Circadian rhythm – how your light environment impacts your health

Circadian rhythm is our 24 hour biological clock influenced by several factors of our daily routines. Humans are diurnal, the opposite of nocturnal, creatures. We function best when awake in the day and asleep in the night. Learning how to align your body with it’s circadian rhythm can improve sleep, mood, cognitive function and even aid in healing several types of hormone-related issues. Coincidentally enough, circadian rhythm regulation is also a way of ancestral living, an ancient approach to optimal health. Read below on how & why to support your daily circadian rhythm.

How to support your circadian rhythm

Circadian Rhythm tip #1: Be aware of your light environment.

Morning light

Going outside in the morning hours can be a simple way to reset your body’s biological clock. Morning light specifically signals to your body it’s the beginning of the day, immediately synchronizing your body’s clock to the time. Several studies show that when you get morning light, your brain stops making melatonin and starts producing cortisol. These are two things that should happen in the morning after a good night’s sleep. In fact, when morning light causes the melatonin production to stop, your circadian clock will instruct the body to begin melatonin production again 14 hours later. Not only does morning light allow the body to have the proper hormone production to wake, it also sets it up later for better sleep.

Morning light also has an “antidepressant” effect on the body. It has a direct effect on serotonin production, also known as the feel good hormone. Coupling serotonin production and proper melatonin production allows for both better sleep and a stable mood. Boosting your serotonin in the morning can have a positive effect throughout the rest of your day.

While viewing the sunrise may be a more ancestral approach, morning light in general is all good. Whether you’re an early riser or tend to sleep in, you can benefit from morning light regardless. After sunrise up until about 10am provides the rays you need that aren’t as direct as bright daylight. Whether 6am or 10am, you are able to signal the body that it’s morning and get the hormonal benefits.

Mid-day light

Mid-day rest & sunlight are also important for balanced sleep/wake hormone cycles. In the afternoon, there is a short burst of melatonin production. Maybe you’re familiar with what many deem the afternoon crash. While it isn’t good to feel debilitating fatigue, it’s normal to be a bit tired in the late hours of the afternoon. A short nap or rest from work can help with this, and so can afternoon light! Going outside to signal to your body the time of day is not only good in the morning, but also in the afternoon. You can keep the hormone production and circadian clock stable with allowing your body even just 10 minutes of afternoon sunlight. A perfect afternoon routine could be a short 15 minute nap followed by 15 minutes of sunshine rays.

Sunset

Viewing sunset is another way to sync your internal clock with the day. While both morning and afternoon sunlight will help produce evening melatonin, a walk at sunset or open shutters as the light dims down can support this even more. The colors produced at sunset are conveniently warm and calming. In fact, red light is produced at sunset, ultimately signaling the end of the day. Red light is the lowest on the spectrum and the lightest on the eyes. The body can easily produce melatonin and calm down when surrounded by red light (which we will talk more about here shortly).

Screen time & artificial light

As important as daily sunlight is, it’s also critical to consider the large impact of screens and artificial light. Screen technology emits blue light, which mimics the bright light produced by the sun in the afternoon. While this may not be a bad thing in the actual afternoon, screens are usually the first and last thing many of us look at, sometimes without even viewing natural outdoor light. This has a direct effect on circadian rhythm.

In fact, several studies suggest late night smartphone use may delay sleep onset, cause sleeping problems, lower sleep quality and even shorten sleep duration. Consequently, smart phone use in the morning can signal to the body it is already the afternoon, throwing off hormone production and the body’s circadian timing. No wonder sleep is affected!

Overhead lights are another factor commonly overlooked. Your basic light bulb actually emits blue light. Maybe not as much as looking directly at a cell phone screen, but nonetheless, some. Opening the blinds in the morning and evening hours around sunrise and sunset may be a better option than immediately flicking all the lights on. Using candles and red light bulbs in the evening are also great options.

Here’s a common scenario for someone working from home; wake, turn the lights on, check emails on the phone, open the laptop to start work, continue all day until near sunset, eat dinner and then wind down by scrolling the phone or watching a movie. This day is centered around screens and there is little to no break in blue light or time outside. In history, this has never been the case. This is not optimal for our circadian rhythm and therefore not optimal for our health.

Avoiding the sun and running on blue light from technology will keep you out of balance. Even just a few minutes of morning, afternoon, and evening sunlight can boost health for the majority of people. Try to be aware of how much you’re staring at a screen. A small effort to stop dependence on fake light is a big step in the right direction.

Red light therapy

As mentioned above, red light is a great addition as it’s the lowest frequency on the light spectrum. Red light therapy devices, all the way from infrared technology to the cheap red light bulb from your local department store, mimic the light at sunset. This stimulates melatonin production, and therefore, sleep quality. Infrared light therapy devices are also known to help with skin health, muscle growth, joint pain and all in all reduced signs of aging. It is restorative at a mitochondrial level, and may be worth the investment. However, if you’re just looking to create a wind-down friendly environment, switching your light bulb to a red colored one can do the trick.

Exposure to the outdoors & sun

Exposing yourself to the outdoors as much as possible is your best bet. No, this doesn’t mean directly sitting in sunlight all day. It can be things as simple as a few 5 minute sun breaks, opening your blinds, driving with your windows down, or even just sitting by an open window can all assist in your daily circadian health.

Take note that going outside even during cloudy, gloomy or rainy days still supports your biological clock. It doesn’t have to be sunny to get light in your eyes. While it might be less convenient, it’s still effective.

