Hackitt and Bodgitt discover Healthy Lighting

Hackitt and BodgittThere has been a lot of talk in the press recently about the colour of lighting and it’s relevance to health.

As far back as 2012, the BBC reported that NASA were to test “space-sleep colour-changing lights” on the international space station and since then there have been a number of articles in the press suggesting that the colour of light at certain times of the day can affect everything from sleep to prostate cancer.

Of course newspapers have also claimed at one time or another that aliens landed on the moon but there is a certain amount of obvious logic in selecting the right colour for the right time of day. Everyone knows that due to atmospheric filtering, the sun appears shifted toward red at night – and it is quite feasible that our bodies respond to those colour changes. No, I don’t follow my star signs!!

KelvinRecently the papers were full of the news (as it there’s nothing more important going on in the world) that our lighting and our various devices such as tablets can affect our sleep and that you should avoid blue light in the evening and that light shifted toward blue in the morning can aid waking up etc. I subsequently found, thanks to readers, a boatload of APPs that do this colour shifting on phones – not a lot of use when you’re trying to take a photo and you’re mobile has gone all red, but probably a good idea when you’re trying to read yourself to sleep.

And with that in mind I set off trawling the web for more information and finally ended up with a set of RGB values which match “colour temperature” in degrees Kelvin. Now I would not be one to claim 100% accuracy here because for that to work with modern LEDs you’d have to be assured that the RGB values you poked into the LEDs would render accurate colours and I doubt very much that this is the case.  However, I’m going to suggest that what I’ve done here is “near enough”.

In our “Hackitt and Bodgitt” board described in the blog article “Home Control 2015” I’ve added a new command to provide white light from RGB LEDs which can be “shifted” by providing a value in degrees Kelvin from 1,000K (very orange-ish) to 40,000K (very blue-ish).  At 6400K you have a perfect representation of the more garish compact Fluorescent lighting and at 1,100K you have a pretty good match for dim candle-light – with all the subtle variations in between.

Hence with a simple command to alter the hue of white lighting, in our case initiated no doubt in a node-red command, we gain the ability to alter the lighting to the time of day.  Now, WHY would you use more expensive RGB lighting as against simple WHITE LED strip in your home of the future? I have a theory about white LEDs and it’s a theory increasingly backed up by anecdotal evidence that white LEDs don’t last as long as some manufacturers might have you believe. RGB LEDs on the other hand don’t seem to have that problem and have the benefit (we’re talking about modern integrated LED, not separate red, green and blue LEDs) of allowing just about any shade of any colour and in this case, any shade of “white”.

I doubt very much that due to this new lighting interest you’ll read “Peter Scargill becomes the first person to live to 150” but you never know, it might just be an aid to better sleeping and that has to be a good thing.

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16 thoughts on “Hackitt and Bodgitt discover Healthy Lighting

  1. What RGB LEDs do you have in mind which are equally bright as the 75 or 100 Watt light bulb replacement LED lights?

    1. ...and which are in the same price range. RGB LED light's are currently much more expensive 🙁

      1. Hi Markus - can't believe it has taken me this long to respond. Well, I've always found the so-called 100w LED replacement lights to have no-where near the output of the original 100w bulbs - but only this week I bought a "corn" light which seem to be the best hope - these look like the multi-tube compact fluorescents and this one had 90 Leds in it on 5 aluminium strips. It cost a fiver in the Chinese store here in Spain on the coast. No doubt B&Q would have charged £10 at least. For around £10, 5M or RGB 12v strip is available and the output of that entire strip more or less matches the single corn light and the price is dropping all the time. Given the flexibility of the strip I think I know which I prefer. The alternative, the white strip - well, to test my heat theory, I put some white strip (uses the same technology as current white LED lights) on aluminium as back lighting for my desk and I've left it on 24-7 - the assumption being that kept cool it would last much longer. I can already see reduced light output from the white after only a matter of a month or so of constant use.

  2. Interesting blog again Peter, as always a pleasure to read!
    I wanted to recommend you some applications: f.lux for Linux, iOS and Windows (https://justgetflux.com/) and Twilight for Android (https://play.google.com/store/apps/details?id=com.urbandroid.lux).
    Both applications provide a red shift of your PC and phone screens. I have been using these for about a year now, and find them very pleasant. I have a bad habit of reading blogs and news on my phone or laptop in bed or just before bedtime. I really think there might be some truth to falling asleep faster with a red-ish screen instead of more blue light.

    1. Thanks to everyone here for your comments.. Indeed Twilight DOES look good and I'm sure the other links will be of great interest to those looking in and taking an interest in this subject. So now we have no excuse not to benefit. I will put my code up when we arrive in Spain this week. Currently sitting in a queue in the pouring rain at motorway services.

  3. Look for Twilight on the Android Play store, it does exactly what you describe above, and it definitely helps me to get to sleep as the last thing I do before lights out is catch up with stuff on my phone.

  4. " anecdotal evidence that white LEDs don’t last as long as some manufacturers might have you believe"
    I have some power led working 10h/days since 2009 and they have lost only 20% of initial power. Some manufacturer don't write real performance, but for the white led in 5050 or other smd format, the problem is more with the users that don't put heasink, and then the led last 3/6month.

    "Now, WHY would you use more expensive RGB lighting as against simple WHITE LED strip in your home of the future"
    With RGB led you'll have a bad CRI because you'll have only 3 wavelenths. RGBWhite is better, or in high power using lime & amber (philips). One big problem with RGB is the lack of efficiency of the green (5-10% compared to 50% on blue (25-30% for non branded )), and with heat color will shift (different response for each color).

