In the last 20 years, advances in technology have dramatically improved the efficiency of our lighting options, from bulbs to mobile phones to computer screens. Ever since humans figured out the whole fire thing, we’ve been advancing at the pace of our ability to create useful artificial light. Here’s a quick rundown of the last 5,000 years of light, if you’re just tuning in this century: 
- 5,000 years ago: Candles invented, being awake after dark surges in popularity.
- 240 years ago: The first fixed oil lamps make interior lighting way better, and safer too.
- 150 years ago: Thomas Edison, and other electrical engineers, have the first “light bulb” moments, resulting in a pretty famous invention.
- 100 years ago: Electricity becomes the norm in the industrialized world, and the first light-emitting diodes (LEDs) are invented.
- 30 years ago: NASA funds the first clinical studies of red light-emitting LEDs for biological uses.
- 15 years ago: Shuji Nakamura invents blue LEDs, the latest major lighting innovation.
Not all light is created equal. Blue light is one of the highest energy and most efficient wavelengths within the light spectrum. Harnessing it for everyday lighting has been such a big advance that Shuji Nakamura won the 2014 Nobel Physics Prize for pioneering it. Blue light can have a lot of health benefits for humans, but in this case, too much of a good thing becomes a bad thing.
This article will give you a quick overview of blue light: what it is, how it works, pros, cons, and the best ways to limit the darker side of modern blue light advances.
What’s Blue Light?
Like red light, blue light is part of the visible light spectrum, where it ranges between approximately 380nm & 500nm, making it one of the shortest, highest-energy wavelengths. In natural sunlight, blue light is always present with red light, leading to numerous therapeutic effects.
Blue light isn’t just in sunlight though; it’s everywhere, including the screen you’re reading this on right now. In fact, TVs, computers, and cell phones use mostly blue light for their screens. Because of its efficiency and low cost, blue light has also become the dominant wavelength for everyday home and commercial lighting. Fun fact: 95% of the energy from blue wavelengths is converted to light, leaving only 5% wasted as heat. 
Blue light isn’t all good news though. Increasingly, better LED technology has allowed us to remove the red and near infrared (NIR) wavelengths from many of our primary light sources. This increases efficiency because of a higher concentration of blue wavelengths. For energy use and savings, this is a classic win-win scenario. But our bodies, and our sleep, may be the unexpected losers.
In natural sunlight, blue wavelengths are always together with red wavelengths, so our bodies, long ago, evolved to metabolize the two together. But when blue is present without red, like in most of our modern environments, there are possible negative ramifications. Next, we'll break down both the potential positive and negative health effects of excess blue light.
Blue Light and Your Health: PROs
If you’re trying to make the most efficient light bulb or computer screen, you want as much blue light as possible. But when it comes to your health, remember, blue always goes better with red. The blue light you get from natural sunlight can be good for you because it comes with the full light spectrum, including therapeutic red and near infrared light. Natural blue light is especially important for regulating your vital circadian rhythm, the term for your body’s asleep-awake cycle.
To explain, let’s jump to your brain. The suprachiasmatic nucleus (SCN) is a little part of your hypothalamus that acts as the body’s master alarm clock.  The SCN controls your sleep cycle, and when it gets a healthy dose of blue and red light during daylight hours, you sleep better. You’re also more alert, and have better hormone levels, body temperature, immune function, and digestion.  If you stay inside too much and don’t get enough natural light during the day, odds are your sleep isn’t as well regulated and you’re more tired than you should be.
Blue Light and Your Health: CONs
With all due respect to Eiffel 65 and their 1999 hit single Blue (Da Ba Dee), too much blue light is bad for your health. It’s great during the day when your body expects it, and helps your brain communicate effectively to the rest of your body. But now we live in a blue-lit world where our electronics and home lighting hit us with blue light at all hours. Our bodies just weren’t designed for round-the-clock blue light.
Getting blue light at dark times of the day messes with our body’s natural cycles. That’s why watching TV, or scrolling on your phone right before bed, can make it harder to sleep. Your body is getting all that blue light and the color is essentially telling your brain it’s the middle of the day, right before you try to shut down for the night. Your SCN doesn’t know, or care, that you have to wake up early for work tomorrow, it’s partying like it’s noon when you stare at a bright screen in the dark before bed. 
In addition, we're learning more about how melatonin is the hormone responsible for regulating the sleep/wake cycles in the brain. Not surprising, blue light directly inhibits our body’s melatonin flow, hurting our ability to fall asleep, in addition to negatively impacting the quality of the sleep we get. [4,5] Poor sleep over time can become a chronic condition, and exhaustion can make it much harder to overcome other health challenges. There are so many people who don’t get enough sleep and feel the negative consequences every day. Most of these folks have no idea that the artificial blue light they’re surrounded by all the time is one of the biggest hurdles to restful sleep.
What Can You Do About Harmful Blue Light Exposure?
Feeling blue from poor sleep and lack of energy? Here are some practical ways you can cut back on your artificial blue light exposure and improve your body’s natural rhythms.
- Block Blue: Find some blue light-blocking eyewear and software for your devices that limits your blue exposure. 
- Add Red: Lower color temperature lighting like amber and red wavelengths are good choices after dark. The Joovv is an ideal alternative for nighttime lighting.
- Go Darker at Night: After the sun sets, keep your surroundings darker so your body can wind down before bed. Reading real print is better than a screen. Blackout window coverings and sleep masks work for many people because they block out unwanted light at night.
- Catch the Sunrise: Romantic sunsets get all the love, but a great way to reset your circadian rhythm is to get up early and watch the sun come up. 
Conclusion: Red > Blue When it Comes to Health
Blue light has done amazing things for our lighting and electronics, but our bodies and sleep cycles pay the price when we overload with artificial blue wavelengths at the wrong times. While natural blue and red light from the sun have numerous health benefits when absorbed together, blue light by itself is keeping us up at night and causing those bags under our eyes in the morning. The good news is you can easily cut back on artificial blue light and add more healthy, red light to your life, especially with something like a full-body Joovv.
Scientific Sources and Medical References:
 Timeline of Lighting Technology, Wikipedia
 The Advantages of LED Lights for the Environment, Sepco
 Moore, R. “Suprachiasmatic nucleus in sleep-wake regulation” Sleep Med. 2007, Dec 8 Suppl, 3:27-33.
 Gooley, J., Chamberlain, K., Smith, K., Khalsa, S., et al. “Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans” J Clin Endocrinol Metab. 2011, Mar; 96(3): E463–E472. doi: 10.1210/jc.2010-2098
 Brown, RL & Robinson, PR. “Melanopsin: shedding light on the elusive circadian photopigment” Chronobiol Int. 2004 Mar; 21(2):189-204.
 Burkhart K & Phelps JR. “Amber lenses to block blue light and improve sleep: a randomized trial” Chronobiol Int. 2009 Dec; 26(8):1602-12. doi: 10.3109/07420520903523719
 The Physics of Sunsets, ScienceBlogs