But there is a master clock, a conductor as such, the suprachiasmatic nucleus (SCN). It’s located in the hypothalamus in the brain, and controls all these clocks, keeping them synchronized. Like so many of our bodily processes its complicated but let’s break it down as best we can.
Light is one of the main factors that drives its daily operation so let’s start with the morning light.
As we all experience daily (unless its winter in the far far north….), the sun rises and lights up the environment. This light enters the retina in your eye, and travels to the SCN which in turn triggers a response in the pineal gland, also in the brain. The pineal gland is responsible for the secretion of melatonin, a magical hormone which optimizes everything in our body, but mostly famous as the sleep hormone.
Now back to light…
Exposure to light suppresses the secretion of melatonin, and in turn, switches on another hormone process, the release of cortisol, our alert hormone. These hormones are in opposite relationship; when melatonin is high, cortisol should be low, and vice versa. It’s this intricate daily dance we go through keeping us alert during the day and asleep at night, if everything is going according to plan…
But our modern lifestyle changes things…
Our eyes are bombarded with light at night, which confuses our brain, sending all kinds of wrong signals and disrupting these hormones. One of the most damaging affects of night at light is our pineal gland not producing and secreting melatonin when its needed to make us sleepy. How can it when light from our screens and modern lightbulbs is still reaching it. No wonder we don’t feel sleepy after hours of light exposure when it’s dark. We don’t have enough melatonin in our bloodstream.
