We humans love predictions. Think about the weather for example, knowing whether it’s going to be sunny, rainy, or snowy is super helpful to planning and navigating the days activities, even in this day and age with our tools. Circadian rhythms likely evolved, at least in part because they help us make predictions. It’s a good survival tactic to be alert and active when it’s light out and to sleep and rest when it’s dark, for example.
Circadian rhythms are endogenous rhythms, they exist independently of external cues. These cells in our brains, in the suprachiasmatic nucleus (SCN) are unique to any other cell in the body in this quality. It is other signals in the body, for example a hormone called melatonin that helps to entrain those cells to the light dark cycle of the earth’s rotation. This feedback loop allows us to adapt to seasonal variations.
Last week, our family went and camped out on the Olympic Peninsula. I wanted to try to thread a needle with my two year old and take her to see the tide pools at Hole In The Wall Beach. This was tricky because it is a 4-mile hike and has to be timed to reach the beach at low tide. Suffice it to say, she stayed up past her bedtime, but, she got to see one of Mother Nature’s most beautiful wonders, something I had not planned, the Milky Way Galaxy.
When I pointed it out to her, she said “what’s that?” And it reminded me how disconnected I am from nature, having forgotten about it myself this incredible display of the corner of our universe. Even with black out shades, orange tinted bulbs, blue light blockers, etc, we are surrounded by the lights of our streetlights and cityscape. It is so bright that we are missing out on these beacons of light in the sky that have guided us, helped define us, and taught us who we are for millenia. On average, we sleep about an hour less than our ancestors did 100 years ago.
As we drove back to our cabin, I noticed just how dark it is meant to be. We all slept so well that night.
When is the last time you saw the Milky Way in all of its galactic splendor?