Skimping on sleep weakens the immune system, makes us more pessimistic, and increases our risk of gaining weight, among other recent findings. Yet more people than ever before are increasing their pace of life by staying up later and getting up earlier. More than a third of adults in the United States get less than seven hours of sleep each night, which may be one reason why drowsy driving takes the lives of 800 Americans and injures 44,000 annually (based on 2013 statistics).
Considering that adult humans typically spend up to a third of their lives in a subconscious state, researchers know surprisingly little about sleep’s main function in our lives—other than preventing drowsy driving. Yet “research conducted over the past twenty years has finally begun to provide at least a partial explanation for why we must sleep,” Robert Stickgold writes in the October 2015 issue of Scientific American. In the article, Stickgold, director of the Center for Sleep and Cognition at Beth Israel Deaconess Medical Center, in Boston, takes a close look at the latest studies on sleep’s role in mood, weight gain, immunity, and memory, including the finding that different types of memories are enhanced during REM versus non-REM sleep.
—Adapted from “Why we sleep,” by Christine Gorman, at http://scientificamerican.com/article/sleep-why-we-sleep-video.