Human beings evolved with natural light patterns. Our bodies respond differently to the rising sun, the light at full noon and the darkness of night. For some time, researchers have known that our internal circadian rhythms are modified by the eye’s exposure to light, whether it comes from the sun or from LED lighting.
Maintaining a natural wake/sleep cycle with exposure to sunlight during the day boosts the immune system and improves overall health. Accordingly, exposure to unnatural light patterns can result in negative health outcomes, such as depressed mood and sleep disorders. Recently, the American Medical Association found a potential link between artificial night lighting and breast cancer.
To come to this conclusion, AMA researchers reviewed medical literature on how exposure to artificial lighting at night impacts health. In this case, artificial lighting would include computer screens, television sets and incandescent light bulbs – any light that has a high intensity in the blue end of the light spectrum. This blue-spectrum light is abundant when sun is at its peak, so it makes sense that exposure to it would throw off our internal clocks.
The brain produces and releases different neurochemicals according to light exposure. Exposure to blue-spectrum light (think sunlight) increases production of dopamine, for instance, which promotes alertness throughout the body. Lack of blue-spectrum light, on the other hand, signals to the body and mind that it’s time to sleep. When blue light is blocked, chemicals such as melatonin are released. Most people know that melatonin helps humans fall and stay asleep, but it is also believed to exact an anti-cancer effect on cells.
At this point, researchers can’t say for a fact that exposure to artificial light late at night causes cancer. The AMA research council suggested further multidisciplinary research on this issue, so we’ll know more in the next few years. Still, there is ample evidence that nighttime exposure to artificial light is harmful, so it makes sense to limit your late-night computer and television time so you can at least enjoy restful sleep.
As we better understand light exposure and human wellness, LED lighting could provide a prescription for improved health. LED lights, unlike incandescent bulbs, produce a single wavelength of light rather than a full spectrum. When designing LED lights, manufacturers can select what tones and wavelengths the bulbs should emit. (This is possible thanks to the fact that digital semiconductors power LED lighting.) As researchers establish how different colors of light impact human mood and health, engineers are creating LED lighting systems to stimulate preferred behavioral outcomes. The new LED lights in the Boeing 787, for instance, are designed to reduce jet lag by tweaking passengers’ circadian rhythms.
Indeed, we can expect to see “biological specific” LED lights hit the market within a couple of years. Until then, here’s a trick you can use to maintain melatonin production throughout the night. If you wake up in the wee hours, avoid turning on regular lights, as doing so will immediately slash your body’s production of melatonin. Instead, use a red flashlight to light your way. Red-spectrum light doesn’t trigger circadian responses and won’t stop your melatonin exposure, so you should have an easier time getting back to sleep.