Whether you’re looking to get more energy or fall asleep faster come bedtime, your circadian rhythm (or body clock) plays a part. When you work with it, everything from your energy to your sleep, your productivity to your mental and physical health are boosted.
But knowing the timing of your circadian rhythm isn’t exactly intuitive. Luckily, there are some tests you can do to find the timing of your circadian rhythm, so you can get the most out of it.
Below, we’ll dive into what your circadian rhythm is and how you can use the RISE app to test for it and improve your health, well-being, sleep, and energy.
While you’re sleeping, working, and living your life, there’s a biological clock ticking away inside of you. This is your circadian rhythm.
This internal clock runs on a roughly 24-hour cycle and dictates your sleep-wake cycle, the production of certain hormones, and body temperature and blood pressure fluctuations, amongst many other things.
But there’s more than one circadian clock to think about. We all have one master clock in our brains. This is called the suprachiasmatic nucleus (SCN). It’s found in a part of the brain called the hypothalamus and it runs the show as the central pacemaker.
Beyond the SCN, there are clocks in almost every tissue and organ system in your body — including in your gut, immune system, and liver. These are called peripheral clocks.
The SCN is attuned to the light-dark cycle of the outside world, and it communicates with peripheral clocks around your body. All of these circadian rhythms work together to tell your body the best time to eat, sleep, be alert, and so on.
Your circadian rhythm isn’t set in stone, though. It receives signals from the outside world — also known as zeitgebers (German for time givers) — which act as a cue telling your clock what time it is.
When you get light exposure, eat, or exercise, you can either reinforce your circadian rhythm (i.e. confirm it’s running at the right time) or you can make it shift earlier or later.
This process is called entrainment, which simply means the setting or resetting of your circadian rhythm.
Another key term to be aware of is the phase-response curve (PRC). This is the relationship between a zeitgeber and the response it causes. In simple terms, there’s a time of day when a zeitgeber switches from shifting your circadian rhythm earlier to pushing it back.
For example, when you get morning sunlight, you’re telling your circadian rhythm it’s daytime and time to be awake and alert. When you get bright light in the evening, however, you can push back your circadian rhythm, making it harder to fall asleep.
Your circadian rhythms can run out of sync with your day-to-day activities, too. When you’re living out of sync — perhaps by sleeping at irregular times or working night shifts — you can experience poor sleep, low energy, and an increased risk of everything from obesity to depression, heart disease to cancer.
You could probably make a good guess at whether you’re more of an early bird or night owl. These are chronotypes, or a natural tendency to go to sleep, wake up, and be alert earlier or later in the day.
If you’re an early chronotype (also known as morning type, early bird, or lark), your circadian rhythm will skew earlier. Everything — including your sleep-wake cycle — will happen earlier in the 24-hour cycle.
If you’re an evening chronotype (also known as evening type or night owl) it’s the opposite. Your circadian rhythm will skew later, and your sleep-wake cycle will be later in the 24-hour cycle.
While your chronotype is determined by factors like age and genetics, you can still shift the timing of your circadian rhythm. For example, one study found when night owls were exposed to natural light only for a full week — no artificial light or screens — their circadian rhythms shifted earlier in the day to look more like those of early birds.
Research suggests about 40% of us are either morning or evening chronotypes, while the rest of the population sits somewhere in between. Not sure where you sit? We’ve covered how to find out your chronotype here.
It may sound complicated, but there are natural rhythms in other areas of life:
Apart from being a fun experiment, there are many benefits to doing a circadian rhythm test.
Here’s what you can do when you know your circadian timing:
Beyond your circadian rhythm, RISE can work out your unique sleep need, so you know what you should be aiming for each night.
RISE users on iOS 1.202 and above can click here to view their sleep need.
Want to find out the timing of your circadian rhythm? There are a few ways you can test for it.
One way to test for your circadian rhythm is to keep a sleep and energy log for a minimum of seven days, ideally 14 days.
Clinicians often use sleep logs to diagnose circadian rhythm sleep-wake disorders (CRSWD). But you can use this method yourself at home.
Try going a week or two without an alarm and make a note of your natural sleep and wake times. Then, during the day, make a note of when you feel most alert and focused, and when you feel your energy is lower.
This method can give you an idea of your chronotype and the rough timings of your circadian rhythm.
But there are a few problems with this method, including:
There are plenty of online quizzes and surveys out there promising to tell you the timing of your circadian rhythm in just a few clicks.
This method is similar to keeping your own sleep log. You’ll probably be asked about your sleep times, when you feel most alert, and the times you do certain activities on your days off.
There are also more official surveys that are often used in scientific research. These include:
These questionnaires and online quizzes don’t measure circadian rhythms exactly, but they can give you an indication of whether yours naturally skews earlier or later.
These methods have many of the same problems that keeping your own sleep log does, including:
You can check into a lab and get scientific measurements of your circadian rhythm. This method involves checking for markers of your circadian rhythm such as your:
There’s also a blood test that can measure your circadian rhythm from biomarkers from a blood draw, but this isn’t widely available yet.
There are a few problems with getting a circadian rhythm test in a lab, too.
Most of us can’t (or simply don’t want to) check into a lab, and surveys and online quizzes aren’t a reliable way of testing your circadian rhythm. This is where the RISE app comes in as a test for your circadian rhythm.
