For most of our history, humans lived with the cycle of the sun. We could hunt or travel during the day, and we took shelter at night. That started to change when we discovered fire a few millenia ago. Once we had fire, we could light torches and see what we were doing or where we were going after dark. But that was combersome and sometimes risky, so we didn't do it a lot. Mostly we continued to work during the day and sleep during the night.
We lived in time to our circadian rhythm.
The first significant change to this pattern came with the discovery of coal gas as a fuel that could be brought into our homes and offices and used to make light at the turn of a dial and the flick of a match. That event, the dawn of the gaslight era, happened just before 1800, so it was only a little more than 200 years ago.
The gaslight era lasted a little more than a century, until electricity began to replace gas for lighting around 1900. And that's when we began to really change the way we live. Up until that time, we used light to see things -- our rooms or books or tools, our friends or family, or ourselves in a mirror. We were looking at people and objects illuminated by light. We were not looking at the light itself.
During the 19th century, this began to change too. A number of entrepreneurs, inventors and researchers had been working to develop the magic lantern, which is a direct ancestor of both the slide projector and the motion picture projector.
At first, that work was limited by the poor quality of the available light sources. It took a step forward with the development of the electric carbon arc lamp in 1801, and really took off following the development of the first commercially successful incandescent light bulb around 1879.
from that time on, we have steadily increased the amount of time we spend either looking at lights such a neon tubes and LED displays.
From movies to television to computer monitors and smart phone screens, many of us now spend much of our time looking at light rather than looking at lighted prople and objects. And while engineers work to improve the displays, other reasearchers have been looking into how this might affecting our health.
While the evidence for ill effects directly attributable to looking at projected light remain elusive, there is some agreement that the type and kind of light we expose ourselves to can have an effect on our mood and well-being. This has led, for example, to treating sleep disorders, which are a form of circadian rhythm disorder, with light box therapy. There has also been success with treating our light-absorbing organ -- our skin -- with light with a specific color.
One company has taken this thinking in a slightly different direction. Keeping their focus on the light we look at, especially on our monitors and other screens, they developed programs that change the quality or color, of that light with the time of day, making it bluer while the sun is up and yellower -- closer to the "cool white that's the most popular light bulb color -- overnight. The change is away from having it be blue all the time to adding the shift to the warmer tone adter dark.
We've tried it out, and found it to be pleasant. It may also reinforcing our circadian rhythms, but that is harder to tell. If this sounds like something you might enjoy, or that you think might help you establish a better sleep pattern, check it out.
The program is definitely called f.lux. As of now, there are versions available for Widows, Mac, Linux and iPhone/iPad. No version for Android that I've seen. That may be in the works, but Android already has a screen brightness feature built in. The only problem is that it reacts to ambient light and only adjusts the intensity of the light. It doesn't adjust with the time of day and it doesn't change the color of the light. That's what f.lux is designed to do.