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Blue/White LEDs and melatonin

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This topic contains 2 replies, has 3 voices, and was last updated by  f-nitschke 10 years, 2 months ago.

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  • #443

    gbaddeley
    Member

    Here’s a new post from the Speleonics mailing list. LEDs haven’t been around long enough for their physiological aspects to be studied in caves, but Chris has some interesting ideas. Subscribe to the list to follow the discussion…. Glenn.

    Subject: [Speleonics] Blue/White LEDs and melatonin
    List-Id: Cave Electronics Discussion Group <speleonics.lists.altadena.net>
    List-Subscribe: <http://lists.altadena.net/mailman/listinfo/speleonics&gt;

    White LEDs are a natural for cave lights… right?

    This article describes some potential problems with blue LEDs. It
    seems that our eyes have a blue-light receptor, separate from our
    vision system, that tells our bodies to stop making melatonin. And it
    is sensitive to a narrow range of blue light–exactly what blue LEDs
    put out.

    http://texyt.com/bright+blue+leds+annoy … alth+risks

    White LEDs are blue LEDs plus an orange phosphor. So they still put
    out a strong peak of pure blue.

    I wonder whether cavers who need peak performance underground,
    especially on multi-day expeditions, could use this effect? Perhaps
    they could use white LEDs to wake themselves up, and switch to orange
    LEDs at the right time in their circadian cycle to allow themselves to
    sleep?

    The article also points out that blue light is not focused as well as
    other colors (shorter focal length), and that blue light appears
    brighter in dim light conditions (our rods are more sensitive to
    blue-green colors). The combination of the two can lead to bad
    headaches as the eyes strain to adjust their focus. So white LEDs may
    be harder to tolerate at low intensities where the rods take over and
    things start to go monochrome.

    Finally, the pupil constriction signal is strongest from blue light. I
    don’t know if that’s all blue colors, or just the narrow band of blue
    that LEDs put out.

    So, here’s my theory: for bright light when you want to stay awake,
    white LEDs may work well. For dim light, or before and during sleep,
    use red or orange LEDs. Fluorescents and incandescents should be
    halfway between orange and white LEDs: they include bluish light, but
    not the concentrated spike of pure blue color that white LEDs have.

    Some cavers build lights out of red, green, and blue LEDs, rather than
    using white. They might want to switch off the blue LEDs entirely on
    the "dim" settings.

    Chris

    Chris Phoenix cphoenix@CRNano.org
    Director of Research
    Center for Responsible Nanotechnology http://CRNano.org

    #1178

    Anonymous

    [quote:3o0m6agk]So, here’s my theory: for bright light when you want to stay awake,
    white LEDs may work well. For dim light, or before and during sleep,
    use red or orange LEDs. Fluorescents and incandescents should be
    halfway between orange and white LEDs: they include bluish light, but
    not the concentrated spike of pure blue color that white LEDs have. [/quote:3o0m6agk]

    This is interesting. Would this theory apply to lengthy sleep within a cave (ie. wanting a good 8 hours) or any type of sleep? I’ve successfully been able to have maybe 30 minute naps in a cave with the LEDs from my headtorch shining directly above my face.

    #1179

    f-nitschke
    Member

    Thanks for the link and the excerpt, Glenn. Interesting reading, and you’ve spurred my interest to read more.

    I can’t say that I’ve sufficient experience regarding long time exposure to LED lighting underground although I’ve noticed a difference in my focal range depending on LED, incandescent or combination – and always thought it as much to do with the colour of the light as its intensity. Well, there you go.

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