Morning Ed: Mind & Body {2018.10.01.M}

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Will Truman

Will Truman is the Editor-in-Chief of Ordinary Times. He is also on Twitter.

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5 Responses

  1. Avatar fillyjonk says:

    MB1: given what we’ve known for a while about blue light and wakefulness, I can’t understand why so many devices designed to be used in bedrooms have it as the source of illumination (the air filter I use, the white-noise generator, the radio-alarm-clock I have all use it).

    I can only assume it’s the cheapest. I have to cover some things up (I can’t cover the air filter, it blocks the intake.)

    It doesn’t help that I’m one of those people who needs almost pure dark in order to be able to sleep. (one of my totally-serious questions to a potential partner would be “do you require a nightlight” because if yes, I’m sorry, but we can’t be a couple then)

    I also suspect that the wavelengths in the standard fluorescent tubes cause bad things; maybe it’s not sitting at work or workplace stress that’s making us all sick but the danged lights.

    MB0: what happened in 2013? Social media had already ramped up by then so that can’t be it. But I suspect there’s some cultural thing driving the change-in-responses or change-in feelings in teens. (Though back in the 1980s? I would have answered “yes” to that first question at least occasionally)Report

    • Avatar Aaron David in reply to fillyjonk says:

      As I get older (just a couple years younger than you at 47) I too find the less light the better. However, if I can’t see a clock, I can’t sleep at all. Weird, huh?Report

      • Avatar fillyjonk in reply to Aaron David says:

        yeah, I’m the same about clocks. I have to pop up a couple of times a night and sit up and squint hard (v. nearsighted and usually my glasses are across the room) to calculate how much longer I can sleep. (if it’s within 15 minutes of the alarm, I usually just get up)

        I suppose the future is “Alexa, what time is it” but I tend to be a Luddite about such thingsReport

    • Random factoids:

      LEDs are the preferred type for indicator lights because they are tiny, power efficient, relatively cheap, and mostly indestructible. The expected lifetime is far longer than the rest of the device in almost all cases.

      Pricing by color has always been red the cheapest, then green, then blue. Mostly it’s a matter of materials — compounds that emit shorter wavelengths (blue) are made of rarer materials or have other drawbacks. White LEDs are either multiple LEDs of different colors in a single mounting, or a single LED combined with phosphors, and are priced accordingly.

      Once blue LEDs became common enough, the price thing was a signal: this is a high-quality well-built device because it has expensive blue LEDs instead of cheap red ones.

      One of the obvious solutions — make the LEDs dim when the ambient light level is low — is expensive. An LED is either on or it’s off. Dimming is done by switching the LED on and off rapidly and the human vision system averages things out. “Rapidly” has to be above the rate where people can detect flicker; 120 times per second is generally safe. Fortunately, switching an LED on and off frequently doesn’t shorten its life. The backlight LEDs in my whole house fan controller turn on and off 500 times per second — something over 110 billion cycles since I built and installed it. Anyway, to make the LED react to ambient light level requires at least a sensor, a switch, and a timing source to turn the switch on and off.

      Screen backlights have to be blue-heavy in order to render white. Human eyesight is least sensitive to blue (most sensitive to green).Report

      • Avatar Oscar Gordon in reply to Michael Cain says:

        Screen backlights have to be blue-heavy in order to render white. Human eyesight is least sensitive to blue (most sensitive to green).

        This is why I always set my kindle app to black background & white letters.Report

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