#741 Sleep Q: How Little Light Is Too Much?

A: Not a Lot!

In our last +1, we talked about some fascinating research from Matthew Walker’s BRILLIANT (!) book Why We Sleep.

Recall that reading via iPad at night suppressed melatonin released by over 50%. (Print books for the win!!)

That data kinda begs the question as to WHY iPads have that effect.

The very short (and oversimplified) answer goes something like this: We evolved over millions of years to align our biological rhythms with the rhythms of the sun.

Those rhythms are known as circadian rhythms. (As we’ve discussed, circadian means “around a day.”)

Now, there’s a tiny (!) part of our brain called the suprachiasmatic nucleus that helps regulate our circadian rhythms. That little guy is SUPER sensitive to light (particularly artificial blue light emitted from digital devices like smartphones and iPads).

Which makes sense when you think about it. For millions (!) of years, the presence or absence of light was a very reliable indicator of whether our bodies should be in “awake” mode or “sleep” mode.

Then, in the evolutionary blink of an eye, 100 years ago we harnessed the power of generating artificial light and… well, let’s just say that our suprachiasmatic nuclei didn’t get the memo that they should ignore all the artificial light and… well, let’s just say that the ramifications of that shift and the resultant diminution of sleep has had disastrous effects on our health and mood and all things good.

As Matthew says: “This silent sleep loss epidemic is the greatest public health challenge we face in the twenty-first-century in developed nations. If we wish to avoid the suffocating effects of sleep neglect, the premature death it inflicts, and the sickening health it invites, a radical shift in our personal, cultural, professional, and societal appreciation of sleep must occur.

For Today, I want to shine a light (🔦) (😜) on just how little artificial light (fires are ok 😉) throws our little suprachiasmatic nuclei off.

Here’s how Matthew puts it: “What of a petite bedside lamp? How much can that really influence your suprachiasmatic nucleus? A lot, it turns out. Even a hint of dim light–8 to 10 lux–has been shown to delay the release of nighttime melatonin in humans. The feeblest of bedside lamps pumps out twice as much: anywhere from 20 to 80 lux. A normally lit living room, where most people reside in the hours before bed, will come in at around 200 lux. Despite being just 1 to 2 percent of the strength of daylight this ambient level of the incandescent home lighting can have 50 percent of the melatonin-suppressing influence within the brain.


So, if you’re playing the Optimizing Marginal Gains Game, iPad reading at night is reduced/eliminated and print books are in for the win.

And… You may want to consider leaving your normal lights off at night and going exclusively with orangey-colored night light kinda lights to make sure your suprachiasmatic nucleus and its melatonin flow are Optimized. (That’s how we roll at the Johnson family!)

Of course, you can also start rocking some blue-light-blocking glasses if you’re really feeling it. 😎

And if you REALLY want to go all in, I suppose you could just go with fire light from now on. lol.

That’s Today’s +1.

Low fives to you and your suprachiasmatic nucleus!

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