Tuning Into Your Natural Rhythm
The circadian rhythm is one of my favorite topics to talk about. Is that kind of nerdy to say? Oh well. Our biological rhythms are fascinating because they are so intricate and complex, the result of dozens of bodily systems working together to create balance in our bodies.
I won’t bore you with the details about every facet of the circadian rhythm, but I will share how they impact some of the most important bodily functions, including sleep. Mostly, I want you to have this information because it can provide you with a greater sense of power and control over your body and sleep.
What is Our Natural Circadian Rhythm?
Your circadian rhythm is like a 24-hour internal clock that keeps your body on schedule. It helps regulate many different body systems, like sleep, hormones, digestion, body temperature, and the immune system.
The circadian rhythm is controlled mostly by the light/dark cycle of the earth. This helps to keep our bodies doing the same thing at the same time every day. Our bodies crave consistency like this, and it thrives when our behaviors align with the timing of these systems (for instance, when we eat at the time of day when our best digestion occurs).
What Does the Circadian Rhythm Do?
Short answer: it’s A LOT. I’ll try to keep this brief but just know that the circadian rhythm regulates almost every major bodily function. I’ll list a few of the most important:
1. The Sleep-Wake Cycle: our bodies function best when we sleep at night and are awake during the day. The circadian rhythm helps us to keep consolidated sleep at night (meaning that we sleep in one big interval) and remain awake all day long.
2. Hormone Regulation: many of our hormones function in a 24hr pattern, being higher at certain parts of the day than others. This includes hormones like melatonin (more on that later), cortisol (stress hormone), and insulin (important for digestion).
3. Metabolism & Digestion: we digest food most efficiently during the day. Remember that hormone insulin? It is released in the largest amounts during the day to support digestion. During the night, it backs way off because we tend not to eat much at night.
4. Cardiovascular Function: Did you know that your heart rate and blood pressure drop quite a bit during the night? This gives your cardiovascular system a chance to take a break before it ramps back up in the morning.
How does it work?
There is an area of your brain called the suprachiasmatic nucleus, which is a long, fancy word that you don’t have to remember. Instead, you can just think of this as the Master Clock. This part of your brain takes in information about the time of day and then sends out signals to the rest of the body to turn on/off certain functions.
Think of these inputs to the Master Clock as cues to synchronize the clock’s rhythm to the 24-hr cycle of the sun, keeping it from lagging behind.
There are a number of cues that the body uses (we call these Zeitgebers, which is another fancy word, this time German, for “time-giver”). Why should you care about this process? Well, knowing which inputs are going to help keep you in rhythm is essentially a playbook for how to feel good during the day and sleep well at night.
I’ll take a second to just talk about the 3 most important “time-givers”:
1. Bright Light: this is by far the most powerful cue for circadian alignment. When light enters into your eyes, it sends a message to the Master Clock that it’s daytime. The Master Clock then broadcasts alerting signals telling your body to stay awake. When our exposure to bright light decreases (i.e., when the sun goes down), the Master Clock signals the hormone melatonin to turn off all those alerting signals so that we can get some sleep.
2. Food & Meal Timing: while nowhere near as powerful at regulating the circadian rhythm as light exposure, the timing of when you eat sends signals to your brain via the gut. It tells the body when to turn on the process of digestion and the release of the relevant hormones, like insulin. The body’s natural rhythm is that digestion happens during the day and fasting occurs at night.
3. Physical Activity & Exercise: exercise and movement increases your core body temperature and the hormone cortisol. This increases alertness, essentially telling the body that it’s time to be awake.
How can I Support a Healthy Circadian Rhythm?
Well, you might have guessed this, but it’s all about timing, timing, timing! But don’t stress about this, because it’s not as complicated as it seems.
First, pay attention to your light exposure.
I think that most of us have heard that screen time at night is bad. And yes, blue light does suppress melatonin, making you feel more alert at night. But the flip side is also true, exposure to bright light during the day is vitally important. Most of us spend the vast majority of our day indoors. This is a problem because daylight provides us the best bang for our buck when it comes to feeling alert.
So I always tell people to prioritize time in the daylight. This can be tricky in winter, which is why so many people feel bad during the winter. At the very least, we should be turning on all lights and opening curtains during the day. I love sitting and working by a window for this reason. Bonus points for doing this earlier in the day, rather than later.
Additionally, once the sun goes down, be sure to turn the lights down as well. Try turning on lamps rather than overhead lights at home. While reducing screen time is always ideal, watching TV isn’t going to be enough to ruin your sleep. But staring at your phone while laying in bed might (for reasons beyond light exposure).
Next, keep a consistent eating schedule.
As I mentioned before, the hormones responsible for digestion peak during the day, supporting healthier digestive patterns. Eating during the night means the body has fewer available resources to process and make use of that energy, making it more likely to be stored as fat. This also disrupts sleep by signaling greater alertness.
We can support a healthier circadian rhythm by eating at regular times during the day. A regular pattern allows the body to predict when it will need to digest food and be prepared to turn on digestion. This reduces digestive problems and can actually reduce metabolic disorders like diabetes.
This also means that erratic meal timing—like skipping meals or eating late at night—can throw off your internal rhythm, much like jet lag does after a long flight. When your body doesn't know when to expect food, it can struggle to regulate hunger hormones, leading to cravings, energy crashes, and even disruptions in the quality of your sleep. By keeping a consistent eating schedule, you’re not just supporting digestion—you’re reinforcing your body's natural clock, making it easier to maintain steady energy levels, a healthy metabolism, and more restful sleep.
Finally, be thoughtful about activity levels.
Exercise that happens too close to bedtime (within a couple of hours) can trick the body into feeling more alert, making it difficult to fall asleep. Time your exercise to happen earlier in the day. Everyone is a little different in terms of their peak performance times, but some studies show that muscle strength and cardio efficiency is best in the afternoon.
But really, it’s about trial and error. Try workouts at different times of the day and see how you feel. You likely will notice that it’s easier to complete your workouts at certain times of the day. Go with that if you can! But the big caveat here is that any exercise is better than none, so if working out in the afternoon doesn’t work for you, don’t sweat it (no pun intended). Instead, the benefits will outweigh some minor performance deficits, unless you’re an Olympian or professional athlete.
In conclusion
Living your life in alignment with your circadian rhythm is always going to feel better than working against it. But that doesn’t have to mean being super rigid and overscheduling your life. Instead, think about doing wakeful activities, like getting outside, eating, and working out during the daylight hours. When the sun goes down, start thinking about promoting restfulness and relaxation while turning down the lights. It really is that simple!
And as always, if you need support with finding the rhythm that works best for you, we are here to help. Schedule a free 15-minute phone consultation if you have questions!
