Just like digestion, sleep and wake cycles are generally overlooked as a cause of ill-health. Strange that, especially when you consider the processes your body undergoes when you are asleep and how important those processes are in terms of allowing your body to fix and repair any damage caused by the stressful lifestyles we all lead in the modern era.


Compared to the time before light bulbs were invented and commonplace in every household (about 80 years ago), nowadays we all stay up too long watching late night telly with bright lights at the touch of a switch. It's all too easy now to forget that for thousands of years we lived in sync with the light and dark cycles of day and night. These cycles have become hard-wired into our systems. Our hormones in particular are closely synched with them. Our physiology is still near enough the same as our sun-driven ancestors and our bodies remain tuned to the natural rhythm of daily sunrises and sunsets.

Circadian Rhythm

These natural 24 hour cycles are known as circadian rhythm and as I mentioned they dictate when our bodies release certain 'get up and go' hormones and specific 'recover and re-generate' hormones. The circadian rhythm cycles between light (Yang) and dark (Yin), which is a direct result of the rotation of our planet and the movement around the sun. Its pretty cool to think that our own hormonal systems reflect the movements of the planets and that our sleep patterns and therefore our health is hard-wired into the universe ! Whenever light shines on your skin or in your eyes, your body is stimulated into action and your brain and your hormonal system thinks its time to get up and do stuff. In response to any form of light (natural or artificial) your hormonal system responds by releasing cortisol, the stress hormone. Remember light is essentially a form of electromagnetic stress that in excessive amounts can lead to increases in physiological load. Cortisols primary purpose is to activate the body in preparation for movement, work, combat or any activity necessary for survival.

Light = Cortisol = Daytime Activity

In the morning, as the sun rises, our cortisol levels rise and our Sympathetic Nervous System is most active but by the late afternoon cortisol levels have dropped again and the Parasympathetic Nervous System becomes more active, especially as the sun goes down. It's in the evening that our bodies increase the release of melatonin and other growth and repair hormones in an attempt to fix any damage caused by the days activities. Research shows that by 10pm we should be asleep, allowing the body to properly repair and regenerate the physical body up until 2am. From 2am the immune system goes about repairing the mental aspects of the brain and the body which lasts until we awaken.

Dark = Repair Hormones = Night Time

So if you go to bed regularly at midnight, you've already missed 2 hours of physical repair - Not good if you're trying to recover from a hard workout, trying to build muscle or repair your body after a stressful day !

Disrupted Sleep/Wake Cycles

If stress levels throughout the day are high then the levels of cortisol become elevated above the norm. A continual release of the stress hormone would be helpful for a hunter or anyone in a survival situation but this should not be a daily occurence. If cortisol is too high the ability of the body to repair and regenerate becomes suppressed and eventually this leads to a breakdown of tissue and the onset of ill-health. So working on your laptop, late into the evening in a brightly lit room, or watching late night TV or in fact any cause of excessive stress can lead to a disrupted sleep/wake cycle and excessive cortisol, throwing the hormonal system out of balance and thus preventing the body from releasing hormones like Growth Hormone, Melatonin and even Testosterone. Its these repair hormones that help the body to fix itself during the night. A disrupted sleep/wake cycle can result in adrenal fatigue due to the overproduction of cortisol. When the adrenals become exhausted the body becomes exposed to infection and you can expect to experience symptoms such as headaches, neck pain, anxiety, forgetfulness and it even effects your ability to digest food, build muscle, increase metabolism and burn fat !

We all need to respect our natural circadian rhythms :

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