“THE UNSEEN BODY” by Jonathan Reisman, M.D.

A young friend of mine was telling me enthusiastically about the book she was reading about sleep and about the importance of sleep in our day-to-day lives.

It was a moment of personal realization when I recalled learning about the circadian rhythm from my M.D., Jonathan Reisman’s book “The Unseen Body”:

“The circadian rhythm–the human body’s cycle of sleeping and waking–depends on PINEAL GLAND, a pea-sized nub of flesh deep down in the brain’s very center.
The pineal gland is the body’s organ of sleep schedules, and a lesser-known endocrinological cousin and nearby neighbour of the PITUITARY.
The hormone melatonin drips from the pineal gland into spinal fluid a few hours before bedtime, and it prepares the body for sleep.

Changing the brain for the circadian rhythm would require exposure to sunlight.
When sunlight hits the human body, virtually all of it stops dead at the skin.
Only through the eyes are the sun’s rays able to sneak past our otherwise opaque covering and penetrate farther inside the body, and this is how its signal reaches the pineal gland. 

Light deactivates the pineal gland’s melatonin secretion, signalling to the body that the time to sleep is over.

And research has shown that, even more than a steady, bright source of light, gradually increasing illumination as the eyes experience during dawn is the strongest signal entraining the body’s circadian rhythm.”

Kindle, 2022