Blue light is very, very bad.

Only at night!!!

It is absolutely essential during the day. Sunlight has a high blue content. It is the natural light source that humens are adapted to. It makes you more awake during the day.

If you want good lighting at home, just make it as natural as possible (=> similar to the sun). Bright cool-white light during the day and dimmer, warm light in the evening.

All “white” light will have some blue. The lower the CCT, the less blue it will contain. You’d need to check the datasheet for any particular emitter for its emission frequency range and compare to the frequencies that you consider “blue” to see how much blue spectrum light it emits.

Any monochromatic LED that isn’t blue should contain no blue spectrum light, except for maybe some “green” emitters, such as Cyan. Again, you should be able to check the datasheet to see if it has any blue spectrum light emission. Monochromatic emitters of red, orange, amber, and some greens should be completely blue-light free.

There have been conversations on here and elsewhere about blue-light free nighttime lighting. IIRC, the recommendation is to use just red, orange, and amber lights at night. This works whether you’re talking about human melatonin production or just trying not to attract bugs. But, for most of us, simply using “less” blue light seems to be enough.

This is the bottom - I use flashlights only when it’s dark, mostly when walking the dog just before going sleep. Usually 60-90 minutes.

that is not contradictory, it is about damage to the retina, which is not the topic of this thread

blue light interferes with sleep, by suppressing the hormone that supports sleep, melatonin

blue light is not bad during the day, when we need to be awake, and alert

The intensity is important, too. One of the main studies I’ve found on the effects of light of different CCT’s (where higher CCT’s have more blue present) on melatonin suppression was conducted in a room lit to 200 lux.

That’s not necessarily easy to compare to a flashlight beam where the illumination around you will be uneven, but I think it’s safe to say we’re talking about several hundred lumens of illumination up close, and significantly more further away to cause equivalent melatonin suppression to cause comparable levels of suppression.

Of course, other studies have looked at intensity specifically as a variable, and melatonin suppression continues down to much lower levels, although this study saw on 2% melatonin suppression at 22 lux for 1 hour from ~2700K light.
https://www.researchgate.net/publication/315646147_A_Working_Threshold_for_Acute_Nocturnal_Melatonin_Suppression_from_White_Light_Sources_used_in_Architectural_Applications

Who knew those KMart ‘blue light specials’ were so hazardous?

I have an observation that the modern imbalance of omega 6 to omega 3 (ideally, 1:1) (the well known, by the food chemist’s who are highered by food processing industry, hne byproduct is very bad, especially) will replace the body natural lipid balance, allowing unstable oxidation (leading to atherosclerosis), skin cancer, premature skin aging. Likewise, susceptibility to daylight that our ancestors, before 10,000 years ago would not have been affected by. It does not help that in the last 100 years, formerly industrial oils have become partially hydrogenated to allow some semblance of ediblibilty and stability.

So, take this near sighted article with a gram of fish oil to balance out your modern overdose of “heart healthy” hydrogenated omega 6 vegetable oils.

It is when it alternates with red is when you have to worry

Unless you’re in Chicago…


Anyhoo, interesting article I just came across today. You don’t even have to see blue light for it to kill you dead.

This comment deserves some type of award!

I am rather unhappy with the whole flashaholic community who taught the police how to build low profile light racks. Life was easier in the days when police drove around, roofs adorned with easy to spot, and yummy looking, bubble gumball machines. (Also, I heard they drove at night, slightly lit, by a pilot light, in my parent’s day. )

This library service gives access to a lot of scientific discussion and research papers, and helps people find relevant work.
You can download one at a time free.

Here’s the problem:

At least in Connecticut, I’ve seen troopers just cruising with a steady red light on top. There’s a name for that but I forgot what it is (and I’m still trying to find out).

I thought from vague recollection it may have been “California light”, but searches turned up nothing of interest. Must be something else…

Best I could find was “cruise lights”, but I was (mis?)remembering a location associated with the term.

If you are a mouse, warm colored light may be worse for sleep than blue light

Was under the impression cruiser lights are blue this side of the Mississippi, and red
On the left.

Like radio call signs start with “W” east of Miss, and “K”, west.

Of course, it may be a myth ….

this sounds totally backwards

But the new study, published in Current Biology and led by Dr. Tim Brown, suggests that it’s more natural to look at blue light in the evening and warm light during the day. That may be because natural light is actually bluer during twilight.

my sunsets look orange, not blue… imo there is more blue during the day

next they show that blue light helps mice sleep better

The team of researchers used specially designed lighting on mice in order to test how different wavelengths affected sleep patterns. Blue light proved less disruptive to mice’s sleep than yellow light of the same brightness, according to the researchers.

but wait, mice are nocturnal.
They want to sleep during the (blue light) day. At night, when mice are active, it makes sense that warm light would help them stay awake.

so yes
for a mouse, blue light is associated with sleeping

for a human
blue light is associated with activity during the day
at night blue light interferes with sleep, in humans… maybe not in nocturnal creatures, like some patrol cars… lol

Yep. I don’t regard “BusinessInsider” as a reliable source of scientific or health information.

They spin toward, well, business interests.

kmart sucks.

Sarcasm not needed,
It’s a fact that Blue light can be dangerous for Retina,that depends about intensity and concentration of the emission
Much important is the assuefation that people have for the artificial light.
You will want an ever stronger light

what is “assuefation” supposed to mean?

oh wait

assuefa*c*tion
assuefaction (ˌæswɪˈfækʃən)
n
the condition of being or becoming familiar with or used to something

merriam webster also says it is obsolete

come on - obsolete word, plus mis-spelled - - did anyone else know that?

wle