Why you need sleep
Posted on | July 30, 2009 | No Comments
So you can’t sleep. Will loading up on caffeine really help? Or is it better to plan a mid-day nap. Here’s what you need to know about sleep.
(Click here for 6 strategies for successful sleeping.)
Sleep nourishes us in different ways. For example, in REM (rapid eye movement) sleep, your brain processes information and comes up with creative ideas and problem solving strategies. Of the big three sleep stages–stage two, slow-wave, and REM—slow-wave sleep is the most restorative, says sleep researcher Sara Mednick, assistant professor at University of California, San Diego, and author of Take a Nap! Change Your Life (Workman, 2006).
Getting enough slow-wave increases natural growth hormone, which helps bone growth, muscles development, skin elasticity, and memory consolidation. Unfortunately, the length of time we spend in slow wave sleep decreases across our lifespan. “Even as early as age 40, there’s a correlation between age-dependent decreases in slow-wave sleep and some performance decreases across cognitive tests,” says Mednick. For example, we’re less able to process and remember basic information, but not necessarily skills. “Like if I tell you something once, it will be harder for you to remember it again,” she explains.
Getting enough slow-wave sleep is also important to help ward off obesity. That’s because this stage of sleep decreases cortisol, a stress hormone that serves a purpose but tends to linger unnecessarily, leading to increases in the kind of abdominal fat associated with heart attacks and strokes. Skimping on sleep, in general, disrupts a group of hormones called leptins and grehlins that tell you when you’re hungry and when to stop eating.
No matter what your age and what the cause, poor sleep can mess with your metabolism, says Helene A. Emsellem, MD, director of the Center for Sleep and Wake Disorders in Chevy Chase, Maryland, and author of Snooze… or Lose!: 10 “No-War” Ways to Improve Your Teen’s Sleep Habits (National Academies Press, 2006). Whether you have underlying sleep apnea (temporary, often repeated, cessation of breathing during sleep), chronic insomnia (inability to sleep or to remain asleep throughout the night), or just aren’t giving yourself enough time in bed, the tendency is to steadily gain weight and not be able to lose weight if you’re trying.
As for substituting caffeine for sleep when you’re tired, Mednick’s latest study shows it helps with alertness, but caffeine doesn’t clear the cobwebs out of your memory like a good afternoon siesta. “Everybody in the caffeine group showed decreases in performance compared to the nap and compared to placebo,” she says.
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