Have you ever wondered if insects sleep? As for someone who works with fruit flies, it seems like a no-brainer: yes, most animals sleep, and insects are no exception. But then again, have you ever seen a bee curled up under a blanket? Well, of course not.
So, to answer briefly: yes, insects do sleep, but not in the way you would picture it.
A sleep-like state
Sleep has been observed and described in many insects: bees, dragonflies, and flies. It has also been described in other arthropods, as well, such as scorpions, spiders, and crayfish.
In all fairness, researchers don’t usually call it “sleep.” They refer to it as a sleep-like state, a state of reduced mobility, and a lowered response to disturbances. Yes, you can poke a fly with a brush, and it will hardly react if it’s in this state.
Insects don’t tuck in like we do, but some clearly change posture while “asleep.” Many lower their antennae, crouch slightly, and fold their wings. They don’t curl up like dogs, and they don’t close their eyes, since they don’t have eyelids. And, importantly, not all insects sleep in the same way.
Some insects sleep during the day, some at night
We like to think of sleep as a nighttime activity. We are awake during the day and sleep at night. Most insects, however, are nocturnal or crepuscular, meaning they come out at night or at dawn.
Mosquitoes seem like they’re everywhere all the time, but you’ve probably noticed there are far more of them just after sunset, and no repellent seems to work.
Roaches, moths, and caddisflies also prefer the night shift. By contrast, bees, wasps, grasshoppers, and ants are mainly active during the day.
Sleep that looks a lot like ours
And then there are ants. They display something called micronaps—short bouts of sleep lasting up to 10 minutes, which add up to several hours of rest each day. Researchers have even observed rapid antenna movement during these naps, similar to our rapid eye movement (REM) sleep. For ants, though, it’s not REM but RAM: rapid antenna movement.
Not so different from human sleep, really. I’d bet they also dream, but we can’t know for sure. What we do know is that insect “sleep” has more in common with ours than you might think.
Insect sleep research helps us understand sleep
The fact that insect sleep is so similar to ours has pushed researchers to study it in detail to better understand human sleep. The field really took off after research in Drosophila showed that the same genes are turned on during both fly and human sleep. Yes, we share many of these genes with those pesky fruit flies.
The function of sleep is still one of science’s big mysteries. Interestingly, insect research, rather than human sleep studies, has provided key insights. Work in fruit flies revealed that sleep helps the brain reset its neuronal connections, which is essential for learning and adapting behavior. And yes, insects have brains, different than ours, but still comparable in many ways.
Bees also show striking parallels. After being forced to perform navigation tasks (thanks to scientists), they slept longer the next day, just like we do after an exhausting one. When deprived of sleep, they lost precision in their famous waggle dance and were less likely to return to the hive during navigation tasks.
How do you deprive a bee of sleep? By putting it in a centrifuge and giving it a few seconds of spin now and then throughout the night. Not very pretty, but it’s science.
The takeaway
Insects don’t curl up with pillows or close their eyes. We don’t know if they dream. But they absolutely enter a sleep-like state, so similar to ours that researchers can use it to study the function of sleep itself.
For insects and for us, sleep helps consolidate memories, reset the brain, and restore performance. Take it away, and both bees and humans get sloppy, cranky, and less effective.
So yes, insects do sleep. And they do it in a way close enough to ours that they’ve become an invaluable model for understanding why we need sleep at all.