(hla) DID you know that the Circadian Rhythm is a crucial aspect of our physiological processes that can affect your health?  The Circadian Rhythm is the physical, mental and behavioural changes that follow the 24 hours cycle and is found in most living things including animals, plants, and many tiny microbes .It responds to light and darkness in the environment around an organism.

The time we sleep and wake up is determined by the circadian rhythm. In fact, our entire life schedule revolves around it. In humans, the circadian rhythm is located in the Suprachiasmatic Nucleus (SCN), which is a pair of distinct group of cells located in the hypothalamus. It begins from a group of cells in the retina of the eyes called the photosensitive retinal ganglion cell that detects the brightness, and then sends signal to the Suprachiasmatic Nucleus (also known as the Master Clock).

There are several ways in which we can best utilise the Circadian Rhythm to our benefit. Familiarising ourselves with the Circadian Rhythm enables us in knowing the best time to carry out certain activities.


1.  Exposure to Light
We need sunlight. While most people shun themselves away from the sun with the notion that it may make them vulnerable to skin cancer, research has shown that a sensible amount of sun actually reduces several cancers and other serious health conditions. The Journal of National Cancer Institute reported that patients who have "had a history of sun workshopping" are more likely to survive the early stages of melanoma, the deadliest form of skin cancer. Nonetheless, the exposure to sun should be reasonable and precautions of overexposure should always be taken. For those who want to be safe from harmful UV rays, it will be interesting to take note that the first half an hour after sunrise and last half an hour before sunset is when the UV rays are "zero".

Exercise such as brisk walking or jogging for at least 20 minutes without sunglasses can help strengthen the body clock. According to the Journal of Physiology published on the US National Library of Medicine (Exercise strengthens Circadian Clocks by Mary E Harrington), studies actually suggested that exercise can alter "fundamental properties of circadian system components".

Night is when we need to avoid exposure to bright light, including the blue and white light spectrum. The secretion of melatonin at night helps us sleep. Melatonin is a powerful hormone that helps us boost our immune system to fight diseases and prevents cancer. High melatonin levels improve diabetes, glaucoma, hypertension, irregular bowel syndrome etc.

Melatonin secretion start at 9 p.m., Knowing this, we should already prepare for bedtime by avoiding stimulating activities such as watching television, browsing the internet during bedtime and ensure that the bedroom has dim lighting because even a small amount of light may disrupt the secretion of melatonin, which in turn disrupts the entire circadian rhythm and affects the restoration of health. Meditation before bedtime is a wonderful practice that can help the mind and body rest to prepare for a good night's sleep.



2.  Food consumption.
The Circadian Rhythm also affects the digestive system. The best time to consume food is during daylight hours as it equips us with the energy to carry out our activities. A good breakfast is a good start of the day, followed by a good lunch for us to carry out exercise in the evening around 5 p.m. (as this is the time when cardiovascular efficiency and muscle strength is at its best). Following the rhythm of the body, dinner is actually unnecessary as the body is supposed to prepare to rest and sleep. Consuming food at night will prevent the body from resting as the digestive organs continue to work throughout the night.


3.  Schedule your daily activities effectively
Knowing the Circadian Rhythm helps us schedule our daily activities in an effective manner to achieve optimal health. The diagram below shows how our body works according to the different times of the day:




Circadian rhythms are adapted to optimise the daily rhythm in all living beings. When we engage in activities at the times when the biological circadian processes are conducive to the specific activity, we can then obtain optimal efficiency. Take a look at how our body reacts according to the different times of day:


Morning (6 a.m. to 10 a.m.)
The sun rise signals us to wake up. Sensory recovery gradually happens and we will wake up and become more alert as the time passes. The body temperature rises progressively upon waking and plays a major role in alertness and function. Blood levels of the cortisol hormones begin to increase and melatonin hormones start dropping.

About two or three hours after waking up, the body temperature and cortisol create an optimum environment for cognitive-based activities. Examples of cognitive-based activities include recognising knowledge/facts, problem-solving, making evaluation and judgement, giving ideas etc.


Afternoon (12 p.m. to 3 p.m.)
Cortisol hormones drop sharply, causing a dip in performance during afternoon hours. A short afternoon nap and exercise may help improve mental health.


Late afternoon (3 p.m. to 6 p.m.)
Body temperature will reach its peak and the greatest cardiovascular efficiency and muscle strength is during this time. This is the greatest time for physical activities. However, if the physical activities are done too late in the evening, this can delay the secretion of melatonin and therefore delay our sleep schedule, disrupting our sleep pattern.


Evening (6 p.m. to 10 p.m.)
The melatonin level begins to rise and cortisol level starts to drop. This is the time for us to relax and prepare for sleep.


Sleep (10 p.m. to 6 a.m.)
Sleep begins at 10 p.m. and the deepest sleep that we will experience is at around 2 a.m.


Getting acquainted with how the circadian rhythm plays a role in maintaining and restoring physiological functions enable us to schedule our lifestyle efficiently so that we may optimise processes to achieve optimal health.