Everything you need to know about circadian rhythms
With over 500 resources and 1000 references, circadian is the ultimate guide for learning about the most important aspect of your health.
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All the leading-edge science about circadian rhythms all easily accessible in one place
Circadian Rhythms: an introduction
Life has evolved around the natural light-and-dark cycles. Plants and animals have developed internal biological clocks to stay in sync with these cycles.1 These clocks allow organisms to anticipate and prepare for regular environmental changes as well as regulate and coordinate internal metabolic processes.2
Your body’s circadian rhythms are 24-hour cycles of biological, hormonal, and behavioural patterns.3 These rhythms modulate a wide array of physiological processes, including the body’s production of hormones that regulate sleep, hunger, and metabolism. Ultimately, these rhythms regulate your body weight, performance, mood, and susceptibility to disease.4 At least 50% of human gene expression is under circadian control.5 As such, circadian rhythmicity has profound implications for human wellbeing and longevity.
The master conductor of your circadian rhythm is a small bundle of nerves in the

The master conductor of your circadian rhythm is a small bundle of nerves in the hypothalamus region of the brain called the suprachiasmatic nucleus (SCN).6 The SCN is directly linked to your eye. Your organs, tissues, and cells have clock genes that regulate and coordinate their biochemical processes. These peripheral clocks need to be synchronised with your master clock in the SCN to do their job well. You might be surprised to find out that almost every cell in your body has a clock that is programmed to turn on and off thousands of genes at different times of the day and night.5,7
we can now say, emphatically, that the function of our entire metabolism is dependent on light
-Prof Dr Fritz-Albert Popp
Although circadian rhythms are internal, they are entrained to your local environment by external cues such as light and temperature.8 Peripheral clocks in your gut and liver, for example, are entrained by when you eat,9 whereas clocks in your muscles are entrained by when you move.10
If the trillions of clocks in your cells are playing in tune and follow their conductor (SCN), you have a wonderfully harmonious, intricate, and resonant concert. Provided your SCN is aligned with the natural light-and-dark cycles. If a bunch of clocks are playing to their own tune, dissonance and chaos are the result. This is equivalent to inflammation and eventually leads to disease.
Your daily activities and environment are either supporting internal harmony or internal chaos. Getting the right circadian cues (light/darkness, food, exercise, temperature) at the right time is non-negotiable for a healthy body, mind, and heart.11 Setting a daily schedule that reinforces your body’s natural rhythm is the most potent health habit you can adopt. Ideally, you are nourishing, moving, and resting your body in sync with nature. Are you ready to make some changes?
Circadian can help you create a life that is aligned and in tune with the natural cycles.12 Your lifestyle and your schedule can become the source of your vitality and longevity.13 It is a matter of putting your biological schedule first.