    1. Slade... I would guess 99% of LED users have no idea about cooling requirements. I use aluminum strip to get around the heat issue. Re RGB... The serial ones seem to have different green to others and at least in the the ones I have used are brighter. If colour changes can compensate. Flexibility is what does it for me. Any shade of white etc

      1. Aluminium strip is a good start, but the 130mA smd white need big strip.
        Try the RGB but without drivers it's hard to maintain a good white. Depending if you desire colored light (RGB better), or white at different temperature (RGBW), there is a lot of article talking of color shift, color blending, color rendering, and i'm afraid that RGB is not the choosen one...
        For home and white it's easier and more efficient with the RGBW or RGBA in smd.

    2. Most 'White' LEDs are like old-school TV picture tubes (CRTs; go ask grandad) - the LED diode emits short-wavelength energy which hits ('excites') a mix of phosphors, which themselves emit the visible light perceived as 'white'.

      Although the LED diode itself might last tens of thousands of hours, I'm told that the phosphors themselves can 'wear out' at a different rate, and inferior white LEDs might start looking tired or bluish well before the diode itself fails. Just something to watch out for.

      1. Yes Ken that is exactly my understanding and I saw somewhere someone put this to the test and it appears valid - hence my preference where costs allow for using RGB. And indeed assuming "non inferior" LEDs have a better phosphor, I don't see any mechanism to know whether you are buying a superior product or not. I get very sick of seeing ads for boards and parts which are supposedly high quality and better than the Chinese equivalents when I know for a fact all the company has done is buy in the Chinese part for resale.

  5. Peter, there is an interesting article in the latest New Scientist to add to your research (18 Jully). Titled 'Burst of red light turbocharges cells'

    As they point out the healing effects of red light have been known for some time but now they think they know why. Near infra-red (670 nM wavelength) causes the cells mitochondria to produce more ATP which provides the energy. Apparently it's to do with the impact of the light on the surface tension of water near objects. (Which sounds like the mumbo jumbo of homeopathy dilutions changing the nature of water).

    Anyway, I'm sure you can find the article if you are interested and read all about the experiments people are now trying, like shining red light into mice brains via fibre optic cable to see if it helps with Parkinsons...... Maybe you should be patenting your coloured light generator!!

    Simon

  6. Thanks for that Simon, sadly NASA beat me to the idea and no doubt countless others - but at least now people can play with the idea for next to nothing. Thanks for taking the time to follow this up. I'm sure others will also be interested.

  7. I seem to remember you talking about being able to set you WS2812s at various colour temperatures...

    I would be very interested in your formula if you would not mind sharing?

  8. Ok, erm let me look. I ended up using a table of RGB values once I realised I could store them in FLASH memory.

    There you go,

    static const uint8_t ICACHE_RODATA_ATTR kelvin[] = {
    255, 51, 0, // 1000
    255, 109, 0, // 1500
    255, 137, 18, // 2000
    255, 161, 72, // 2500
    255, 180, 107, // 3000
    255, 196, 137, // 3500
    255, 209, 163, // 4000
    255, 219, 186, // 4500
    255, 228, 206, // 5000
    255, 236, 224, // 5500
    255, 243, 239, // 6000
    255, 249, 253, // 6500
    245, 243, 255, // 7000
    235, 238, 255, // 7500
    227, 233, 255, // 8000
    220, 229, 255, // 8500
    214, 225, 255, // 9000
    208, 222, 255, // 9500
    204, 219, 255, // 10000
    200, 217, 255, // 10500
    196, 215, 255, // 11000
    193, 213, 255, // 11500
    191, 211, 255, // 12000
    188, 210, 255, // 12500
    186, 208, 255, // 13000
    184, 207, 255, // 13500
    182, 206, 255, // 14000
    180, 205, 255, // 14500
    179, 204, 255, // 15000
    177, 203, 255, // 15500
    176, 202, 255, // 16000
    175, 201, 255, // 16500
    174, 200, 255, // 17000
    173, 200, 255, // 17500
    172, 199, 255, // 18000
    171, 198, 255, // 18500
    170, 198, 255, // 19000
    169, 197, 255, // 19500
    168, 197, 255, // 20000
    168, 196, 255, // 20500
    167, 196, 255, // 21000
    166, 195, 255, // 21500
    166, 195, 255, // 22000
    165, 195, 255, // 22500
    164, 194, 255, // 23000
    164, 194, 255, // 23500
    163, 194, 255, // 24000
    163, 193, 255, // 24500
    163, 193, 255, // 25000
    162, 193, 255, // 25500
    162, 192, 255, // 26000
    161, 192, 255, // 26500
    161, 192, 255, // 27000
    161, 192, 255, // 27500
    160, 191, 255, // 28000
    160, 191, 255, // 28500
    160, 191, 255, // 29000
    159, 191, 255, // 29500
    159, 191, 255, // 30000
    159, 190, 255, // 30500
    159, 190, 255, // 31000
    158, 190, 255, // 31500
    158, 190, 255, // 32000
    158, 190, 255, // 32500
    158, 190, 255, // 33000
    157, 189, 255, // 33500
    157, 189, 255, // 34000
    157, 189, 255, // 34500
    157, 189, 255, // 35000
    157, 189, 255, // 35500
    156, 189, 255, // 36000
    156, 189, 255, // 36500
    156, 189, 255, // 37000
    156, 188, 255, // 37500
    156, 188, 255, // 38000
    155, 188, 255, // 38500
    155, 188, 255, // 39000
    155, 188, 255, // 39500
    155, 188, 255 // 40000
    };

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