L is for Light

What is there about the sunrise which draws us from slumber? Why does the television wake you up…even when all that is on is ant races? What are you seeing you do not realize you are seeing? Light. Blue light to be completely specific. But this is no sale notification. It is a direct line to your biological clock.

We all learned in biology about the rods and cones in our eyeballs which make us see light and color, respectively. What we did not learn about was the other kind of receptors in our eyes which do not send information to our visual cortex through the optic nerve. Instead, these light receptors are connected to the hypothalamus in the center of the brain which houses our biological clocks.

Life Clock

Not to be confused with the biological fertility clock which counts years, your biological life clock keeps time in days. The life clock tells you when it is time to get up, when to go to sleep, when to eat and so on. It measures time based on light.

No pills. Go outside. Eat healthful foods.

Different frequencies of light trigger different responses for your clock. Why? Light regulates different chemicals in your body. The most studied chemicals are Vitamin D and serotonin.

Vitamin D helps your body to absorb calcium from food you eat and milk you drink to make bones and teeth. The most natural way to get Vitamin D is to be exposed to direct sunlight. Your body will make it naturally.

Serotonin is a brain chemical which induces sleep. Your body makes its own sleep aid everyday. So, why are you still awake?


Light suppresses the body’s production of serotonin.  In the same way light makes the body produce Vitamin D, it keeps the body from producing enough serotonin to induce sleep. This is why you will hear adults tell you they cannot possibly take a nap during the day or sleep past mid morning.

When the sun creeps through the window and pierces your eyelids (you can see through them), the light tells your brain to stop soaking in the serotonin, which has put your biological clock to sleep for the night. As the serotonin level drops, you wake up.

The human eye can detect a spectrum of light between 400 and 700 nano meters (billionths of meters). 400 nm is violet light, and 700 nm is the longest frequency of red light we can see. Blue light is 475 nm.

On sunny days, the blue light is scattered through the atmosphere (making the sky appear to be blue). You feel more energized because that sleepy serotonin production is down. On overcast days, the blue light is more scarce, and your serotonin level creeps up, making you want to snuggle into bed for a nap.


Your life clock gets confused when you infuse it with light at times it is not expecting. You are parading optical illusions in front of it. Blue light, like the sunshine which gets you up in the morning, is emanating from your television and computer screens. (Waits patiently for epiphany.)

Like turning on a Q-beam.

So, if you are trying to relax or unwind in front of a screen between 2.5 and 60 inches, your entertainment is keeping you awake and making it nearly impossible for your body to put your brain to sleep. Sleep studies prove being exposed to blue light, even while you are sleeping, causes the serotonin level to drop and disrupt sleep.

What color is your night light? That cool blue is not what is going to make it easy to go back to sleep after traipsing down the hall. It may have saved your toe from finding the door jamb, but it is not going to help you find any ZZZ. Try a warm yellow one instead.


Lots of research into light therapy proves light helps lift sagging moods for those who live near the poles (six months of darkness), depression sufferers and those with bipolar disorder. New light boxes, which are used in the morning to decrease serotonin, are available in blue light, with only one warning. Macular degeneration is a risk of serial exposure to blue light if you already have risk factors for the retinal dysfunction. The jury is still out on how much, how often and for how long.

Windows XP logo

How many blue logos do you know?

Blue light is pleasing for quite a few reasons. It is no wonder it is the most chosen background color for your standard computer programs, television programs, paint and more. Cheer and energize yourself. Let the blue light shine.


Do you use cool blue or warm yellow light in your home? Have you worked in a place with blue light (titanium, mercury or fluorescent)? What is your favorite color of light? What other blue light logos do you know?

(c) Ann Marie Dwyer 2012
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