The average house cat sleeps an awful lot, though not as much as you might think: 12 hours a day, on average. Dogs tend to sleep 10 hours a day. Squirrels seem pretty active, but actually sleep about 15 hours a day. Your pet gerbil clocks in at 13 hours a day, on average. That cow grazing in the field? Only 4 hours a day. That brown bat hanging in the tree? A full 20 hours a day.
These are all fun facts, but is animal sleep scientifically meaningful in relationship to human sleep? Some researchers believe sleep is a cross-species “universal function,” meaning that its purpose began early in animal evolution and so studying the sleep of animals can help us understand human sleep. Other researchers caution that animal sleep is an example of “convergent evolution,” meaning that different species evolved to exhibit similar functions that serve different purposes.
Which bring us to #insects. Yes, insects sleep. In fact, researchers probing the mysteries of human sleep pay special interest to drosophila melanogaster, or the common fruit fly. Why? Because the fruit fly’s genome has been completely mapped, it reproduces easily in captivity, and has sleep habits that on the surface are similar to those of human beings.
Dr. Joan Hendricks of the University of Pennsylvania published the first study of fruit flies in 2000, demonstrating that the creatures exhibited a “rest state”—in other words, they slept. In the years since, researchers at a number of institutions have extended this work.
Dr. Amita Sehgal and her colleagues, also at the University of Pennsylvania, published a study on sleep deprivation based on fruit flies. The study demonstrated that sleep deprivation at early stages of life can have repercussions later in the life cycle. Dr. Chiara Cirelli and her colleagues at the University of Wisconsin—Madison have studied the fruit fly to attempt to confirm the idea that human sleep serves an important function in regulating brain plasticity, or the ability of the brain to change, grow, and remap itself over the course of time.
As another researcher, Dr. Dragana Rogulva of the Harvard Medical School says, “I believe that by studying the fly we can find factors that specifically regulate how we fall asleep, how we stay asleep, and how we wake up.” Dr. Rogulva has been studying insomnia in fruit flies with the hopes of laying the groundwork for the development of more effective sleep medications.
While animals may be best for cute gifs and cuddly listicles, fruit flies may provide a conduit to a deeper understanding of sleep.