We've created unnatural environments that we are not evolutionarily adapted to. This causes us many problems including obesity, metabolic syndrome, and assorted addictions. Another item on the list: blue-shifted bright lights at night might be boosting depression, impairing learning, and increasing stress hormones in the blood.
For most of history, humans rose with the sun and slept when it set. Enter Thomas Edison, and with a flick of a switch, night became day, enabling us to work, play and post cat and kid photos on Facebook into the wee hours.
According to a new study of mice led by a Johns Hopkins biologist, however, this typical 21st- century scenario may come at a serious cost: When people routinely burn the midnight oil, they risk suffering depression and learning issues, and not only because of lack of sleep. The culprit could also be exposure to bright light at night from lamps, computers and even iPads.
"Basically, what we found is that chronic exposure to bright light -- even the kind of light you experience in your own living room at home or in the workplace at night if you are a shift worker -- elevates levels of a certain stress hormone in the body, which results in depression and lowers cognitive function," said Samer Hattar, a biology professor in the Johns Hopkins University's Krieger School of Arts and Sciences.
Of course, we might not be like mice in this regard. But the applicability of these results to humans seems very plausible.
Pay attention to Kelvin numbers when buying bulbs for evening use. Got a room you read in? Go for 2700K at most. I just checked a lot of light bulbs I've got in a closet and most do not have Kelvin numbers. Though some are at 2700K. Looking at an online light bulb site it appears CFL bulbs below 2700K are rare. But if you look for high pressure sodium bulbs you can find them in the 1900k to 2200K range.
Dr. Hattar also says go for less bright bulbs in the evening.
"I'm not saying we have to sit in complete darkness at night, but I do recommend that we should switch on fewer lamps, and stick to less-intense light bulbs: Basically, only use what you need to see. That won't likely be enough to activate those ipRGCs that affect mood," he advises.
What would be handy: A way to record 2 color settings on a PC and then shift between them depending on what you are doing. Go to red/black only for evening text reading.
|Share |||Randall Parker, 2012 November 18 05:26 PM|