Circadian Rhythm tip #2: Appropriate meal timing

Eat upon waking

We’ve all heard that breakfast is the most important meal of the day. Food, especially breakfast, is another way to sync with your circadian clock. When you sleep, you inherently are fasting for several hours. When your body is in a fasting state, you can easily modify your circadian rhythm, even completely reset it. Simulating digestion within an hour of waking can signal to the body it’s the beginning of the day.

As mentioned above, cortisol and melatonin are two main players, not only affected by light but also food intake. When you eat in the morning, your cortisol rises. This stimulates your metabolism and allows for immediate energy production for the day. Keep in mind, this cortisol is positive. It offsets the melatonin and allows for peak energy in the morning, slowly dropping and increasing melatonin throughout the day for the eventual night.

Sunlight and food within the first hour of waking is the best way to begin your day and honor your biological clock. Light in the eyes and a nutritionally dense breakfast in the belly are guaranteed to support both your day and your health.

Avoid eating directly before sleep

While eating in the morning increases cortisol and decreases melatonin, the avoidance of eating in the late hours can do the opposite. The process of digestion recruits several bodily functions, ultimately keeping the body at work to break down food. Having a light dinner & doing so 1-2 hours before your evening wind down can also be a simple way of supporting circadian rhythm. This leaves time for the body to do what it needs to do before sleep, and be ready to fully wind down in the night.

Eat seasonal

While eating seasonal has several nutritional benefits, it can also be a way of signaling to the body not only the time of day but the time of year. This study shows that “melatonin production shows a seasonal variation relative to the ability of light.” As the seasons change, so does the length of daylight. Eating foods that are in season can cue the length of light & night to the body. This ultimately allows circadian rhythm alignment even with the changing times of sunrise and sunset.

Consider your caffeine intake

Caffeine intake can also affect your sleep/wake cycles, and therefore, your circadian rhythm. Caffeine can stay active in the body for up to 10 hours. Because of the way it affects the brain, it also can easily cause a significant afternoon crash. Both the lack of sleep and caffeine crash can be avoided with proper use. Delaying your coffee to after your breakfast (or even more, 90-120 minutes after waking), avoiding caffeine intake in the late afternoon hours, and keeping your total intake under 300 milligrams are all ways to include caffeine without hurting your biological clock.

Circadian Rhythm tip #3: Support your sleep.

Put the phone away.

Relax when it’s time to relax. Sure, scrolling your phone can feel like a mindless way to temporarily clock out of real life and enjoy yourself. However, it can also be extremely stimulating and emits a lot of artificial blue light. This not only keeps the mind constantly stimulated, but also signals to your body that it’s daytime. Both things can throw your circadian rhythm out of balance, especially if done in the late night hours.

Blue blocking glasses may be a good option if you have no choice but to work on a screen after sunset. They’ve become super trendy with the rise of working from home and/or on a screen, however, it’s important to invest in a quality pair if they will have any effect. Feel free to do some research and make sure you read the reviews before buying. Two brands I know and trust are Ocushield and Bon Charge. While they may be more expensive, they have the research to show for the quality of their products! I like to wear my blue blockers after sunset until I go to sleep.

Manipulate your light environment.

As mentioned above, a great addition to an evening routine is viewing the sunset. After this, it is good to avoid excessive blue light or overhead lights. Both red light or candle lights are great options that are lighter on the light spectrum and somewhat mimic evening light. If you must view blue light, you can change your screen settings to emit more red or go on night time mode. Again, blue blocking glasses can also be a great investment for the evening time.

Another way to support your sleep is to make sure your room is dark and cool when you go to sleep. There are many ways to do both of these things. To keep it simple, turn electronics off, shut the door and turn the fan on. If you want to invest deeper, black out blinds and self cooling sheets are easy and affordable options.

Remember that alcohol doesn’t actually help you sleep

Many people associate a couple glasses of wine or a stiff drink with feeling sleepy. While this may be what you feel, it doesn’t necessarily support your sleep. In fact, drinking alcohol actually disrupts your sleep and wake cycles. It’s a fact that drinking alcohol can have a sedating affect in the initial stages of falling asleep, but the damage happens a few hours later. According to this study, alcohol causes fragmented and disturbed sleep in the second half of the night, when you should be in your deepest sleep state. While it’s okay to enjoy yourself time to time, avoiding nightly use of alcohol is wise for your sleep health.


While all of the things mentioned above are important, they don’t have to be complicated. Not all of us have 30 minutes in the morning, afternoon, or evening to expose our bodies to light. Some of us sleep past sunrise and work past sunset. My best advice is to keep it simple and do what works for you and your schedule. It’s extremely accessible for the average person to make a couple tweaks in their routine for circadian rhythm, it just takes a little bit of effort and consistency.

In closing, remember to have a mindset of abundance and ability. This study suggests “light at the wrong time may disrupt circadian rhythms and sleep, but in the form of light therapy, light exposure can be used as an intervention for psychiatric and other medical conditions.” What I love about this is that while the avoidance of circadian rhythm regulation can deteriorate one’s health, optimizing it can boost it. There’s no reason to feel doom and gloom over being dependent on artificial light. Making the changes needed can be free and accessible for anyone. Manipulating your light environment can quickly restore your biological clock, and being consistent with it can aid in restoring your health. Be positive and do what you can!

Much love, and see ya next blog.

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