Our brain has a pea-sized part called the hypothalamus, which is responsible for basic functions such as hunger & thirst management, body temperature regulation, etc.
There is an even smaller part (half the size of a choco-chip) in the hypothalamus, called SupraChiasmatic Nucleus (SCN), which is called the time-keeper of the body.
The main function of SCN is to monitor the light that enters our bodies through our eyes and inform the hypothalamus so that the hypothalmus could influence the release of hormones to get things done.
Now, visible light enters our eyes in some sort of coloured packets – Violet, Indigo, Blue, Green, Yellow, Orange, Red.
And while all lights have some role to play and they enter simultaneously, it is the blue light that is responsible for getting SCN into action.
As soon as it senses the blue-light, SCN informs the hypothalamus, which sends hormones and signals to various organs to perform certain tasks.
One of the things that the hypothalamus does, upon receiving the information about blue-light, is that it activates peristalsis.
Peristalsis means tightening and relaxation of the muscles of the intestine, creating wave-like movements that push the contents through the digestive tract.
Historically, the blue light came only from the sun and so, over the centuries, the sun has come to regulate our natural sleep and wake cycles.
When we are asleep, the intestine works to process all the food leftover from the previous day.
But in the first hour of our exposure to blue light each morning, peristalsis is three times stronger as compared to when we are sleeping (since it is about muscles, some tightening and relaxation happens all the time).
For some people, blue light just warms up the system and they need a cup of tea, coffee, or a glass of water to get the peristalsis fully activated.
Today, there are many sources of blue light (TV, mobile, LED lights etc.), which replicate what the sunlight did for our ancestors but, at the same time, untimely or over exposure to blue light from these sources can disrupt our sleep-wake cycles and the digestive systems, therefore.
