Spiders are fascinating creatures that inhabit almost every terrestrial environment on earth. Many people wonder if these eight-legged arachnids get any shuteye when the sun goes down or if they stay up all night long spinning webs and catching insects. In this article, we’ll explore what science tells us about spiders’ sleep habits and circadian rhythms.
Do Spiders Sleep?
Yes, spiders do sleep! They exhibit periods of inactivity and reduced responsiveness that meet the basic criteria for sleep. However, their sleep is quite different from human sleep or even the sleep patterns of mammals and birds.
Like all animals, spiders need time to rest and recover metabolic functions. But as invertebrates, their sleep is not associated with the same brain wave patterns as vertebrate REM and non-REM sleep cycles. Their sleep is characterized by stretching out their legs, ceasing movement, and reduced responsiveness to stimuli.
Spider Circadian Rhythms
Most spiders exhibit circadian rhythms, meaning they have internal biological clocks that regulate cycles of activity and inactivity over a 24-hour period. This corresponds with day/night cycles.
Studies have shown that many spider species, like the common house spider, are more active at night and sleep more during the day. Their peak foraging time is during dusk and dawn. This pattern likely evolved to take advantage of insect prey that is also more active at night.
How Long Do Spiders Sleep?
Research suggests that different spider species sleep or exhibit inactive behavior for varying lengths of time over a 24-hour period. Some key findings on spider sleep duration include:
- Jumping spiders sleep around 10 hours per day, with their longest sleep bout around dawn.
- Wolf spiders sleep 7-10 hours per day and are mostly active at night.
- Cellar spiders may sleep up to 16 hours per day, with much of this inactivity concentrated during daylight hours.
- Tarantulas sleep around 8 hours per day on average, with their peak active period at dusk to midnight.
So spider sleep durations are roughly similar to human sleep patterns, albeit distributed differently throughout night and day. Like humans, younger juvenile spiders tend to sleep more than mature adults.
How Do Spiders Sleep?
When sleeping, spiders assume a curled-up posture by bending their legs in toward their bodies. They remain motionless in this sleep posture for extended periods of time.
Spiders don’t have eyelids to close while sleeping. But observations show they do move their front legs over their eyes as they settle into sleep. This likely blocks out light.
Different spiders exhibit some unique sleeping postures based on their anatomy and habitat:
- Jumping spiders draw their legs in close to their bodies like a tight ball.
- Suspended web spiders curl up tightly in the corners or centers of their webs.
- Burrowing spiders remain dormant in underground silk-lined chambers or tubes.
- Aquatic spiders curl up under rocks or plants in shallow freshwater habitats.
Interestingly, male spiders have been observed assumed a special posture while sleeping near females to avoid being mistaken for prey!
Do Spiders Sleep in Webs?
Web-building spiders like orb weavers do take rest within their intricate snare webs. The webs provide protection while the spider remains in a suspended curled posture. An individual spider may return to the same general area of the web to sleep after it has capturing prey there at night.
Web spiders invest significant energy resources into spinning their large webs. So remaining within the web to rest after construction makes evolutionary sense. The web likely provides a signal to the spider’s nervous system indicating a safe space for sleep.
However, spiders don’t actually sleep “in” their webs by attaching their legs directly to the silk strands. Instead they will rest in a tucked posture at the web’s center or periphery. Some orb weavers spin specialized silk sleeping sacs or retreats within one section of the larger web.
Do Male and Female Spiders Sleep Differently?
Researchers have documented some variations in sleep patterns and behavior between male and female spiders of certain species. Some key gender differences include:
- Male spiders may sleep longer – In the orb weaver Larinioides cornutus, males slept over 13 hours while females slept around 11 hours per day.
- Male spiders modify sleep postures near females – Male Pholcus phalangioides curl only back legs inward around females to avoid being seen as prey.
- Female spiders may briefly disrupt their sleep to care for eggs – Female wolf spiders interrupt sleep to turn egg sacs, improving oxygen circulation.
