Frigatebird. Credit: Max Planck Institute.

Endurance is a hard-won characteristic of many elite athletes and is vital to winning most sporting competitions. If great frigatebirds could compete this summer, they would certainly take home a medal for endurance flight.

Frigatebirds are large sea birds with wingspans of more than six feet across. They are really good at gliding and can fly nonstop for weeks at a time. Researchers who study these birds suspected the birds got some shut-eye during these flights.

Recently,  Max Planck Institute for Ornithology researchers examined whether these birds are able to take naps while flying—yes, you read that right, while flying. To examine this, the team attached flight data recorders and measured brain activity of birds in flight.

The birds were awake and actively foraging during the day. However, at night the brain activity of the birds switched to a pattern that suggested they were taking short naps that were up to several minutes long while continuing to soar through the skies. In addition, they discovered that each hemisphere of their brain could take turns sleeping (i.e., unihemispheric sleep) or both sleep at the same time (i.e., bihemispheric sleep). Unihemispheric sleep allows the birds to stay partially alert to potential dangers,  watch where they are going and, of course, prevent themselves from falling from the sky.

This made me wonder how they prevent a crash landing when both sides of their brains take a nap. As it turns out, sleep duration for this deeper form of REM sleep only lasted a mere seconds and did not affect their flight pattern. Remarkably, these birds only average 42 minutes of sleep per day while out at sea. Researchers are still trying to figure out how they are able to function on such little sleep when they are known to sleep for more than 12 hours on land.

My thought is there must be a Starbucks in the sky.

Karen Sweazea, PhD, is an associate professor in the School of Nutrition & Health Promotion and the School of Life Sciences at Arizona State University.