An airliner cruising at 30,000 feet doesn’t seem the most likely place to consider the value of play, but Delta Air Lines passengers who bothered to browse the July edition of the airline’s in-flight magazine got a small crash course in the value of letting loose.

Sky magazine writer Mark Anderson reported on recent research supporting the benefits of simple play in boosting creativity as well as productivity at work. Laboratory rats that were allowed to play were better able to respond to stress and solve problems than rats that were denied those opportunities.

In other words, too much of the world’s rat race is bad for rats — and, by implication, for humans, too.

Anderson tells readers that beneficial play for people can be structured games, but doesn’t have to be. “The answer might be in sports or taking up an instrument or joining a book club or writers’ group,” he writes. “Maybe it’s as simple as trying out new recipes at dinner or building that model airplane you never got to make as a kid.”

Anderson’s advice is worth noting here in summer, when fun is supposed to be near the top of the agenda, and it’s also worth keeping in mind throughout the year.