Circadian Rhythm: Your Body’s Master Clock (Part 2)
In Part One, we discussed why circadian rhythm is such a foundational piece of health and how your body uses environmental signals to coordinate energy, hormones, metabolism, digestion, immune function, and sleep.
Now the question becomes:
How do we actually improve it?
The answer is surprisingly simple.
Your body needs strong, consistent signals that tell it when to be awake, active, and alert, and when to slow down, repair, and recover.
The two most powerful signals are:
Bright light during the day, especially morning sunlight.
Darkness at night, especially reducing blue light exposure in the evening.
These are where many of the biggest disruptions occur in modern life.
The exciting part is that improving your circadian rhythm is one of the most powerful health interventions you can do, and it is completely free. It does not require expensive supplements, specialized testing, or complicated routines to begin making progress. It starts with small changes to the signals you give your body every day.
Think of your circadian rhythm like a single daily heartbeat . You only get one major circadian signal every 24 hours (one heartbeat). The goal is to make that signal strong, consistent, and happen at the right time.
Your daily inputs help set that rhythm.
The goal is not perfection. The goal is to give your body clearer, more consistent information.
When the inputs improve, the systems they influence can become better regulated.
The Simple Daily Circadian Rhythm Practice
If you only focus on a few things, start here:
Get outside for 5–20 minutes at sunrise (ideal) or as close to waking as possible. Even 1 minute is better than none.
Eat a protein-rich breakfast within an hour of morning light exposure.
Get natural sunlight throughout the day, especially midday.
After sunset, turn off overhead lights, switch to low warm lighting, and wear red-tinted blue light blocking glasses to minimize blue light exposure.
Sleep in total darkness using blackout shades or a sleep mask.
These five habits create the foundation for a stronger circadian rhythm.
1. Get Morning Sunlight to Set Your Internal Clock
Morning sunlight is one of the strongest circadian signals available.
When light enters your eyes in the morning, specialized cells in your retina communicate with your brain’s master clock. This tells your body that a new day has started and begins coordinating the rhythms that influence energy, hormones, metabolism, and sleep later that night.
Ideally, get outside within 30 minutes of waking.
Aim for:
5–20 minutes of natural sunlight exposure
Earlier is better
Sunrise is ideal
Even one minute is better than none
Whenever possible, get this light exposure without glasses, contacts, or sunglasses. “Naked eyes” allow for the light signal to hit the eye unchanged, giving the brain the most consistent information.
You do not need to stare directly at the sun. Simply being outside and allowing natural light to reach your eyes is enough.
Facing east toward the rising sun can provide a stronger signal, but the most important thing is simply getting outside.
Morning sunlight helps:
Improve daytime alertness
Support a healthy cortisol rhythm
Improve mood
Prepare your body for better sleep later that evening
If possible, combine sunlight with movement. A morning walk or stretching routine is one of the simplest ways to reinforce the signal that daytime has arrived.
2. Make Your Days Bright
Your body needs a strong contrast between daytime and nighttime.
Bright days create a stronger biological signal for dark nights.
Indoor lighting, even in a well-lit building, is much weaker than natural sunlight outdoors.
Throughout the day, try to:
Spend time outside
Take outdoor walking breaks
Exercise outside when possible
Get midday sunlight exposure
Your body uses these environmental cues to understand when it should be active, alert, and productive.
3. Eat With Your Circadian Rhythm
Food is another important biological signal.
Your digestive system, liver, pancreas, and metabolism all follow daily rhythms. When and how often you eat can influence these systems.
Helpful strategies:
Eat meals around consistent times
Prioritize protein earlier in the day
Eat most of your calories during daylight hours when possible
Avoid large meals right before bed
Give your digestive system time to rest overnight
A protein-rich breakfast after morning light exposure is a simple way to reinforce the daytime signal.
Your body is designed for nourishment and activity during the day and repair at night.
4. Dim Your Environment After Sunset
As the sun goes down, your body expects a transition into nighttime.
For thousands of years, sunset naturally signaled the beginning of the recovery phase of the day. Light levels decreased, the environment became darker, and the body began preparing for rest.
Modern life often creates the opposite environment.
Many people spend their evenings surrounded by bright overhead lights, white LED bulbs, and brightly lit rooms. These signals tell your brain that it is still daytime and can interfere with your natural nighttime rhythm.
