Dr. David Berson

So this pathway that we're talking about from the retina and from these peculiar cells that are encoding light intensity are sending signals directly into

a center that's surrounded by all of these centers that control autonomic nervous system and your hormonal systems.

The hypothalamus uses everything to control the rest of the bodies.

And that's true of the suprachiasmatic nucleus, this circadian center as well.

It can get its fingers into the autonomic nervous system, the humeral system, and of course, up to the centers of the brain that organize coordinated rational behavior.

Right.

The way this is seen is that if you were to measure your melatonin level over the course of the day, if you could do this, you know, hour by hour, you'd see that it's really low during the day, very high at night.

But if you get up in the middle of the night and go to the bathroom and turn on the bright fluorescent light, your melatonin level is slammed to the floor.

Light is directly impacting your hormonal levels through this mechanism that we just described.

So this is one of the routes by which light can act on your hormonal status through pathways that are completely beyond what you normally would think about, right?

You're thinking about the things in the bathroom.

Oh, there's the toothbrush.

You know, there's the tube of toothpaste.

But meanwhile, this other system is just counting photons and saying, oh, wow, there's a lot of photons right now.

Let's shut down the melatonin release.

Cool.

So, I mean, the first thing to think about is that the vestibular system

is designed to allow you to sense how you're moving in the world, through the world.

Basically, the idea is that if we're just sitting in a car

in the passenger seat and the driver hits the accelerator and you start moving forward, you sense that.