Facing a whole hive of bees at once can be overwhelming—even for a bee. Young honeybees sleep more after spending time in the hive than after being by themselves. They need the extra nap time, it seems, to build and maintain their learning brains.
The first surprising thing about this might be that insects sleep at all. “Since around the 1980s there is good evidence that insects show…characteristics of sleep,” says Guy Bloch, who studies bee behavior at the Hebrew University of Jerusalem. Yes, their brains are tiny and organized differently from ours. But they rest in a similar way. And just as sleeping helps us sort through the new things we’ve learned each day, there’s evidence that sleep in bees and fruit flies is also tied up with memory and learning, Bloch says.
When a young worker honeybee emerges into the hive, she’s thrust into a social life with countless rules to learn. She finds herself surrounded by waving antennae, fuzzy bodies squeezing past each other, and a flurry of message-bearing chemicals. To find out how the bustle of hive life affects sleep, Bloch and his coauthor Ada Eban-Rothschild took some bees out of their colonies altogether.
The researchers looked at bees that had just emerged as adults. They let some of these bees spend their first one or two days in the colony; others were isolated in the lab. Then the scientists moved all the bees into individual cages for monitoring.
Bees that had been in a hive spent more time sleeping. And it wasn’t just an extra nap here or there. Immediately after leaving the hive, bees slept about five more hours per day. (In all, the socialized bees spent more than 60 percent of the day dozing.)
Something about colony life clearly conks out bees. To try to pin down that factor, the scientists put young bees back into their hives—but this time, they were in mesh cages that kept them separated from their sister bees. The young workers couldn’t touch antennae or rub bodies with the other hive members. This meant they were partially cut off from the colony’s communication. Surprisingly, though, these bees slept just as much afterward as bees that moved about freely.
Beehives are dark and densely populated, Bloch says, so bees probably don’t learn much by looking around. It’s not visual input that’s wearing them out. But pheromones or other smells may be part of the flood of information they experience. They may also learn from vibrations and sounds in the colony, or possibly even electrical signals, Bloch says.
Whatever information comes rushing at a bee during her first days in the hive, her brain clearly needs a lot of down time to process it. Next, Bloch wants to try and find out exactly what factors make these bees sleep more. Honeybees need to learn and remember a lot of things—flight paths to new food sources, dances to communicate their findings to each other—but Bloch wonders whether the social learning that happens inside hives might influence sleep even more than these tasks. It may be that no matter what species you are, navigating a buzzing social life is exhausting.
Image: by David Farquhar (via Flickr)
Eban-Rothschild A, & Bloch G (2014). The colony environment modulates sleep in honey bee workers. The Journal of experimental biology PMID: 25524987