We tend to think of light as being associated almost exclusively with vision. However, light enters your body, as energy, through your eyes, skin, and scalp. It influences your circadian rhythm, metabolism, the composition of your blood, cells, and proteins and is a catalyst for many chemical reactions which play crucial roles in vital bodily functions.
The human body’s reaction to light is more than skin deep. Surprisingly, the inside of your body is not a dark cavern. Research has shown that our bodies are filled with numerous light chemical switches and amplifiers. Deep inside your cells photons flash and energy is transferred in colorful exchanges.
It’s well-known that plants use energy from sunlight to make food, but we are discovering that plants aren’t the only living beings that have a complex relationship with and need for light. Even single cell organisms without eyes have light-sensitive molecules, similar to the ones in our retinas, that absorb light energy which directs behavior and processes.
Using light as medicine has been around for decades to promote wound healing. More recently light is showing success in treating various conditions, ranging Multiple Sclerosis and cancer to depression and Alzheimer’s and Parkinson’s.
How Light Sets Your Circadian Rhythm
The circadian system in animals and humans is close to, but not exactly, a 24-hour cycle and must be reset on a daily basis in order to stay healthy and in sync with the environment.
When light hits light-sensitive cells in the brain, it triggers activity in an area of the hypothalamus which stimulates the pineal gland to produce the hormone melatonin. Your body makes the highest amount of melatonin at night for about 12 hours and then tapers off during the next 12 daytime hours.
The intensity and wavelength of the light determine how your biological clock is affected. Studies have found that the blue and white light spectrums impact the circadian system them most. Many biological functions are dependent on the circadian rhythm. The timing of timing of the light is also important to ensure that the circadian system is in balance.
Science has shown that out-of-balance circadian rhythms can have a substantial negative impact on your behavior, body, and brain. These findings suggest that the modern, indoor, round-the-clock lifestyle, made possible by electric lighting, could disrupt metabolism and interfere with learning in ways that are only just beginning to be understood. Disrupting circadian clocks has been shown to affect many things from short-term memory, creativity, and learning to weight gain/loss, immune system strength, and cancer.
Optimizing Your Circadian Rhythms
To ensure optimal function of your natural circadian rhythm means having consistent, regular exposure to bright light during the day, minimizing your exposure to light in the evening, and sleeping in total darkness at night. These sleep habits would optimize melatonin production and set circadian rhythms.
Unfortunately, over-exposure to the wrong kinds of lights in the evenings and under-exposure to bright light during the day is typical of the modern lifestyle. Most of the incandescent and fluorescent lights used indoors emit very poor quality light. Your body needs the full-spectrum light for optimal functioning. If you’re stuck in an environment without natural light for most of your day, getting more full-spectrum light during daylight hours can help avoid disruption of circadian rhythms.
The reverse is also true for the evenings. Ideally, once the sun sets, you would want to reduce the overall amount of light you’re exposed to. Equipping your house with low blue lights that you use in the evenings, in your bedroom, for example, can help. Low blue light bulbs emit predominantly amber light that doesn’t suppress melatonin production.
TVs, smartphones, and computers also put off a lot of blue light, which will inhibit melatonin production if used at night. Ideally, you want to shut these devices off once the sun goes down. We all know that’s not practical or possible most of the time, but you do want to limit their use, especially right before bed.
When you do go to bed, make sure your environment is as dark, noise, and interruption-free as possible. Sleep is the number one most important factor in brain health. So, make it count. Even though you may be getting an adequate quantity of hours, if it’s not quality sleep, your brain can’t fully run through the sleep cycles and suffers.
What You Can Do to Balance Your Brain’s Exposure to Light
Besides needing bright light to set your circadian rhythms, it influences your body’s production of serotonin. Serotonin does many different things in your body and plays an important role in your mood, emotions, and mental function. You can keep your circadian rhythm in balance and optimize serotonin production by getting more bright light.
The simplest way to get more bright light is to spend more time outside, especially in the morning, if you can. Most people in Western societies spend most of their days indoors, which essentially puts us in a state of “light deficiency.” According to the article, How the Cycles of Light and Darkness Affect Your Health and Wellbeing:
In terms of light intensity, outdoor light is far more intense than indoor light. Light intensity is measured in lux units, and on any given day, the outdoor lux units will be around 100,000 at noon. Indoors, the typical average is somewhere between 100 to 2,000 lux units—basically two orders of magnitude less.
Studies have shown that supplementing with light daily is useful in treating a variety of these sleep disorders, seasonal affective disorder (SAD), jet lag, and circadian rhythm disorders. Using a light box, usually 30 to 60 minutes per day, can be an effective means of increasing your intake of full spectrum light, There is even a LED headset available which gets light directly to your brain via ear buds in the ear canal in just 12 minutes per day.
Decrease Bright Light at Night
Another option is to strategically equip some of the lights in your house with low blue light bulbs to decrease your exposure to bright light at night and minimize disruption of melatonin production.
Here’s a wonderful animation explaining circadian rhythms.