Dr. Glen Jeffery

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1,102 appearances 1 recordings 1 series first heard Dec 2025 last heard 1 Dec

Dr. Glen Jeffery’s voice in public audio — every appearance, attributed to the second.

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Huberman Lab · Using Red Light to Improve Metabolism & the Harmful Effects of LEDs | Dr. Glen Jeffery · 1 Dec 2025 podcast

Yeah.

Sunlight extends out almost to 3,000 nanometers.

Just think about it.

Big, big range.

And then that's in the infrared.

And on the other end, the bits that we don't see, the deep, deep blues and the violets, that goes down deeply to about 300 nanometers.

Now, this is a continuum.

We parcel it up because there's bits we see and there's bits we don't see.

You can think about it as a continuous wavelength, and the wavelength gets longer and longer and longer as we go out into the deep red.

So short wavelength lights...

ones just below blue they're very very high frequency they carry quite a kick and that's why when you're sitting in the sun and you get sunburn it's mainly because of those ultraviolet short wavelengths that are present and then you go beyond our visual range beyond 700 and the wavelengths become very very long and they carry a certain kind of energy but they don't carry the kick

So the important point to think of is when you go out in sunlight, you see all these colours, blues, greens, reds, but there's so much out there that you don't see.

And we thought probably you didn't need to be aware of.

But nearly all animals basically see this visual range that we have.

red, orange, yellow, green, blue, indigo, violet, right?

I think the important point to think about is not only what the wavelengths are, but also how body responds to those wavelengths.

So let's bounce back a little bit to, for instance, the sunburn.

we're getting sunburnt because the body is blocking those wavelengths.

Those wavelengths cannot penetrate very far.

So when you're out on a hot, sunny day and part of your body goes pink, it's going pink because it's blocking those wavelengths.

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