How to Set your Circadian Rhythms with Zeitgebers (Guest Post by Michael Chapiro of Carbon Shade)

Have you ever stayed up all night? If you have, you know the terrible feeling that follows. That feeling is a reflection of the damage done to your body; insulin resistance, inflammation, and even death can occur with enough sleep deprivation. While extreme cases of insomnia are rare, many of us are guilty of chronic sleep problems. We go to bed too late, get up too early, and when we are "sleeping" the sleep is of a lesser quality due to alcohol consumption, nutritional deficiencies, and poor sleep hygiene. In this guest post by Michael Chapiro of Carbon Shade, a company that's producing a stylish blue-light blocking and sleep promoting pair of sunglasses, Michael goes over three key things you can do to start getting better sleep today. Enjoy!

Why Sleep?

Eating well is the first step to primal health, but many times we forget to take into account the interplay between the metabolism our food and the quality of our sleep. Studies show that disruptions in the circadian rhythm lead to metabolic and other health problems. Circadian disruption isn’t just about getting enough sleep, it’s about having synchronization and regulation of the entire body’s biomolecular operations.


Our circadian rhythms are like internal clocks, and the things that help "set" these clocks are called "zeitgebers". German for "time giver" or "synchronizer", the term was first coined by J├╝rgen Aschoff, one of the founders of the field of chronobiology. Aschoff proved that endogenous (internal) biological clocks exist and that these clocks are triggered by exogenous (external) cues. If you know what the zeitgebers are, and how to properly apply them, you can use this knowledge to optimize sleep through healthy and aligned circadian rhythms.

Zeitgeber #1, Food:

You’ve probably heard that eating right before bed is bad. What you might not have heard is that it's bad because calories right before bed make it difficult for your body to move into its sleep phase. In addition to when you eat, the type of food you consume during the day also matters. Diets lower in carbohydrates and higher in fat have been shown to enhance your ability to move into the sleep phase so you get to sleep earlier, regardless of when you consume your calories. Combining a low carb diet with a late night abstention from eating just be the perfect synergistic combination.

What if you like intermittent fasting and eat later in the day? Well maybe there’s a better approach that allows you to get the benefits of both fasting and healthy circadian rhythms.

Renowned polymath, Nassim Taleb, has suggest a mathematical framework for fasting regularity. Taleb suggests that our ancestors did not have regularity in fasting and neither should we—the gist of it is that one needs more variability, with fasts of increasing lengths that occur with decreasing regularity. Following this fasting protocol allows you to get more of your calories early in the day which will help entrain your circadian rhythm.

Zeitgeber #2, Temperature:

There was a recent study published that questioned how our ancestors really slept. They showed that it was most likely that people in the paleolithic era would not go to sleep immediately after the sun had set, but some hours later after the temperature had dropped. The link between sleep and the circadian rhythm is well-established. Our cozy modern homes keep us warm instead of allowing the temperature to naturally fall and this seems to be a major factor in circadian arrhythmicity.

According to Dr. Rachel Salas, MD, a neurologist at Johns Hopkins University who specializes in sleep medicine, the magic number for optimal sleep is 65 degrees. If this cites a National Sleep Foundation study that puts the magic number at 65 degrees. If this sounds too cold for you, don't worry. Dr. Salas says that anything between 65 and 69 degrees works well too. The important thing is to ensure that your bedroom is cool which helps your body natural drop in core temperature to occur. A rise in core temperature is a signal to wake up, so a hot room can send that signal prematurely, disrupting your sleep.

Zeitgeber #1, Light:

Food and temperature are great to have lined up, but the biggest part of modern society that disrupts the circadian rhythm is artificial lighting. It has been suggested that the widespread exposure to shorter wavelength light (aka blue light) through LEDs, smartphones, and laptops is having epidemic effects and could be a leading cause in obesity. It has even been directly connected to an increased cancer risk.

Blue light is the type of light found in natural sunlight, so another problem is that we don't get outside enough during the day to get blue light exposure when we need it. Essentially we have a two-fold light problem. Too much blue light at night, and not enough blue light during the day.

The solution for the first part of the problem, too much blue light at night, could be handled Paleo-style, you could move into a cave, but if you don’t want to miss out on the perks of modernity, you could wear special glasses (like Carbon Shades) that block the harmful blue light while still allowing you to use your devices. You could also install programs like f.lux onto your computer or put low blue light lightbulbs into light fixtures that you turn on at night. Basically it's like a night light for adults that helps you go to sleep!

The solution for the second part of the problem, too little blue light during the day, is simple. Get outside! Going for a walk during the middle of the day, opening up windows to let natural light into your house, or, if all else fails, purchasing a "sun lamp" that has a high output of blue light can help entrain your proper daytime rhythm.


For optimal sleep, consume a low-carbohydrate diet, avoid eating at night, sleep in a cool room (between 65-69 degrees), and ensure that you get blue light during the day and that you avoid blue light at night.

Doing these things will "set" your circadian rhythms for optimal health, longevity, performance, and appearance. Plus you'll feel great too, so there's no reason not to get your zeitgebers in order!

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About Unknown

Tony is the host of the Paleo Magazine Radio podcast, author of "Paleo Grilling: A Modern Caveman's Guide to Cooking with Fire", and Cofounder of Powerful PT, an innovative information resource for Fitness Professionals. He has appeared on numerous local and national television and radio broadcasts and regularly hosts healthy cooking workshops and informational lectures. He is also a full-time Personal Trainer and Wellness Consultant who lives in Jacksonville Florida with his wife Jamie.
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