Did you ever consider that staring at your cellphone at night before bed may have the same effects as eating too much sugar?
What is blue light?
Sunlight comes in all different colors (red, orange, yellow, green, and blue) and not all colors of light have the same effect. The amount of energy provided by the light ray is dependent on wavelength. Light rays with a longer wavelength contain less energy and those with a short wavelength give off more energy.
Blue wavelengths, which have shorter wavelengths contain more energy. 
Blue Light is Everywhere
We get most of our exposure to blue light from the sun when we are outside during the day. But, with the increasing abundance and usage of electronics, we are getting increased amounts of blue light through the day and evening.
Smartphones, tablets, laptops, computers, and other electronics give off a significant amount of blue light. Even though the amount of blue light emitted by these devices is only a fraction compared to the sun, the amount of time people are spending in front of these devices is having adverse effects on their health.
Benefits of Blue Light
Blue light does have it’s benefits… when exposed to it during the daytime. Blue light boosts attention, reaction times, and mood. And it can also increase memory. In fact, the light sources used to treat Seasonal Effective Disorder (SAD), emit a significant amount of blue light. In addition, exposure to blue light during the daytime hours also been proven to help regulate circadian rhythm — the body’s natural wakefulness and sleep cycle.
Blue Light Exposure is Like Sugar
According to Harvard Health, similar to a diet high in refined sugar, there may be a link between exposure to blue light at night and chronic disease (cancer, diabetes, heart disease, and obesity).
How is that possible?
Blue light contains more energy that the other color light rays, hence the benefits stated above. Because of this energy, blue light suppresses the secretion of melatonin, the hormone regulates sleep.
A Harvard study put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, putting them into a prediabetic state. The levels of leptin, a hormone that leaves people feeling full after a meal, went down.
As noted in Physiology & Behavior, “Our circadian rhythm is also influenced by the nightly secretion of the hormone melatonin, and light at night inhibits the production of this sleep-promoting hormone. That, in turn, could affect the hormone leptin, otherwise known as the satiety hormone that signals your brain that you are full, so when this hormone messaging is thrown off, you gain weight.”
How Much Screen Light is Too Much?
“As low as 5 lux of light [the unit of measure scientists use for light] at night can disrupt your circadian rhythm,” Dr. Kathryn Russart stated in EndocrinWeb. She added, “To put that in perspective, a TV or a cell phone held about a foot away from your face can emit 40 lux. A full moon gives off about 2 lux.”
How to Improve Your Health
- Get outside during the day! Expose yourself to lots of bright sunlight, which will boost your ability to sleep at night, as well as your mood and alertness.
- If you use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night.
- Avoid looking at bright screens beginning two to three hours before bed.
- Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin.