Researchers have explored the deep-sleep state of honeybees, using an odor associated with a training task to enhance the sleeping insects’ memories of what they had learned. When tested upon waking, the bees’ recall was boosted in comparison to bees who did not receive that odor prompt. The same phenomenon is seen in similar experiments with humans, leading the researchers to conclude that deep sleep for bees is, as it is for us, a time for processing memories.
“In deep sleep, their muscles are fully relaxed and their antennae and body sink to the ground,” says Hanna Zwaka, a neurobiologist at the Leibniz Institute for Neurobiology in Germany, who led the study of sleeping honeybees. “What does that have to do with dreaming? We believe that some of our dreaming could reflect similar reactivations.”
Less is known about the active sleep state in bees, but one theory holds that REM sleep—its dream-saturated mammalian analogue—occurs while a brain optimizes its models of the world. Rather than reviewing a day’s memories, the REM-sleeping brain runs simulations reassembled from previous experiences, preparing itself to better navigate an unpredictable world upon waking. Active sleep has not been studied in bees, but it has been documented in fruit flies.
“The brain looks like it’s still awake, but the fly is unresponsive to the outside world,” says Bruno van Swinderen, a neurobiologist at the University of Queensland in Australia who has studied sleep and cognition in flies. “They’re in some kind of altered state that is basically similar to what we think is happening in REM sleep.” The same likely occurs in bees, he says.
And what might a bumblebee dream of? The moments of their life, perhaps: the flowers they have visited, their taste and smell. The paths they followed to get there. Other bees they have known. Zwaka thinks bees “might dream about anything they have learned—colors, odors, or places.” Perhaps, says Zwaka, my bumblebees atop their asters dream of their warm home.
I wonder whether, much as our own dreams may incorporate some stimulus from the external world—a song drifting through an open window, mysteriously woven into the dreamtime narrative—so might the same happen to a bee. The warm aster blossom embrace, the full stomach, every sense pervaded by the flowers that are so central to their existence: How could a dream in such conditions be anything but beautiful?
Late in autumn, when only a few asters remain in flower and the days feel suddenly short, I walk by them each evening and morning, looking for bees and hoping for just one more day before the hard frost that will bring their final sleep. Of course, the days will run out; rather than being revived by the sun, they will fall from the flowers. Foreknowledge and its sadness are inescapable. But at least there is this small peace, this kind departure for the bumblebees whose efforts have helped the world bloom.
Not many animals die so well. Most will die of disease, injury, starvation, or predation. And as much as we want to believe that humans have exempted ourselves from this cruel fact of life, our own deaths are frequently protracted and painful. To see an aster, though, is to know that at least someone is departing with grace. To tend asters is a gesture of hope, a small and profound act of benevolence.
It is early spring now. Last year’s asters are still brown and dormant. Bumblebee queens are dormant too, nestled in the burrows from which they will emerge in tandem with spring’s first flowers. The blossoms and their bees are a memory and an anticipation, but the days are getting longer. Soon it will be time for planting.
This story originally appeared in Nautilus