Although little research exists on spider sleep, spiders are known to have circadian rhythms, or daily periods of activity and rest. Activity cycles vary by species. Certain spiders are mainly active at night; others take care of business during the day. Spiders hibernate in cold areas, allowing them to survive in a kind of suspended animation until it becomes warmer. While inactive, the spiders' metabolism slows.
Thousands of species of spiders exist around the world. Five thousand jumping spider species are known, and they make up only 13 percent of spider species, according to the University of Wisconsin at Milwaukee's Field Station extension website. Some set up camp in webs, but not all spiders create spider webs to trap prey. Trapdoor spiders create underground tunnels with hinged doors. Wolf spiders burrow and leap out at prey. The jumping spiders, of family Salticidae, also refrain from building webs, though they spin tether lines when they jump. Awake or asleep, spiders don't want to attract the attention of predators. They want to capture prey, eat, mate and create more spiders.
During hibernation, spiders tuck in their legs and their metabolic rates slow to help them survive. This means they don't burn as many calories and can survive without eating, living in a sleeplike state until cold weather ends. The same tucked-in position may indicate a sleeping spider. A spider lying on his back or in an awkward position with legs tucked is generally dead.
At least, as far as we know, spiders don't snore. Spiders are pretty savvy about taking care of their odds for survival, so they tend to hunt, nest and sleep out of harm's way. Contrary to urban myth, spiders don't commonly crawl into people's mouths while they're sleeping. They prefer to avoid humans. When spiders sleep or hibernate, they're most likely to be in their webs, in protected places such as cracks in walls or, among species that burrow, in tunnels.
Triggers besides circadian rhythms and cold temperatures can cause spiders to become unconscious. Researchers report that female funnel-web spiders (Agelenopsis aperta) lose consciousness during mating in response to males' pheromones. In an experiment to learn the effect of drugs on web-making, NASA discovered that chloral hydrate caused spiders to conk out instead of spinning their webs to completion. Other drugs, including caffeine and marijuana, caused some whacked spider webs.
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