Many humans work 8 hours a day, 5 days a week, some 261 days in a year. We run a tight schedule and for much of our adult life, we do a lot of work. But that’s nothing compared to bees.
Bees are some of the hardest-working creatures in the world. In a single day, a bee can visit more than 1,000 flowers to extract nectar and pollen, which it then brings back to the hive. For solitary bees, the work doesn’t even end there, as female bees need to defend their own nest, lay eggs, and feed the offspring without any help. In social and colony-forming bees, division of labor is prominent and each individual takes on a role (like defender or worker) specializing in one task.
With all this work, one can’t help but wonder: do bees even have the time to sleep?
To Sleep Like a Bee
Back in 1916, two researchers challenged the biological community to look further into the question of insect sleep. Like children, the two researchers argued, scientists only focus on insects when they are active, and don’t really pay much attention to the sleep part.
“An object in motion always attracts the attention of children, young and old; a butterfly flitting from blossom to blossom, a locust jumping before one in the dusty road, a bee rummaging in a flower, all arouse one’s interest. But naturalists, like children, cease to pay attention to insects when the latter cease their activity. Thus the interesting problem of when, where and how insects sleep has been all but neglected,” the 1916 study abstract reads.
Fast forward over a hundred years, and we know quite a bit more about insect sleep — but not everything.
The first problem is figuring out when exactly bees are sleeping. Bees don’t have eyelids so you can’t just look for a bee with its eyes closed. Perhaps this is why scientific studies on bees’ sleeping behavior were not conducted until the 1980s. But the first clues came from the antennas. By carefully following bees, scientists figured out that honeybees sometimes stay still and stop moving their antennae. They also tuck their head and tail in and rest their wings. Sometimes, bees can sleep so deeply that they can even fall over sideways.
Research shows that bees tend to sleep five to eight hours, generally at night. Generally, young bees tend to sleep much more than older bees, which sometimes only sleep 30-90 minutes a day, in small catnaps of 15-30 seconds.
Researchers note a series of physical changes that take place when bees are sleeping. In addition to being immobile, bees also cool down when sleeping, and their body temperature can go down quite significantly (much like in humans). Also, the deeper a bee sleeps, the harder it is to wake it up (again, much like in humans). Bees also seem to be aware when their hive mates are sleeping. When a bee is sleeping deeply, others will hang onto its leg so it won’t fall off the honeycomb.
Sleep is integral to the bees’ health, researchers have found. Their brain exhibits specific patterns when sleeping, and while the effect of sleeping on the bee brain isn’t well understood, it seems likely that it plays a key role in various cognitive aspects. Tired bees tend to sleep more, and sleep-deprived bees function significantly worse in key aspects.
But it’s important to keep in mind that not all bees are the same. There are over 20,000 known bee species in the world, and 75% of them don’t even live in hives — they’re solitary. Another 15% of bees are brood parasites, which leaves just around 10% of bees that are social. Since the lifestyles of these different types of species are not the same, their sleeping patterns are also different.
Honeybees tend to move around more when their sleep and their antennas are more unsteady than in solitary bees. This could be because the lifestyles of social bees are more complex and include social cues, which could leave the brain still processing information into the night. Meanwhile, for solitary bees, conserving energy is the primary objective.
Where bees sleep
In order to get a good night’s sleep, bees need to be careful in choosing the location where to rest. Yet again, there are differences based on age and on the type of bee species.
Female solitary bees usually sleep in their nests alongside their offspring — but this is not the case for males. The male bee finds solitude in flowers and grass stalks. They clamp on to the end of a twig for increased protection. This serves as camouflage as they blend in with the plant, which can confuse predators, and this portion is also less accessible to intruders like ants.
Honey bees, on the other hand, do not have the luxury of choosing their sleeping den as it is predetermined by their role in the colony. Their hive is generally divided into different sections where the older or forager bees sleep toward the perimeter, and the younger ones sleep inside cells that are closer to the center of the nest. The queen bee, the only female that has fully developed ovaries, stays in the center to ensure that she is safe. Sometimes, a worker bee may be surprised by nightfall or dropping temperature and may sleep outside, returning with the pollen in the morning.
Forager social bees (generally the older workers in the colony) have a fixed sleep schedule. They are active throughout the day and sleep at night in the hive. Foragers have different stages of sleep (lighter and deeper), and when they awake, they can spend a bit of time getting ready or grooming themselves. Meanwhile, the youngest worker bees, whose main duties include cleaning the hive cells, have no fixed sleeping patterns and may take naps at various times during the day.
Our bees lack sleep — and it’s a problem
Bees (and pollinators in general) are essential not just for the well-being of ecosystems, but also for human activity. These insect pollinators contribute to our economy much more than previously estimated. Bees generally play an important role in agriculture by pollinating farmers’ crops and providing us with food. Researchers from the University of Pittsburgh and Penn State University quantified that the economic value of bees totaled $34 billion in 2012 — and the figure has only grown since then as agricultural practices have intensified.
But despite all the help they’re giving us, our activity threatens bees in a number of ways, including disturbing their sleep.
A study from researchers at the University of Bristol revealed that, currently, our bees are experiencing alarming levels of sleep deprivation and we humans are to blame. Their lack of sleep is caused by the pesticides we use. Chemicals used in commercial pesticides were found to disrupt the body clock of bees resulting in them foraging less and sleeping more during day time, which has cascading effects on the bees health. Dr. Kiah Tasman, the lead author of the study, explained that if bees go out more during the night, it will greatly reduce their chances of collecting food as flowers are not available during this time. This will surely affect their colony’s health as nectar and pollen are vital for growth and reproduction. Another 2020 study found that sleep in honey bees is affected by the herbicide glyphosate.
Sleep-deprived honey bees, Apis mellifera, were also reported to have decreased precision in performing the waggle dance, a well-known communication strategy in bees. The waggle dance is performed by a successful forager inside the hive. Through a series of movements, the bee precisely signals information on the direction and location of abundant and good quality food sources.
With almost 90% of wild plants and 75% of global crops depending on bees, the decreased efficacy of their pollination will certainly have disastrous ecological and economical effects. Though minute is size, the magnitude of their contribution is what sustains 7 billion people on this planet. If we do not want our markets and plates to be empty, then we should work harder to prevent a world without bees.