Every other Friday on Morning Edition, Outside/In host Sam Evans-Brown tackles a question from a listener. This week, we're buzzing, because...
...Carolyn from Maine asks: “This summer there’s been a lot of attention paid to diseases like EEE, which can be transmitted from a bite from an infected mosquito. But my question is, during the middle of the day when these species of mosquito are less likely to be feeding, what are they doing instead? Which made me wonder if mosquitoes sleep?”
My wife and I have a long-standing debate in which she insists that mosquitoes go to bed, and I insist that mosquitoes are like tireless, blood-sucking robots that are up at all hours lusting after our bodily proteins.
Fortunately for our question asker, and for my wife and I, the mosquito is perhaps the most studied insect in the world, due to the fact that it is the creature that causes the most human mortality in the world–more than dogs or bees or sharks or hippos—mosquitoes are our apex predator.
And according to Laura Duvall, who leads a mosquito lab at Columbia University, you do see behavior in mosquitoes that looks a lot like sleep. They land and they hang out for long periods of time … but is that actually sleep?
And much to my dismay, Laura says for a few reasons they think it is.
She explains that, “if you sleep-deprive them—if you don’t let them sleep when they would normally sleep, they recover it later,” just like teenagers staying up until 3 a.m. watching YouTube videos.
The other bit of research that convinces us this is sleep and not just resting comes from fruit flies (and actually resulted in a Nobel Prize) but Laura says it is generally believed to be true of mosquitoes as well.
“If you feed caffeine to fruit flies they actually sleep less,” she says, “So the same types of drugs that can change human sleep also affect their sleep, and if you give them sleeping pills you’ll see more sleep!”
And that’s not all!
“Just like humans get jet lag, when they move across time zones, mosquitoes too can get jet lag,” says Anandasankar Ray, another mosquito researcher at University of California Riverside.
So while we have not peered into the tiny mosquito brain to see if they are dreaming, everything about this looks a lot like sleep.
The Aedes mosquitoes–those are the ones that carry Zika, eastern equine encephalitis, and chikungunya—they sleep at night, and take a siesta in the middle of the day. The Culex mosquitoes, which carry West Nile Virus, they’re active at night.
But much to my dismay with regards to my assertion that mosquitoes are indefatigable robots, sleep is in fact fundamental to life.
“We see sleep in animals ranging from microcopic nematode worms, to fish, to insects, to mammals and, of course, to humans.”
Now, why do all of these living things sleep? That’s a question we still don’t have an answer to.