Hermit crabs are nocturnal animals that sleep for 6 to 8 hours during daylight hours. However, they may sleep longer during the summer to avoid light and heat.
Multiple hermit crabs in a single enclosure will pile on top of each other.
Most hermit crabs burrow themselves under the substrate to sleep, which is a holdover from the wild. In nature, hermit crabs hide under the sand to avoid the sun’s rays and predators.
Some hermit crabs prefer to sleep by hanging from the roof of an enclosure. This is a natural behavior, but ensure your hermit crabs have enough substrate in case they lose grip and fall.
Hermit crabs won’t leave their shell while sleeping and shouldn’t be active during daylight. If this is the case, they may be too hot, lack space, struggle to breathe, or find their terrain too noisy.
When Do Hermit Crabs Sleep?
According to the Brazilian Journal of Biology, wild hermit crabs are nocturnal.
Common predators, most notably birds, will be active during the sunlit hours. As hermit crabs are native to warm terrain, they can also overheat in the sun.
Hermit crabs will sleep away the day and start to emerge after dark. Most hermit crabs will wake up at dusk or just after, becoming active for the night, then head to sleep at daybreak.
Can I Reverse a Hermit Crab’s Sleep Cycle?
You can theoretically reverse the sleep cycle of hermit crabs, making them diurnal rather than nocturnal, but it’s not recommended.
If you plan to change a hermit crab’s sleep routine, reverse the lighting in a habitat. Keep a room dim during the day, as bright lights upset hermit crabs, and apply more illumination at night to encourage them to dig under the substrate.
It’ll take time to train hermit crabs to sleep at night, and you may expose them to significant stress.
Where Do Hermit Crabs Sleep?
Most hermit crabs sleep by burrowing themselves under the substrate in a habitat, which mirrors how hermit crabs sleep in the wild. They’ll start digging a tunnel in the early morning hours and prepare themselves for a day of rest.
Some hermit crabs take a different approach, opting to climb to the top of the tank and sleep while hanging upside down. This will make your hermit crabs resemble a colony of roosting bats. This is natural behavior, so do not be alarmed if this happens.
Ensure your hermit crabs have a soft landing if they fall from a ceiling while sleeping. Six inches or more of substrate will be enough to keep your hermit crabs safe from serious injury.
Do Hermit Crabs Sleep on Top of Each Other?
It’s common to find a colony of hermit crabs piled on top of each other while sleeping. This is also a holdover from life in the wild.
Hermit crabs are at the bottom of nature’s food chain and seek safety in numbers while sleeping in case predators discover them.
How Many Hours Do Hermit Crabs Sleep?
Most hermit crabs sleep for between 6 and 8 hours each day. On a long, hot summer’s day, your hermit crabs may stay asleep for longer.
Like mammals, hermit crabs are governed by circadian rhythms, so they’re unlikely to stir until the light dims and the temperature drops.
The reverse is true during the winter, as hermit crabs become active earlier as the days grow shorter and the nights extend.
As long as you provide lots of recreation for your pet hermit crabs within a habitat, they won’t have any objection to being awake for longer.
My Hermit Crabs Aren’t Sleeping
If your hermit crabs are active all day and night, something is amiss within their environment. Prolonged inability to sleep causes hermit crabs stress and eventually makes them sick.
Possible explanations for hermit crabs failing to sleep include:
- Lack of sufficient substrate to burrow and feel safe.
- Excessive light in the habitat.
- Insufficient humidity makes breathing difficult and causes stress.
- Background noise makes hermit crabs confused and anxious. According to Animal Behavior, noise pollution leaves hermit crabs disoriented.
- A lack of territory to sleep suggests the habitat is too small.
Emerging for a snack isn’t a cause for concern, but hermit crabs need a full day of sleep to flourish.
My Hermit Crabs Have Been Sleeping for Days
If your hermit crab seems to have been sleeping for much longer than the usual 6–8 hours, you may grow concerned that it’s sick or dead.
If a hermit crab is stressed, it will barely emerge from under the substrate. If you’ve recently bought a hermit crab home, it will undergo post-purchase syndrome (PPS) – a period of intense anxiety where it remains out of sight as much as possible.
Check the substrate of your enclosure carefully in the morning if you never see your hermit crab. You may notice tracks that suggest the hermit crab does emerge but chooses to do so while you are sleeping when it feels more secure. Given time, PPS will pass.
It’s also possible that your hermit crab isn’t sleeping but molting. All hermit crabs need to periodically molt their exoskeleton and grow a replacement. In an adult hermit crab, this will occur every 18 months.
During molting, a hermit crab won’t emerge from the substrate for weeks, or even months, until its new exoskeleton is fully formed and hardened. Never disturb a molting hermit crab.
How Do You Know When a Hermit is Sleeping?
Hermit crabs don’t snore, so it’s not always apparent if the animal is asleep or hiding. If the sun is out, the room is bright, and the hermit crab isn’t moving, it’s fair to assume it is asleep.
Most hermit crabs can’t resist the scent of a favorite food, so if you feel that a hermit crab is awake but hiding, place a snack with a strong, sweet aroma in the habitat. If the hermit crab is awake, it’ll emerge.
Also, applying a gentle misting in a hermit crab habitat will stimulate its senses, as will the presence of renewed saline water.
Do Hermit Crabs Sleep with Their Eyes Open?
Hermit crabs close their eyes while sleeping. If they’re burrowed under the substrate, this protects them from sand and other irritations.
You may mistakenly believe that your hermit crabs are sleeping with their eyes open as their antennae continue to twitch while sleeping. This is because hermit crabs remain alert to potential danger.
Do Hermit Crabs Leave Their Shell to Sleep?
No hermit crab will leave its shell to sleep. They’re most vulnerable while sleeping, and evacuating a shell makes it easy for a rival to lay claim to it without a fight.
It’s likely too hot for the hermit crab if it’s climbing out of its shell to sleep. The maximum temperature in most enclosures should be 84OF, so drop the heat by 5OF to see if this helps.
If hermit crabs live in conditions below 80% humidity, their gills dry out and close up, leading to difficulty breathing and eventual suffocation. The hermit crab may leave its shell to breathe easier.
Hermit crabs feel comfortable with a regular sleep schedule, so avoid forcing them to become active outside of nocturnal hours.
