Circadian Rhythm Metabolism

What is Circadian Rhythm?

What is Circadian Rhythm?

Do you struggle with

  • Falling or staying asleep?
  • Afternoon fatigue?
  • Stubborn weight loss?
  • High blood sugar?

You may be experiencing disrupted Circadian Rhythms and some simple changes to lifestyle patterns could be part of the solution.

Circadian rhythm is the physical, mental, and behavioral patterns of all animals, plants, and microbes in a near 24-hour rhythm.  Sunlight heavily influences circadian rhythm through light-sensing proteins called melanopsin. Humans have been in harmony with the sun for so long that the circadian rhythm of the sun is encoded in our DNA.

Your body uses circadian rhythms to sleep, wake up, and make energy so you can move, digest, and think.  Each organ has its own time to work, and its own time to rest and repair.  For example, your digestive tract works when you eat and rests when you fast, like when you’re sleeping.  Knowing that circadian rhythm plays such a critical role in your body’s metabolism, researchers are making links between disruption of circadian rhythm and Metabolic Syndrome.  Metabolic Syndrome is a condition characterized by elevated cholesterol, blood sugar and body weight.

Our modern life encourages us to eat, sleep, exercise and socialize around the clock. Thanks to electricity, refrigerators, and late-night Door Dash, we can get all these things pretty much any time we want.  But these activities throw our bodies out of balance with the timing of our circadian patterns and thereby out of balance metabolically.

Researchers studying Circadian Rhythms have identified signals, called Zeitgebers (a German word for “time givers”), that help keep our clock in sync. The most significant of these being light.

Rhythm & Light Exposure

Exposure to light activates the hypothalamus part of our brains.  There are 20,000 neurons queued to receive light signals in your retina and are collectively called the “Suprachiasmatic Nucleus”, or SCN.  The SCN functions as the master regulator of sleep, feeding, glucose metabolism and even learning and memory.  It also communicates with the pineal gland of the brain to regulate the rhythmic secretion of melatonin, the hormone that helps you fall asleep and the autonomic nervous system to release cortisol to help wake you up.

Not all colors of light have the same effect on circadian rhythms.  Blue wavelengths tend to be the most disruptive and can significantly suppress your body’s production of melatonin.  Sunlight has the most blue light, but when the sun goes down we get blue light exposure from fluorescent light, LEDs, televisions, computer monitors, tablets and smart screens.

Rhythm & Eating

Another important Zietgeber that is becoming increasingly linked to Circadian Rhythm is eating.  While light tends to influence the SCN in the brain, food seems to have a greater effect on other tissues, especially the liver. The liver helps to relay hormone messengers that link the SCN in a feedback loop while also helping to regulate blood sugar.  (Yes, your liver does much more than just detox!)

Your body is adapted to eating during the day and so naturally your metabolism, or energy use, slows down at night. Eating when metabolism is slow, causes more energy storage in adipose  (fat cells).  Consider this statement by circadian researcher, Satchin Panda, in his book The Circadian Code, “It is hard enough for the body to monitor hormones, genes, and clocks for someone with a strict eating routine. But when eating occurs at random times throughout the day and night, the fat-making process stays on all the time.”

Rhythm & Energy Expenditure

Exercise is usually what comes to mind when you think of using energy, but your body is using energy right now to keep your heart beating, blood flowing and body temperature in range.  If you’ve recently eaten, your body is also using energy to digest food.  It should be no surprise by now that heart rate and body temperature are also part of your circadian rhythms.  Exercise late at night is not a good idea for sleep, while exercise in the morning can help synchronize the circadian rhythm and improve alertness.

Synchronize with Entrainment

Synchronizing the circadian rhythm is called “entrainment”.  If you’ve ever tried to simultaneously pat your head and rub your stomach you know that it takes concentration.  If you don’t concentrate, you can easily fall into patting both your head and stomach.  The body really does want to be in sync.

Here are some tips to putting your lifestyle back into sync with your circadian rhythm:

  1. Go outside as soon as you can after waking. This will help your body set the “wake” switch. This a great time for a short walk or sit outside with your coffee or tea.
  2. Spend time outside in the sunlight without sunglasses for as long as possible every day.
  3. Check your Vitamin D levels and supplement if your level is below 35. (Vitamin D is important to the production of melatonin.)
  4. Schedule your exercise during daylight hours.
  5. Try to eat all your food within 8-10 hours of the day, for example 8:00am – 6:00pm.
  6. Stop eating 2-3 hours before bed.
  7. Avoid napping.
  8. Turn down lights in the evening when the sun goes down and avoid brightly lit places at night, such as the grocery store.
  9. Shut off screens or block blue light in the evening using f.lux, your device’s night mode, or blue light-blocking glasses.
  10. Try to keep a consistent sleep and wake time, even on weekends.

Aligning Your Own Circadian Rhythm

Arguably, not everyone’s lifestyle can support circadian rhythm 100% of the time.  If you’re a shift worker, college student or just love late-night movies, doing your best to fit your lifestyle into your body’s circadian rhythms can be a challenge.  Select the tips above that you can make work for you and notice how your body responds.  If you have trouble sleeping, fatigue, stubborn weight loss or have been diagnosed with Metabolic Syndrome and want additional support, schedule an appointment with me, Stacy St Germain, and I can help you create your own action plan to circadian entrainment.

“When the rhythms of our body-mind are in synch with nature’s rhythms, when we are living in harmony with life, we are living in the state of grace. To live in grace is to experience that state of consciousness where things flow effortlessly and our desires are easily fulfilled.”
~Deepak Chopra


Metabolism & the Circadian Clock Converge

How to Fix a Broken Clock

Health Lies in Healthy Circadian Habits


Disclaimer: Nutrition therapy is not intended as a diagnosis, treatment, prescription, or cure for any disease, or as a substitute for medical care. Jen Marshall and Stacy St Germain are not licensed medical providers. Nutrition plans are not intended as a substitution for traditional medical care, nor should be interpreted as medical advice, but instead is an adjunctive and supportive therapy.