends on different factors. Namely if you fly east or west. And how many time zones you cross.8,9
And to align your circadian rhythm to your new time zone, you need strong zeitgeber (environmental cues) again. Just as when you align your circadian rhythm to your local time zone.
Let’s take it from Till Roenneberg, one of our leading chronobiologists, again:3
“The stronger you can make the new zeitgeber, the faster your body clock will arrive at the new destination.”Till Roenneberg
In short, your circadian rhythm needs to speed up when you fly east. And it needs to slow down when you fly west. And, on average, your circadian rhythm adapts much faster when it needs to slow down (for longer days, flying west) than when it needs to speed up (for shorter days, flying east).9
So, with that in mind, how long does it take to fix your circadian rhythm after you fly east or west?
|If you fly east||If you fly west|
|Time to fix your circadian rhythm10,11||~90 minutes/ day||~120 – 140 minutes/ day|
Just to be clear, those numbers reflect the time it takes if you use your light exposure – your by far most important zeitgeber – to your advantage once you arrived at a new local time zone.
But there’s more to it if you want to fix your circadian rhythm much faster. And beat jet lag.
- Light is your most important zeitgeber: Adapt your light exposure already before your travels. Maximize your light exposure in the morning if you travel east and in the evening if you travel west. And even more so once you’ve arrived.
- Food is your second-most important zeitgeber: Stop eating slightly earlier (east) or start eating slightly later (west) before you travel. And then only eat during local eating times once you’ve arrived.
- Exercise can also help you as a distant third-most important zeitgeber: Exercise either in the morning/ early afternoon (east) or in the evening (west).
Ok, that was just a high-level summary. But there’s more to it. Much more.
Check out the full story here: “Use Your Circadian Rhythm to Beat Jet Lag: The Ultimate Guide”
What Can You Do to Fix Your Circadian Rhythm Faster
Are there any magic pills to fix your circadian rhythm quicker? Well, not really. Unless you consider your zeitgebers magic pills!
And those zeitgebers (remember, the environmental cues that align your circadian rhythm) are the way to fix your circadian rhythm. Now, the stronger you make those zeitgebers, the more impactful they are. And if you use them at the right time, then they will also help you to fix your circadian rhythms!
Let me quickly recap here: You have three core circadian rhythms that you need to align with your local time. And the by far most important one is your central (master) circadian rhythm that has your light exposure as your zeitgeber. This one also coordinates and orchestrates all your other circadian rhythms.12
If you’d only care about one circadian rhythm, then it would be this one. Your central (master) circadian rhythm.
However, also the circadian rhythm of your organs is crucial. And that has your eating timings as its zeitgeber. When you start to consume your first calories (yes, also drinks and small snacks count), your organs need to start working on your digestion. And only about two-to-three hours after you stop consuming calories, they can work on repairing and rejuvenating themselves. A vital phase for your health.
Finally, there is the circadian rhythm of your muscles and tissues that has your exercise and activity levels as its zeitgeber.
|Core circadian rhythm||Zeitgeber (environmental cue)|
|Central (master) circadian rhythm||Light exposure|
|Circadian rhythm of your organs||Eating timings|
|Circadian rhythm of your muscles and tissues||Exercise and activity|
Actually, there are even more circadian rhythms that your central (master) circadian rhythm orchestrates. And even virtually every single has its own one. But normally you wouldn’t know because they are all aligned. Check out this post “How Many Circadian Rhythms Do We Have” if you want to find out more.
Now, in an ideal world, you’d already live aligned with all your circadian rhythms. But we don’t live in an ideal world.
So, what should you do? Yes, use the three zeitgebers of your core circadian rhythms to fix these! Check out those two full guides that I wrote to help you do exactly that:
- For your everyday life: “Get Your Circadian Rhythm Back on Track: The Ultimate Guide”
- For jet lag: “Use Your Circadian Rhythm to Beat Jet Lag: The Ultimate Guide”
Now, with that being said, let me give you some examples of my personal experiences.
My Personal Experiences
You have seen that your light exposure is by far the most important zeitgeber to fix your circadian rhythm. And I’ve also experienced the direct benefits of this.
My everyday life: I love to do sports and I love to do so outdoors. Like a full day of trail running or cycling around the mountains. And what I always notice at the end of the day is how much earlier I feel ready to sleep and how much more refreshed I wake up the next day.
Now, I know that exercise helps to improve my sleep quality. And I also try to implement as many “hacks” as possible to live aligned with my circadian rhythm. But the amount of positive change after one full day outside is still something that always amazes me.
My non-jet-lag: Similarly, I’ve been lucky to implement strong zeitgebers to combat any jet lag. I never had any issues flying west, but flying east used to be a problem. Well, until I used the zeitgebers of my three core circadian rhythms to my advantage.
Let me share a recent example with you about when I flew to Iten, Kenya for professional running training. I crossed one time zone to the east and I was also getting up about three hours earlier every day than back home. So, all in all, I had to shift my circadian rhythm by about four hours.
Now, did I have any issues with jet lag? Nope, luckily not. And here’s why:
- Light exposure, the zeitgeber of my central circadian rhythm: I was running every morning, starting around 6 am, just when the sun came out. One hour of full natural light exposure. I also stayed outside most of the day and was tired and spent once it got dark. That dramatically cut down my artificial light exposure in the evening and at night.
- Eating timings, the zeitgeber of the circadian rhythm of my organs: In Iten, I stayed with a local family and also ate together with them. That doesn’t just mean that I was able to eat delicious local food, but also that I was eating at local times. Besides breakfast, I skipped those.
- Exercise, the zeitgeber of the circadian rhythm of my muscles and tissues: Oh yeah, that’s what I was actually there for. I ran every morning. And mostly did a cycling or swimming session in the afternoon. If not another run.
My big takeaway is how much better I feel, when I have strong zeitgebers that align my circadian rhythm(s). Every day. And once I’ve felt the differences I know that I don’t want to have it anyhow else ever again.
Finally, there are five key takeaways that I want to share with you to help you fix your circadian rhythm:
- You need to fix your circadian rhythm because it is not aligned with your external day – the local time zone you are in.
- Case I, your everyday life: Your internal clock is off because you don’t get the right daily light exposure.
- After two hours of natural light exposure, you can fix your circadian rhythm by 1 hour
- After one weekend in nature, you can fix your circadian rhythm by 1.4 hours
- After one week in nature, you can fix your circadian rhythm by 2 hours
- Case II, your jet lag: You traveled across time zones and need to align your internal clock again.
- If you fly east, then you can fix your circadian rhythm by about 90 minutes per day
- If you fly west, then you can fix your circadian rhythm by about 120 – 140 minutes per day
- You can fully fix your circadian rhythm if you fully leverage the zeitgebers (environmental cues) of your three core circadian rhythms
- Your light exposure is the zeitgeber of your central (master) circadian rhythm.
- Your eating timings are the zeitgeber of the circadian rhythm of your organs.
- Your exercise and activity are the zeitgebers of the circadian rhythm of your muscles and tissues.
- How fast you fix your circadian rhythm depends on how strong you make your zeitgebers.
And now back to you: Do you feel like you need to fix your circadian rhythm? And what would you concretely do to fix it? Now, compare how you feel before and after you’ve fixed your circadian rhythm. And then take notice of how much better you feel afterward.
PS: If you found this information useful, spread the word and help those who would benefit most from it 🙂
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