Light cycles have been noticeably changing these last several weeks. Naturally, I have enjoyed the pleasant reminder of the approaching equinox. This morning before sunrise, I was reviewing my lecture notes. Part of my focus was outside—the glow of pre-sunrise is happening earlier each day. I heard a sweet cardinal happily chirping. It was a good morning. At the other end of the day, my evening walks have been brighter. The sun is higher up in the sky. Near the end of my walk, I watch the sunset before heading back inside.

I am very intrigued by light cycles, and it is fascinating to ponder how they influence our health. Last trimester, I listened to a podcast by Dr. Andrew Huberman, who discusses various topics in neuroscience. The podcast was about sleep, and he discussed light cycles and circadian biology.

It is important to experience early morning light in order to properly set our circadian rhythm. It is ideal to watch the sunrise everyday with “naked eyes” (no glasses, no sunglasses, not through a window). It takes 2-10 minutes of early morning sunlight exposure to set the clock. As the day progresses, special cells of the eye become more sensitive to light. This means that blue light, bright light, and/or high angle light later in the day can easily stimulate the master clock in our brain. Once it’s stimulated, it results in the suppression of melatonin production. This interferes with sleepiness.

I personally wear blue blocking glasses when the eyes are most sensitive to blue light. I also use low angle, red-hued Himalayan salt lamps in the evenings and mornings. It’s interesting since red light at night does not actually trigger the master clock (think campfires – we evolved with red light at night). Therefore, during the chunks of time I am awake after sunset or before sunrise, I wear red glasses.