Light effects on Circadian Rhythms

Ken Kloes
Inner Fire Yoga Teacher

Most people function on a 24 hour cycle alternating between awake and sleep periods also known as your Circadian rhythm.  Factors such as feeding schedules, physical activity and social interactions can affect this cycle.  However by far, the biggest influence on this rhythm is light.  This is why we naturally have a tendency to sleep at night and function awake during the day when the sun is present.

Your body reacts to stimulus.  When you move into a hot room your heart rate increases, pumping more blood to your outer body parts and skin so that excess heat is lost to the environment and sweating occurs.  You don’t need to think your body into doing this, it reacts all on it’s own to maintain a stable internal environment.

You can think of light stimuli in the same way.  In the morning as the sun rises, light automatically stimulates certain areas of your brain to secrete chemicals that excite your nervous system to become more active and you wake up.  As the sun goes down your brain detects this and begins to secrete chemicals that promote initiation of sleep.  The Circadian drive to sleep is most pronounced in the early morning hours.

If your sleeping environment is bright from a light or television on, window shades open or maybe even the color of your walls, this can have an effect on your sleep, especially in those predawn hours.   Make your room darker with paint or blackout shades creating an inviting ‘sleep cave’.  Eye pillows can even reduce the light reaching your brain through your eyes.  

Managing your light and dark settings where you sleep can have a significant affect on the duration and quality of your sleep.  Something to consider if sleep is a bit elusive during those wee hours of the morning!