Sleepy honeybees, much like sleepy people, struggle to recall experiences they have had just a day ago and to remember things they just learned. According to an article in Scientific American, neurobiologists at the Free University of Berlin have found that bees which have been deprived of sleep can't absorb and retain information as well as other bees. The scientists hope to use their findings to gain new insight as to how the brain uses sleep to organize and store information.

Study co-author Randolf Menzel told Scientific American, "We started with the idea that we could look for a neural substrate of learning and memory in bees, since they have a wonderful memory, can be easily trained, and we know their brain well at the neuronal level."

In the study, captive bees were taken to a new location and released about 600 meters from their home hive. Scientists observed how well they found their way home and how many bees got lost. That night, half of the bees were kept in a gently moving hive, which kept them from being able to rest and get a good night's sleep.  Bees typically take multiple small naps throughout the day and a longer sleep through the night.  Sleeping bees, say researchers, are easy to spot because their antennae droop.

When the two groups of bees were taken to a new location, scientists did not notice a difference between the rested bees and the under-slept bees in terms of how quickly they found their way home and how many of them got lost. From this, the team concluded that lack of sleep did not significantly impact the bees' ability to gain new knowledge.

However, when the bees were brought to the new spot for a second day, the bees who had slept both nights quickly remembered the path back to their hive and returned home. The bees who hadn't slept, however, took roughly the same amount of time to find their way home on the second day as on the first, meaning that they hadn't retained what they had learned from the day before, and attacked the problem as if they were facing it for the first time.

"This suggests that there are forms of learning that seem to be totally independent of sleep," Menzel said. But for the bees to learn the way home, store it and recall it for use later, sleep was necessary, or as SA said, "without sleep, the bees' brains could not properly consolidate memories from the night before.  If they are correct, the finding adds to growing evidence from a number of human and animal studies that sleep plays an important role in memory and learning."

The University of California at Los Angeles's Jerome Siegel believes that the study needs to find a way to distinguish between memory and task performance.  "We all do tasks more poorly, especially recently learned tasks, after sleep deprivation but may be able to perform them properly after getting sleep at a subsequent time. In other words, consolidated memories may not be accessed in sleepy animals," he said.

However, neuroendocrinologist Jan Born at Germany's University of Lübeck believes that the results show great promise for future understanding of sleep and its role in memory.  "I think this is a very valuable finding for the whole field—it shows the formation of memories is hampered when bees do not sleep or rest," he said.

The Free University of Berlin study was published on October 25 in the Journal of Experimental Biology.

[image of a honeybee on an echinacea flower via Shutterstock]