Light is one of the strongest regulators of your circadian clock.
Simple changes can make a big difference:
Turn off overhead lights after sunset
Use lamps instead of ceiling lights
Choose warm or amber-colored bulbs
Keep lighting low and indirect in the evening
Think about creating a sunset inside your home.
Your environment should gradually become darker as the day ends, helping your body recognize that nighttime has arrived.
5. Limit Screen Time Before Bed and Block Blue Light After Sunset
This is one of the most important areas where circadian rhythm and sleep overlap.
For many people, the biggest circadian disruptions come from poor morning light exposure and excessive artificial light exposure at night.
These two signals have the greatest ability to shift your internal clock in the wrong direction.
I covered sleep more extensively in my previous blogs, “Sleep as THE Foundation of Health,” including sleep timing, caffeine, exercise, bedroom environment, and troubleshooting common sleep issues. Many of the strategies overlap because both topics come back to the same foundation:
Giving your body the right signals at the right time.
Ideally, screens are avoided for at least an hour before bed.
However, real life does not always allow for that.
If you are going to use screens at night, blue light blocking becomes an important tool.
Screens emit a high concentration of blue light, which can suppress melatonin production and signal to your brain that it is still daytime.
Melatonin is one of the key hormones involved in sleep initiation. The more melatonin you produce through the evening and into the night, the sleepier you become.
Exposure to blue light at night can delay this process by telling your brain that daytime conditions are still present, therefore decreasing melatonin production.
This can make it harder to fall asleep, delay your natural sleep timing, and reduce the quality of your sleep.
The most important wavelengths to block are 400–530 nanometers, which are the wavelengths most involved in disrupting melatonin production. These fall within the blue and green spectrum.
Red-tinted blue light blocking glasses are drastically better at blocking these specific wavelengths compared to typical daytime blue light glasses.
They do not make screens harmless, but they significantly reduce the biological signal that keeps your brain alert when you should be transitioning toward sleep.
Inexpensive, no-frills, highly effective options (what I personally use):
Spectra479 Nighttime Glasses:
https://spectra479.com/products/night-shades-blue-blocking-nighttime-eye-wear
Clip on over prescription glasses:
https://spectra479.com/pages/blue-blocking-prescription-glasses
Higher-end option
Swanwick Sleep Night Glasses:
https://www.swanwicksleep.com/products/classic-night-swannies
The most important thing is not the brand. It is that the lenses actually block the wavelengths that interfere with melatonin production. Both of the above products meet this requirement.
Additional strategies:
Lower screen brightness
Use night mode settings
Avoid stimulating content before bed
Reduce unnecessary screen time late at night
6. Sleep in Complete Darkness
Your body expects nighttime to be dark.
Even small amounts of light exposure during sleep can send signals to your brain that the environment is not completely dark.
Helpful strategies:
Use blackout curtains
Use a sleep mask
Cover small LED lights
Keep electronics away from the bed
A cool, dark bedroom helps create the ideal environment for deep, restorative sleep.
7. Keep a Consistent Sleep and Wake Schedule
Your body loves consistency.
Going to bed and waking up at similar times each day helps strengthen your internal clock.
This applies to weekends too.
Large changes in your schedule can create a “social jet lag” effect, making it harder to feel energized and alert.
You do not need a perfect schedule. You need a predictable one. Aim to go to sleep and wake up within the same one-hour window each day.
For more information on sleep timing, improving sleep quality, and troubleshooting common sleep problems, refer back to my sleep blog series.
8. Move Your Body During the Day
Movement is another important signal that reinforces daytime.
Exercise supports:
Energy production
Metabolism
Blood sugar regulation
Sleep quality
Whenever possible, get movement and exercise during daylight hours.
The Takeaway
Circadian rhythm is one of the most overlooked foundations of health.
The solution doesn’t have to be complicated:
Give your body strong signals during the day.
Give your body darkness and recovery at night.
The goal is not perfection. The goal is consistency.
Your body is constantly listening to the information you provide.
When those signals become clearer, your body can better regulate the systems that influence your health.
Bright days. Dark nights. Consistent rhythms.
Work with your biology instead of against it.
In health,
Dr. Ryan Gengler, DC
