What are circadian rhythms? An article on the University of Utah's site says that: "Living organisms evolved an internal biological clock, called the circadian rhythm, to help their bodies adapt to the daily cycle of day and night (light and dark) as the Earth rotates every 24 hours. The term 'circadian' comes from the Latin words for about (circa) a day (diem)." Circadian rhythms are controlled by "clock genes" that code for proteins that rise and fall in certain patterns over this 24 hour (or so) period of our biological clock. These proteins control things like when we sleep and rest, and when we are awake and active. They also control body temperature, heart activity, hormone secretion, blood pressure, oxygen consumption, metabolism, and many other functions. The master controller of this entire cycle is located in a certain region within the hypothalamus of the brain and communicates with other local clocks throughout the body by sending hormonal signals or even by changing body temperature. It also regulates the secretion of the hormone melatonin by the pineal gland (more on melatonin below).
How is this master clock in the brain and therefore circadian rhythms controlled you might ask? Well, there are specialized cells in the retinas of the eyes of mammals whose job is to detect the presence and absence of light, and assess the overall brightness of light, which is used to reset this clock. Apparently, these cells were just discovered in the last decade. These cells are especially sensitive to blue wavelengths that are present in sunlight, and a lot of the artificial light that we are exposed to today, i.e., computer, TV, iPad, and cell phone screens; and LCD and LED lighting, etc. Other living organisms (bacteria, plants, fruit flies, etc.) have different mechanisms in place for managing their circadian rhythms.
This discovery of these specialized cells is pretty fascinating. Back in the day before electricity, the light people were exposed to came from the sun and perhaps fire, so there was blue-light during the day from the sun, which would stimulate them to wake up and have energy throughout the day. At night, it was dark, so people slept. In today's world, with the amount of light that we are exposed to at night, our circadian rhythms can easily be disrupted. Disruption to this rhythm is associated with various diseases from obesity to depression to even cancer and autoimmune disease. There is a lot of research ongoing exploring this relationship of circadian disruption and disease. One thing they do know is that the increased exposure to blue light suppresses the production of melatonin, which is a hormone that is lower during the day and increases at night, and plays a major role in circadian rhythms.
What does melatonin do for us?
A lot! Here are some more details about melatonin:
- Melatonin is a hormone made (at night) in the pineal gland of our brains.
- It helps control our sleep/wake cycles.
- It is a powerful antioxidant that helps combat inflammation. (Oh, and inflammation is a key player in many of our modern diseases such as cancer, heart disease and autoimmune).
- It has anti-cancer properties by causing cancer cells to self-destruct, and also boosts the production of immune-optimizing substances such as interleukin-2, which helps identify and attack the mutated cells that lead to malignant cancer. Most of the research has been centered around breast cancer.
- Melatonin's precursor is the neurotransmitter, serotonin, and both play a role in regulating and lifting mood.
- There is newer research around its protective role against heart disease, type 2 diabetes and osteoporosis.
- Many other things, as well.
What can we do to help support our sleep/circadian rhythms and melatonin production:
- Use black-out shades in the bedroom
- Install the free f.lux software on your computers, which changes the backlight on the screen from blue light to amber light depending on the time of day.
- Wear amber goggles in the evening up until bed-time. You can buy them on amazon, such as this Uvex brand.
- Use dim red lighting in your house at night.
- Limit screen time at night, and/or stop screen time at least 30 - 60 minutes before bed.
- If possible, don't turn on lights if you wake up in the middle of the night to use the bathroom.
- Get plenty of sunlight during the day and early in the day, and expose your eyes to sunlight early to help reset the clock.
- I am not a big fan of supplementing with melatonin, as it can interfere with the body's own production, but having said that, there are times when it can be supportive, especially for short term use. One should speak with their health practitioner before supplementing.
- There are foods that contain melatonin: tart/sour cherries 🍒 (especially the Montmorency variety) and walnuts are probably the best sources.
University of Utah Genetics Science Learning Center Website. The Time of Our Lives. Retrieved from: http://learn.genetics.utah.edu/content/basics/clockgenes/
Chris Kresser Website. How artificial light is wrecking your sleep and what to do about it. Retrieved from: https://chriskresser.com/how-artificial-light-is-wrecking-your-sleep-and-what-to-do-about-it/
Wired Website. Screens May Be Terrible for You, and Now We Know Why. Retrieved from: https://www.wired.com/2015/03/artificial-light-may-be-unhealthy/
Immune Health Science Website. Foods with Melatonin. Retrieved from: http://www.immunehealthscience.com/foods-with-melatonin.html