Light and the Saber Tooth Tiger

Lately, I have spent time considering how light impacts our circadian rhythm and the production of melatonin.  Melatonin is produced by various tissues in the body, although the major source is the pineal gland in the brain activated by darkness.  Why is this so sensitive to light?  How is it that even a small amount of blue light can disrupt this?

 I am brought to the awareness that each of us on this planet had ancestors who were able to survive famines, disease and predators, if they had not we would not be here.  In order to survive our ancestors had amazing genetic qualities to survive all that they faced and these they passed down to us in our genetic code.  

So, what does this have to do with light and the saber tooth?  When our ancestors experienced light it meant that the saber tooth or other predators also had light and for survival they had to be alert and awake.  The production of melatonin and the drowsiness it brings could have meant their doom.  Today, our pineal gland is not able to differentiate between the electric 24 hours a day of light we are able to surround ourselves with and the light that meant it is time to be awake and alert.  

We need to figure out how to work with our light sources to support our biological needs and responses to light, as they won't be changing any time soon, so for our health and survival we must understand this and work to support our natural systems.