It’s thought that the first cells on Earth were damaged by UV light from the Sun and adapted by repairing themselves at night.

It’s also thought that any life form that derives energy from the sunlight has some kind of circadian rhythm, to make the most of light and darkness.

Circadian rhythms allow organisms to anticipate events such as night and day, winter and summer and so prepare themselves for those events.

Animals and other wildlife know when to mate and hibernate.

1. You have a Master Clock

It sits in the hypothalamus deep in your brain and, like an orchestral conductor, sends regulating signals throughout your body at different times of the day.

2. You have Peripheral Clocks too

These are found in all your organs and body tissues and are synchronised by the Master Clock, the hypothalamus in your brain. Traditional Chinese Medicine divides the 24 hour clock cycle into body organs and functions, each having a 2 hour period of maximum function. I’ll write about this in more detail further on.

3.You have Clocks in every Cell too

Every cell in your body has the capacity to generate a 24-oscillation.

4. Circannual Rhythms

As nights grow longer and sleep lengthens, our brains release more melatonin, causing us to feel drowsy, the precursor to sleep. It’s thought humans produce more antibodies to fight off winter illness.

5.Daylight keeps your Clock regular

From the moment you wake up in the morning, the eye sensors detect light and sends signals to the part of the brain that keeps your body clock in sync. Sleep pressure builds up during the day. However, you do not usually fall asleep until your biological clock tells you it is the right time to drop off, this being triggered by reduced light levels. If you were left in the dark your body clock would become out of step with the 24 hour master clock.

6. Sunlight & Serotonin

The light induced effects of serotonin are triggered by sunlight that goes through the eye. Sunlight cues special areas in the retina, which triggers the release of serotonin by the brain. Serotonin is associated with boosting mood and helping us feel calm and focused. Serotonin is the precursor to melatonin and is a powerful transmitter in the central nervous system acting on the digestive tract and regulates physiological mechanisms such as body temperature, motor control and as described, the circadian rhythm. Serotonin regulates our sleep-wake cycles. When we associate our optimum sleep cycle with the times our body is regulating organs from a TCM perspective, we can understand the importance of ‘Getting a good night’s sleep.’ Serotonin is an important neurotransmitter in the descending analgesic pathway from the brain stem to the dorsal horn of the spinal cord, which is important in pain relief. Studies have shown that low levels of serotonin and serotonin receptors with depression and related conditions. Serotonin has also been shown to have a positive effect on stress-prevention and aging.

7. Jet Lag & Social Jet Lag

You feel jet lagged when your body’s master clock is one time and other parts of the body such as your liver, gut, brains and muscles are at slightly different times. It takes about one day for every time zone crossed for them to synchronise again. Shift workers and others who have a mismatch between their biological time and social time can experience a ‘social jet lag’. The difference between the time their body wants to wake up and the time the alarm goes off. Sleeping in and staying up late play havoc with healthy sleep patterns and can lead to reduced energy, low mood, poor digestive function, and more. Studies suggest a correlation between this and the increased risk of depression, obesity, heart disease, diabetes and cancer.

8. Understanding and Aligning with our Circadian Rhythms

Circadian Rhythms, their role of how our systems are regulated with light through the visual and circadian light perception, with their diverse affects across our molecular, cellular, anatomical and behavioural aspects have direct implications for human performance, productivity and health. Alongside, diet, exercise and water etc, we would be well advised to include daylight with its role and our Master Clock.