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  • Sophia Kamveris, MS, RD

The Power of Light on Your Body Clock

In New England, it seems like our energy levels are often dictated by the weather. Summer days filled with more sunlight hours allow people to enjoy more outdoor time. It’s not as though we added hours in the day, but they seem longer, so we pack in activities like trips to the beach, baseball games, BBQ’s, and outdoor exercise. While we can!

I caught up on some light summer reading and topped it off with some heavy science as I prepared for my fall newsletter. I just finished reading a book called The Circadian Code, by Satchin Panda, PhD. I now have a better understanding how it ties into how we function and why when we eat is so important. To the newbies, the word circadian is derived from the Latin: circa means “around or approximately,” and diem means “day.” So, when we talk about circadian rhythm, we are referring to the biological processes of all living organisms that occur over the course of one day.

It was eye opening for me to learn the importance of light. The author reports that the average worker spends 87% of his/her time indoors. And when we do get outside, it’s in the latter hours of the day when light is not at its peak. Unfortunately, skin cancer warnings also keep people shielded from the sun. He notes that it’s critical for our brains to have exposure to light for it to function at its fullest capacity. I can only address the work and commuting crisis in the Boston area, but I suspect all urban cities are feeling the pinch of being stuck in cars, underground subway stations, and concrete buildings for most of the day. Up at 5AM and home at 7PM… I hear it all the time in my practice. When do people see the sun??

We know that sunlight activates vitamin D production in our bodies but light also affects how our hormones work. Natural light in the morning tells the body to produce the stress hormone, cortisol, which gets us out of a groggy state of sleep and gets us going. At the same time, there’s a light-sensing protein in your eyes, melanopsin, that tells the body to stop producing the sleep hormone, melatonin, that rises a few hours before you sleep. If you recall from a previous article, blue light emitted from electronics (TVs, tablets, smart phones, LED bulbs) suppresses melatonin. I can’t stress enough the importance of disconnecting from electronics two hours before bedtime, or invest in filters that block out the blue light. Most smartphones or computers have night shifting options where you can dim the lights on your screen.

Dr Panda recommends that we get at least one hour of daylight exposure a day; preferably in the beginning of the day. He encourages kids to get sun time in before school to energize their brains, but I suspect that may be an impossible feat for kids that get bussed and/or are not early risers. Sadly, as we return from vacations and school is starting, we will experience shorter sunlight hours.

Of interest, as we head back to work and school, I learned that even our attention span has a circadian component to it. We are the most attentive during day hours when the body and brain are most rested and notes that our brains work best between 10AM and 3PM. When we experience sleep deprivation and poor eating habits, we are vulnerable to a lack of focus and clarity. By the end of the day, out body is preparing us for sleep, so we are not as attentive at that time. Nature has groomed our bodies to be day people versus night owls, yet busy work schedules and hectic lifestyles mean we buck the efficiencies of our primal system. All too often, many end up relying on caffeine or medication to keep them up, or to stay focused.

There’s a lot more great information in the book. It is very science based, so it may take awhile to get through. I am continually fascinated how our bodies work and how we need to respect and treat it well to achieve a healthy body and mind. Setting routines of getting up and going to bed at the same time every day is a good first step in maintaining a strong circadian rhythm. It sets the tone for how you function throughout your day much better than that cup of joe!


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