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.

Lighting Safety Consideration


Most people don’t give a lot of thought to their lighting until you flip a switch and the light doesn’t go on.  For many of us this is a nuisance although one that can be fixed with relative ease.

 Now consider you are older, live independently, or have some mobility concerns and your hallway light doesn’t come on when you flip the switch.  It is evening time and to be able to see to get to your bathroom and bedroom you need that light, which is burned out.  The steps to change the light include, getting the step stool, having a replacement bulb on hand, climbing the step stool, being able to unscrew the burned out bulb, install the new one, climb back down the step stool and return it to the closet or garage.  There are many points in this process that could be dangerous and be the cause of an injury.

If this bulb is a regular incandescent this is a process that will be repeated with frequency as this hallway light is used.  What are the choices to limit the need for this change out?  CFL’s – the curly q lights do have a longer life, although it is shortened with frequent on and offs, it does have a warm up time to reach its full light output, it also contains mercury so if it is broken in this process is a hazard requiring special clean up and disposal.  The most important consideration for me when using a CFL is if this is a transition placement where I will want full light when I turn on this light- a hallway, stairway, bathroom, garage, front door are all places where I will want light immediately so not where I would use a CFL.  LED’s are now becoming more economical to purchase, they are a major energy saver when compared to the incandescent and they have a life of 10-20 years.  This is a choice that most likely will eliminate the need for a change of this light for as long you are living in this home. 

If you have an older loved one or someone with mobility concerns who is living in their own home a switch in the lights that are essential for their safety to LED’s would be a very good investment in their safety and security.