Image via Wikipedia
Before late-neolithic society invented artificial light, we all pretty much needed to rest when the sun went down. There was no effective way (or reason) to be up late at night. You needed to rest to be ready for the next day.
We don’t do that now, and as I write even this, my eyes are beling blasted by the light from a LED monitor. But, I have compensated (slightly) against this by having software control the color temperature of the screen. Wait, color temperature? WTF is that?
Ok, color temperature is a method we devised to compare the light emitted from different surfaces. They’re relative to a blackbody radiator, a really fancy way to say something that absorbs all energy that falls upon it. When it gives off energy, it’s measured by a temperature. The radiation’s temperature is measured in Kelvin (take K × 9⁄5 − 459.67 and you get the Fahrenheit equivalent) If a blackbody begins to radiate energy from it, if we feel “heat” this object. As the temperature increases in temperature, the radiation starts to become more like light. Think of a hot iron being worked on by a blacksmith going from just black metal, to red-hot, and then to white-hot. Light bulbs often will describe themselves as “Soft White,” “Bright White” or “Daylight” in order to avoid teaching you about color temperature, like I’m trying to do here—after all I’m not trying to sell you lightbulbs.
Image by khairilfz via Flickr
What does this have to do with sleep? Ok, we’re getting to that. Think about that hot iron and the blacksmith. The blacksmith works on the iron based on its temperature and knows that the color change reflects the the temperature of the material. There’s a point in all materials that that glows “red” at some point, 798K (or 976F, it’s called the Draper point). The higher the temperature becomes the “bluer” the light becomes. When you get to sunlight, the color temperature is now approaching 5500K or 6500K (depending on which standard you use). Now as the sun sets, it gets dimmer because of atmospheric scattering (making the light more “red’) and eventually dark as the Earth blocks it from our view. So, daylight, while you think it isn’t very “blue”, it much more “blue” than the red light you see at sunset.
Your computer screen and your television can deceive your body because they can produce light “bluer” than ambient light, often far and late into the night. If you’re using your computer, you can delay your body’s response to sunset by hours and disrupt your sleep.
What to do?
Get a color manager program to help this. When the sun sets, it’s color temperature changes from the 5500K–6500K range down to the 3000K range and lower as it gets darker. Your computer can be made to look like sunset for hours after actual sunset and keep your body from believing that its earlier in the day than it actually is.
- http://stereopsis.com/flux/ for PC, Mac and Linux
- http://jonls.dk/redshift/ for Linux
However, this is no excuse to compute into the wee-hours of the morning. You need your sleep. Get it and get enough of it.
