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

I don't know that cutoff point, but there's an enormous difference between the light produced by a flashlight and sunlight.

Sunlight is an enormous broad spectrum.

And that flashlight is just a little window of light that happens also to be present in sunlight.

Now, I think the two situations are probably incomparable, right?

And I'm not going to spend whatever is left of my career hunting that down.

We know, and I think this is a global concept I've got, which is that we can do much with single wavelengths of long wavelength light.

like a flashlight, which is 850 or 610.

We can do a lot, but we can never do the same as you can get from sunlight.

But you can't do those tight, controlled experiments with sunlight that I can do much more easily with specific wavelengths.

I think the important point there is that long wavelength light gets scattered by water.

It gets absorbed and scattered by water.

So on a winter's day, we've got a cloud, and that cloud contains water.

There will be an attenuation of the longer wavelength light.

It won't be vast, but there will be an attenuation.

But it will start coming at you in different angles.

So when you're walking on a sunny day and you're walking down the road, sun's in front of you, you feel warm on your chest when you've got clothes on.

And that's the longer wavelength light doing it because it's relatively focused.

On that winter's day, you're still getting a lot of long wavelength light, but it's coming at you in a lot of different angles and it's slightly attenuated.

So my argument, which is the new mantra of the lab to some extent, is get a dog.

Get a dog because you'll have to go out in daylight two or three times a day.

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