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Wednesday, November 22, 2006

Book Review - Lights Out: Sleep, Sugar, and Survival

I finished reading Lights Out: Sleep, Sugar, and Survival for the second time recently. If you care about health and nutrition, this book is a must-read. It is one of my favorite nutrition books, right up there with Protein Power Lifeplan and The Paleo Diet. The basic premise of the book is that our use of artificial lights has disrupted our connection with the seasonal and circadian light cycles of the earth. Until humans discovered methods of controlling fire, we were reliant on the sun for light, just as all wild animals are. However, the real kick in the pants for us came in the 20th century when artificial light became cheap and widespread. We are now in control of "the sun".

So why does this matter? The human body, just like the body of all animals, is finely tuned to the amount of sunlight that hits the earth during the day. The basic formula is this:
- Long days = summertime
- Summertime = winter is coming
- Winter = famine
- Famine coming = feast now to store bodyfat
There are alot of hormonal workings going on that drive those things, from insulin to melatonin to seratonin and dopamine, but that's the gist of it.

When you look outside your window in November, you see darkness, usually by the time you arrive home from work. Fifty-thousand years ago, we would've gone to bed soon after the sun went down, even though we had fire to light the darkness. Keeping a fire going would've been costly in terms of energy expenditure to find the materials to burn. Now we stay up four, six, even eight hours after the sun has set. While we should be laying down, creating melatonin which cascades into prolactin production, we are wide-awake, staring at the TV or computer screen, keeping ourselves up with bright lights. It all boils down to light toxicity which brings on metabolic disorders, including depression (from improper seratonin/dopamine production), heart disease, cancer, dysbiosis of the gut, and any number of other maladies. And because our bodies judge the "days to be long" (it's "constant summertime" in the modern world!) from all the light hitting the skin, we crave carbohydrates, which causes insulin resistance so that the incoming calories can be stored as bodyfat. It is a survival mechanism that is no longer needed.

Read this book! Yearly! And go to bed earlier. The authors of the book recommend 9.5 hours per night in a completely dark room. Completely dark means completely dark, not mostly dark. That means cover your windows with blinds, shades, curtains...whatever it takes to keep the outside light outside. And cover up your alarm clocks and blinking LEDs. You may miss your favorite TV show, but you'll feel better, look better, and have a much easier time eating better.