Do bees sleep?
In 1983, a team from the Department of Zoology and the IUT (Technische Hochschule) of the University of Darmstadt, around Stefan Sauer, Eva Hermann and Walter Kaiser, subjected foraging bees to a sleep deprivation experiment. They observed that they communicated less well (they performed poorly the dance which is used to indicate to the congeners where there is a source of food that they discovered), and that they lost their sense of direction (they had struggling to find the hive after an excursion outside, or even get lost forever).
Their experience has shown that if you keep foragers all night in a fully waking state, they will literally "fall" into the equivalent of real, deep sleep. Sleep plays an important role in the ability to learn and remember, and it is necessary for the transfer of short-term memory to long-term memory.
The sleep phase is characterized in the bee by an inclination of the head and a muscular relaxation as well as a folding of the antennae against the head. It remains motionless and clings to the spokes with the head positioned at the top. The heartbeat slows down and in the deep sleep phase his breathing is very reduced. If her sleep is suddenly interrupted she catches up during the next break, which then lasts much longer.
The annual activity of bees follows the rhythm of the sun, with a cluster that grows until the summer solstice and then decreases until that of winter. This annual rhythm corresponds to a daily rhythm: the bees are active during the day and stop at night. They reform the bunch to keep warmer. However, they do not “sleep”, because they have urgent tasks to accomplish: the care to be given to the brood does not stop overnight, the frames to be built urgently during intense honey flow will also be done during the night.
More generally all the young bees, the internal bees of the hive (nurses, cleaners, waxers and builders, storekeepers) work during the night as soon as an urgent task requires them.
It is unknown if the bees are dreaming. Although unlike mammals they probably do not have REM sleep phases, this does not exclude the possibility of punctual dreams where they would smell or see the color of flowers.