Friday, November 15, 2013

Science Friday: A Good Night's Sleep

Exercise helps you sleep—that's not particularly shocking. And most runners aren't surprised to hear of its role in stress relief. So it stands to reason that when you're so stressed out that you're tossing and turning at night, going for a run could provide a double benefit: less stress and more sleep.

Monika Fleshner's group presented data at the Society for Neuroscience Conference in San Diego (a great place for a run
—stressed or not) that investigated, in a number of ways, the relationship between exercise, sleep, and stress. One study, led by Robert Thompson, a PhD student at University of Colorado-Boulder, asked if exercise could help stressed rats sleep better. Half of the rats were able to run on a wheel, while the other half remained sedentary. (The rats weren’t forced to run, but were given access to running wheels in their cages and could run as they pleased. Rats voluntarily run about 5K each night.) After six weeks, the rats were stressed with shocks to their tails. Their sleep/wake cycles were studied both before and after the stress.

Before stress, exercised rats spent more of their time in REM sleep—the stage of sleep when dreams occur—compared to non-exercising rats. Directly after the stress, all the rats had a rough time sleeping—they got the same amount of REM sleep whether it was day or night. But by the very next day, the running rats were able to recover their sleeping habits. The sedentary rats struggled for a few more days.

But rats are rats, what about people?

Most of the studies on people (described here, here, and here) don't look at stress, but agree that running helps sleep in general. In contrast to rats, however, exercise decreases REM sleep in humans, while increasing non-REM sleep (including deep sleep). When looking at people who have trouble sleeping, like insomniacs, exercise takes longer to have an effect. But the moral of the story is the same: exercise will eventually help you sleep, no matter how stressed.

Another interesting story from the Society for Neuroscience conference: When asked if mental games (like crosswords) or exercise is better for brain health, scientists agreed that the jocks win. So put your crossword down and go for a run! If nothing else, maybe you’ll get a better night's sleep instead of tossing and turning over the answer to 7 Down.

Dream big and sleep well,