I haven’t used an alarm clock in more than 30 years. I go to bed when I’m tired and get up when I awaken. I trust my body to tell me when it’s had enough rest, and I pride myself on “only” needing five or six hours most nights. Manly men don’t sleep their lives away.
Trusting my body seems wise and reasonable enough. Except for one thing: my body has a lot of miles on it, and I’m overweight and out of shape – not the best body to trust! Especially with something as critical to good mental and physical health as sleep. How critical is sleep? More essential than many sleep researchers ever imagined until recently. Here are two studies for starters: This first one suggests that when we lose sleep we lose brain tissue, gray matter in the cingulate gyrus and the hippocampus, essential areas long known to be stress sensitive. The less sleep we get, the worse we tend to handle stress. The more difficulty we have handling stress, the worse the decisions – big and small – we make in our day-to-day lives.
This second study, by Dr. Avi Sadeh at Tel Aviv University, seems to indicate that when kids chronically lose an hour of sleep, they lose the equivalent of two years worth of cognitive maturation and development. Two years! That’s huge. How many kids end up being kept back in school or do poorly on standardized tests simply because they’re not getting enough sleep?
Kids, it turns out, are exponentially more vulnerable to sleep loss than adults. Why might that be? Well, one reason is that the emotional content of a memory affects where it gets processed in the brain. Negative emotions get processed by the amygdala. Positive or neutral memories get processed by the hippocampus. When kids (and adults) lose sleep, it affects the hippocampus much more than it does the amygdala. The result: kids who are sleep-deprived end up storing and recalling many more negative memories than they do positive ones. It’s not too great a leap to guess that this sets the stage for significant depression down the road.
Taking sleep research to heart, a number of school districts around the country have decided to start school an hour later. Edina, Minnesota is one such district. In response to the later start, kids there raised their math SAT scores 56 points and their verbal scores 156 points! A combined 200+ points just by getting more sleep! They also reported greater motivation and less depression. Another school district in Lexington, Kentucky also decided to experiment with starting school later. The result: teen auto accidents in Lexington were reduced by 25% compared to other Kentucky districts.
Here’s the clincher, however: reduced sleep appears to be contributing directly and indirectly to the obesity epidemic in America’s children. Indirectly, if kids are retaining and recalling more negative memories, eating is one way to make yourself feel better. For the direct effect, we can look at the work of Eve Van Cauter. What she discovered is that sleep loss increases ghrelin production and reduces leptin production. Ghrelin increases hunger; leptin suppresses it. She also discovered that sleep loss elevates cortisol levels. Cortisol stimulates the body to make fat. Sleep loss also disrupts human growth hormone production, which is essential for helping the body process fat. This connection between sleep loss and weight gain is something few obesity researchers factor into, or control for in most research.
Napping for the Benefit of the World
As a kid in the early grades, we were required to take naps. I used to think that it was solely to preserve the teacher’s sanity. But new research suggests that additionally it might have been for our well-being. It turns out that only six minutes of deep sleep in the middle of the day improves declarative memory performance. It may contribute to many other aspects of well-being as well that we haven’t tested yet, such as improved impulse control and increased immune function, in fact, anything attributed to pre-frontal executive functioning, I would hypothesize improves with regular napping. It’s sort of like a mid-day pit-stop to consolidate learning and off-load data from our working memory circuits into long-term storage.
I hope you found this new research as eye-opening as I did. And now it’s time for me to sign off and get a little mid-morning shut-eye.