Honeybees sleep several times during the day and at night. Up to now scientists were unsure of the reasons. Now it is clear that bees also use their sleep to improve their memories. In this experiment, the scientists conditioned the bees to a heat stimulus. During learning the bees were exposed to a fragrance that they linked to the learning experience. One group of bees was exposed to the same fragrance several times during deep sleep. This had a significant effect on memory: About 70 percent of the bees showed the learned behavior the next day when they were given a heat pulse. In the control group, only half of the insects exhibited this behavior.

"From experiments with mammals and humans, we know that such a trigger during deep sleep leads to brain activity," says Hanna Zwaka. "It appears that the brain of bees also repeats – triggered by the stimulus – what the animal learned and in this way enshrines what was learned in memory." By contrast, the Berlin biologists also demonstrated in experiments that this mechanism does not work in awake animals.