It’s quick, easy, reliable, and you’ll get practical information you can use to improve your sleep, energy levels, and overall wellness. No blood draws needed, just a smartphone.
Another plus? You’ll also be one step ahead of your circadian rhythm as you’ll see a prediction of what it’ll look like each day. This will help you plan your day effectively and stay in sync to boost your energy levels, sleep, and productivity (more on how to do all that soon).
RISE users on iOS 1.202 and above can click here to see their circadian rhythm on the Energy screen.
RISE uses your inferred light exposure, recent sleep times, and science-backed algorithms to predict the timing of your circadian rhythm.
Our prediction model is built on the SAFTE model (which stands for sleep activity, fatigue, and task effectiveness). This model was developed by the US Department of Transportation and the Department of Defense, and it predicts changes in cognitive performance based on your circadian rhythm.
RISE does all the complicated science in the background, but you’ll get a simple visual of your circadian rhythm. You’ll see how your energy fluctuates over the day, including when your body wants to wake up, wind down for bed, and sleep.
Speaking of sleep, RISE also shows you your Melatonin Window. This is what we call the roughly one-hour window of time when your body’s rate of melatonin is at its highest. Melatonin is the hormone that primes your body for sleep, so your Melatonin Window is essentially your ideal biological bedtime. If you go to bed during this one-hour window, you should find it easier to fall and stay asleep.
How do we work out this window? We use the St Hilaire mathematical model of core body temperature, inferred light exposure, and sleep times to calculate your DLMO. Then, we add 1.55 hours to this — as research suggests the ideal bedtime is about two hours after your DLMO — and add and subtract 30 minutes from this time to get your ideal one-hour bedtime window.
RISE users on iOS 1.202 and above can click here to set up a reminder to check their Melatonin Window.
Your circadian rhythm is constantly running in the background of your life, but you can get out of sync with it (also known as circadian misalignment).
You might be out of sync with your circadian rhythm if:
When your circadian rhythm is disrupted, you may find it harder to fall asleep at night, struggle with daytime sleepiness, have lower focus during the day, and you’ll be damaging your health, too.
You can reset your circadian rhythm, though, shifting it to suit the timings of your daily life. Here’s how:
And we’ve shared advice for specific situations, including:
Your circadian rhythm can get thrown off by your sleep or work times, but a disorder may also be to blame. Some of these disorders are caused by your sleep and work, too.
Circadian rhythm disorders include:
Speak to a doctor if you think you have a circadian rhythm disorder. They may be able to recommend behavioral changes and treatment options, like melatonin supplements and light therapy.
Once you know your circadian rhythm, and have perhaps reset it to suit your lifestyle, it’s time to keep it on track. This will ensure you’re taking the best care of your health, and it’ll help you enjoy better sleep and more energy.
Here’s what to do:
For a final piece of advice, we turned to our sleep advisor and medical reviewer, Dr. Chester Wu. Here’s what he had to say about how best to keep your circadian rhythm in check.
“My key piece of advice for keeping your circadian rhythm in check is to think about light. Try to get out in natural sunlight each morning and make your nights as dark as possible. This will signal to your circadian rhythm when it’s time to be awake, and when it’s time to sleep.” Rise Science Medical Advisor Dr. Chester Wu
RISE users on iOS 1.202 and above can click here to set up their 20+ in-app habit notifications.
By testing your circadian rhythm and finding out the timing of it, you can work to sync it up to your daily life. This will help you fall asleep at bedtime, meet your sleep need, enjoy more energy each day, be more productive, and reduce your risk of a whole host of physical and mental health conditions.
The RISE app is a circadian rhythm test in your pocket. It uses algorithms plus location and sleep data to predict your circadian rhythm each day. RISE can also guide you through 20+ sleep hygiene habits to help you get a good night’s sleep and keep your circadian rhythm on track.
Test your circadian rhythm with the RISE app. RISE can tell you when your body naturally wants to wake up, wind down for bed, and go to sleep. You’ll also see when you’ll most likely be most alert and when your energy will naturally dip during the day.
No, everyone’s circadian rhythm is not the same. Some of us are naturally early birds with a circadian rhythm that runs earlier in the day, and some of us are natural night owls with a rhythm running later in the day. Light, meals, and exercise timing can also shift your circadian rhythm.
Yes, circadian rhythms change with age. Our circadian rhythm flattens as we age, meaning the signals for when to wake up and go to sleep are weaker. Your circadian rhythm shifts earlier as you age, meaning you naturally want to wake up and go to sleep earlier.
If your circadian rhythm is off, you may have trouble falling and staying asleep at night and have low energy and focus during the day.
You may have a circadian rhythm disorder if your sleep cycle is broken, or runs about two hours earlier or later than what’s considered normal. You may also experience symptoms like poor sleep, low energy, and trouble focusing.
You can reset your circadian rhythm by getting bright light exposure first thing in the morning. This will tell your circadian rhythm it’s time to be awake and alert. If you want to move the timing of your circadian rhythm, try shifting your sleep and meal times by 15 to 30 minutes each day. Do this in the direction you want to move your circadian rhythm.
RISE makes it easy to improve your sleep and daily energy to reach your potential
RISE makes it easy to improve your sleep and daily energy to reach your potential