This week, Dr Joseph Mercola posted the following information on his website, based on the work of Neuroscientist Andrew Huberman.

Cortisol is often demonized and considered this bad thing. And, indeed, you don’t want cortisol to be chronically or consistently elevated throughout the day or night. But you do want cortisol to reach its peak early in the day right about the time you wake up. One way that you can ensure that that cortisol peak occurs early in the day, right about the time you wake up, is to view bright light, ideally from sunlight, within the first 30 to 60 minutes after waking.
 
You want to trigger that cortisol increase to occur very early in your day, and you don’t want that cortisol peak to happen later, which is what will happen if you wait to get outside and see sunlight. The reason for this is that you have a set of neurons, nerve cells, in your eye. They’re called intrinsically photosensitive melanopsin cells.
 
Those neurons respond best to bright light, and especially right after waking early in the day, they are best able to signal to a set of neurons that reside over the roof of your mouth called the suprachiasmatic nucleus, which is a cluster of neurons that then sends a huge number of other signals, electrical and chemical, out to your entire body that triggers that cortisol increase, provides a wake-up signal for your brain and body, and sets in motion a timer for you to fall asleep later that night.
 
Huberman refers to viewing sunlight immediately, or within the first hour, after waking as “the most powerful stimulus for wakefulness throughout the day,” which will also help you fall asleep at night.
 
As always, the author adds the caveat that you should not look directly at the Sun. We also advise this, unless you have been taught the correct practices.  He says, “This can be as simple as going outdoors right after you wake up and looking toward — not directly at — the Sun, without sunglasses, and not through a window or vehicle windshield.”