In some species, these gender differences in sleep habits may relate to the effort required for courtship, mate-seeking, web-building, or childcare.
Do Baby Spiders Sleep?
Baby spiders, known as spiderlings, do indeed sleep! Spiderlings hatch from eggs and are essentially miniature versions of adults. Like other juvenile animals, they spend more time asleep as newborns compared to adult spiders.
For example, a study of newborn jumping spiders showed they slept around 14 hours per day, while adult jumping spiders slept around 10 hours. Baby spiders need extra sleep as critical nervous system development occurs during infancy.
Interestingly, social spiders like Stegodyphus lineatus exhibit cooperative baby care. Adult females share overnight childcare duties like web maintenance. This allows each spider to get necessary sleep while also caring for offspring.
Unusual Spider Sleeping Habits
While most spiders follow expected nighttime sleep and daytime activity patterns, some exhibit unusual sleep-related behaviors:
- Redback spiders: Female redback spiders attract mates by sleeping near the edge of their webs and releasing pheromones.
- Tarantulas: Some tarantulas have evolved the ability to essentially switch off their leg muscles allowing legs to go limp when sleeping in branches.
- Cyclosa spiders: These orb weavers build decoy spider models out of prey remains, shells, and debris within their web to confuse predators while the spider itself rests.
There is still much to learn about spider sleep and why different species evolved such unique resting behaviors!
Do Spiders Dream While Sleeping?
This is a fascinating question still being explored by spider sleep researchers! Most experts believe it is unlikely that spiders experience complex symbolic dreaming like humans given differences in neurology and brain structure.
However, some think basic spiders may still undergo simple imagery processing related to visual stimuli and memory consolidation. There is evidence from other invertebrates like flies and bees of replaying visual information during rest states.
Understanding dreaming in spiders will require more comparative work linking neural activity to sleep-like states across different species. But for now,imagining what a jumping spider might dream about remains firmly in the realm of speculation!
Why Do Spiders Need Sleep?
Like other animals, spiders require sleep primarily for:
- Energy conservation – Sleep reduces energy use and metabolic rate, allowing spiders to function with limited food intake.
- Neural recovery – Sleep allows repair and reorganization of connections in a spider’s neural networks.
- Cognitive performance – Rest improves learning, memory consolidation, and responsiveness when awake and hunting.
Going without adequate sleep severely impacts spiders’ basic functions. For example, studies of wolf spider sleep deprivation show negative effects on feeding, web construction, and even immunity to pathogens.
Sleep offers spiders the same recuperative benefits it provides more complex animals. It is an essential behavior for efficient functioning of their small nervous systems.
Do Spiders Ever Lack Sleep?
In the wild, spiders likely do not experience chronic lack of sleep or disruption in their natural sleep cycles. Their circadian biology drives innate sleep/wake patterns even without environmental cues.
However, spiders in laboratories may suffer impaired sleep due to unnatural lighting, exposure to chemicals, or constant handling by researchers. Effects of inadequate sleep seen in lab spiders include:
- Decreased responsive to stimuli
- Reduced appetite and weight loss
- Increased mortality rates
Stressors like extreme weather and difficult conditions in nature could also conceivably disrupt a spider’s sleep in its natural habitat.
Overall though, spiders seem capable of maintaining healthy sleep regulation even in changing environments. After millions of years evolving alongside daylight/darkness cycles, their circadian clocks are deeply engrained.
Final Thoughts
Spiders exhibit sleep states remarkably similar to other animals, though adapted to their unique physiology and environmental pressures. Clearly sleep is fundamental for spiders, serving vital biological functions. There is still much more researchers are working to uncover about differences in spider sleep across species and sexes.
While humans gaze up at night and wonder if spiders lying in wait in shadowy corners ever take time to rest, science assures us these creatures have their own nightly rituals of repose. All living things require sleep’s restorative embrace.
