Why We Sleep: Unlocking the Power of Sleep and Dreams

by Matthew Walker

For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about one hour.

Caffeine has an average half-life of five to seven hours. Let’s say that you have a cup of coffee after your evening dinner, around 7:30 p.m. This means that by 1:30 a.m., 50 percent of that caffeine may still be active and circulating throughout your brain tissue. In other words, by 1:30 a.m., you’re only halfway to completing the job of cleansing your brain of the caffeine you drank after dinner.

World Health Organization has officially classified nighttime shift work as a “probable carcinogen.”

World Health Organization now labels the lack of societal sleep as a global health epidemic.

“my mind is made up, don’t confuse me with the facts.”