I'm sure we can all agree that color matters. If you're behind the wheel of a car, red means "stop," green is "go," yellow is "proceed with caution" (unless you're a teenager, when it means "floor it.") If you're buying baby clothes, pink and blue mean very different things. And everyone knows what "seeing red" means, while just hearing the words "blue skies" conjures up images of peace and tranquility.
Marketers have made a science of using color to send messages to consumers. McDonalds, for example, uses red and yellow in its logo in part because those colors appeal to children (it's no surprise that LEGOs color scheme is the same). Starbucks uses green because it's calming, and they want their customers to come in, relax, and spend $5 on a cup of something vaguely European sounding. Home Depot's orange background "stimulates activity and is often associated with affordability," according to the company. And nothing says "keeps your house warm in winter and cool in the summer" better than Owens-Corning's pink insulation (they were the first company to ever trademark a color).
Governments, too, sometimes use color to influence behavior. In the 1970s, U.S. Navy prison wardens found that violent inmates became docile when confined in pink cells. And officials in Japan and England discovered that adjusting the color scheme at popular suicide spots (installing blue lights on Japanese train station platforms and painting the Blackfriar's bridge green, respectively) caused suicides to drop significantly.
Okay, so color affects our minds and our moods. But here are two even more important questions: Can color affect us physically? And can color affect us even if we can't see it? The answer to both is a resounding Yes--at least when that color comes in the form of light--a fact backed up by more than 2,000 animal and human studies done over the last 50+ years. The lights/colors with the most significant effects were red and blue. And those effects depend on the time of day and way the lights are applied.
Let's start with blue light. During the day, it's great stuff. Researchers at Harvard found that blue wavelengths improve people's attention, physical and mental reaction times, and memory. However, at night, those same blue wavelengths interrupt our sleep cycles in a big way. Blue lights are commonly found in electronic screens of all kinds (phones, tablets, computers, televisions) and in those energy-efficient, compact fluorescent lightbulbs that we probably bought at Home Depot because their orange sign convinced us that they were cheaper there. What's the problem with losing a few hours of sleep? Plenty. Those same Harvard researchers say that exposure to light at night--specifically blue light---has been linked to several cancers (breast and prostate), diabetes, and obesity. Now here's the most amazing part: Even though they can't actually it, blind people exposed to blue light at night also have trouble falling asleep.
Now on to red. Night or day, people exposed to red wavelengths tend to have more energy and be less depressed than those exposed any other color light. But the real magic of red light happens when it's being directed at various places around your body and skull, places here you can't possibly see it.
Study after study has shown that red light--usually delivered with LED lights tuned to a very specific wavelength--has an amazing capacity to treat dozens of physical conditions, from low sperm count and muscle pain to heart problems and depression. In animal studies, red light has sped up post-stroke recovery times, reduced wound sizes, and regenerated severed or severely damaged nerves. And when focused on specific receptors in the brain, it's as effective as drugs like OxyContin and Vicodin at relieving pain. "It's conceivable that with much more research we could develop ways to use light to relieve pain without a patient needing to take a pain-killing drug with side effects," said Edward R. Siuda, one of the authors of a new study done at Washington University in St. Louis.
In human studies, red LED lights improved more than 40 percent of musculoskeletal training injuries in Navy SEALs, reduced wound-healing time for Navy submarine crews, and reduced by 47 percent the pain associated with childhood cancer patients' oral mucositis, a common--and very painful--complication of chemo and radiation.
If you're interested in learning more about using light to cure (or at least help) what ails you, check with your healthcare provider. Be aware, though, that despite the massive amount of evidence, many traditional M.Ds are less-than-completely enthusiastic. You may have better luck with a local chiropractor.