Do Insects Sleep

Sleep restores and rejuvenates. Without it, our minds arent as sharp, and our reflexes become dull. Scientists know for sure that birds, reptiles, and other mammals experience brain wave patterns similar to our own during periods of rest. But what about insects? Do bugs sleep? Its not quite as easy for us to tell whether insects sleep the way we do. They dont have eyelids, for one thing, so youll never see a bug close its eyes for a quick nap. Scientists havent found a way to study insect brain activity, as they have in other animals, to see if typical rest patterns occur.   Studies of Bugs and Sleep Scientists have studied insects in what appears to be a resting state, and have found some interesting parallels between human sleep and insect rest. In a study of fruit flies (Drosophila melanogaster), researchers videotaped and observed individual fruit flies in order to determine whether they slept. The study authors reported that the insects exhibited behaviors that suggested a sleep-like state. At a particular time in the circadian day, the fruit flies would retreat to their preferred napping locations and get comfortable. The insects would remain still for over 2.5 hours, although the scientists noted the flies would sometimes twitch their legs or probosces while at rest. During this period of rest, the fruit flies didnt respond easily to sensory stimuli. In other words, once the fruit flies were snoozing, the researchers had a tough time waking them up. Another study found that usually diurnal fruit flies with a certain gene mutation would become active at night, due to increased dopamine signals. The researchers noted this change in nocturnal behavior in fruit flies is similar to that seen in humans with dementia. In dementia patients, an increase in dopamine can cause agitated behavior in the evening, a symptom known as sundowning.   Studies have also shown that insects deprived of rest suffer much like people do. Fruit flies kept awake beyond their normal active period would recover the lost sleep by napping longer than usual when finally allowed to rest. And in one study population that was denied sleep for an extended period of time, the results were dramatic: About one-third of the fruit flies died. In a study of sleep-deprived honey bees, the insomniac bees could no longer perform an effective waggle dance to communicate with their colony mates. How Bugs Sleep So, by most accounts, the answer is yes, insects do sleep. Insects clearly rest at times and are aroused only by strong stimuli: the heat of day, the darkness of night, or perhaps a sudden attack by a predator. This state of deep rest is called torpor and is the closest behavior to true sleep that bugs exhibit. Migrating monarchs fly by day, and gather for large butterfly slumber parties as night falls. These sleep aggregations keep individual butterflies safe from predators while resting from the long days travels. Some bees have peculiar sleep habits. Certain members of the family Apidae will spend the night suspended by only the grip of their jaws on a favorite plant. Torpor also helps some insects adapt to life-threatening environmental conditions. The New Zealand weta lives at high elevations where nighttime temperatures get quite icy. To combat the cold, the weta simply goes to sleep at night and literally freezes. In the morning, it thaws out and resumes its activity. Many other insects seem to take a quick nap when threatened–think of the pillbugs that roll themselves into balls the moment you touch them. Sources: Do Insects Sleep or Are They Just Feigning It?, Tom Turpin, Professor of Entomology, Purdue UniversityDo insects sleep? The Straight Dope MailbagHendricks et al. Rest in  Drosophila  Is a Sleep-like State, Neuron  25(1), January 2000, pp.129–138.Shaw et al. Correlates of Sleep and Waking in  Drosophila melanogaster,  Science  287(5459),10 Mar 2000  pp.1834-1837.Genetics and Molecular Biology of Rhythms in Drosophila and Other Insects, by Jeffrey C. Hall, 2003.The Mystery of Sleep: Keeping Flies on the Clock, Penn Medicine, University of Pennsylvania. Accessed online March 2, 2016.Sundown Syndrome-like Symptoms in Fruit Flies May be Due to High Dopamine Levels,  Penn Medicine, University of Pennsylvania. Accessed online March 2, 2016.Klein et al.  Sleep deprivation impairs precision of waggle dance signaling in honey bees,  Proceedings of the National Academy of the Sciences of the United States of America 107(52), 28  December 2010.