Hamster hibernation

During the cold winter months, many wild animals hibernate, waking up when the external temperature rises again. But did you know that some pet hamsters may display a behaviour resembling hibernation, too?

If the temperature in the room where a hamster lives becomes cold enough, and especially if the room is dimly lit, or only lit for a short time every day, some hamsters may go into a state of greatly reduced metabolic activity, called torpor.

It can be rather a shock to find your hamster in this condition if you weren’t expecting it. Unsurprisingly, many owners worry that their hamster could have passed away.

So, how can you tell whether your hamster is just in torpor? Is it okay for them to do this or should you wake them up again? And how can you prevent your hamster from entering torpor?

When do hamsters hibernate?

Although we often use the word ‘hibernation’ to describe the inactive state some hamsters display, a more accurate term for this is ‘torpor’.

True hibernation is a state of reduced metabolic activity in which some animals have been adapted to spend the months when food is scarce, and temperatures are low.

During the months when food is plentiful, animals that hibernate build up fat reserves in their bodies. Then once the colder months arrive, they go into hibernation. Their activity levels drop, metabolism slows, and their fat deposits provide the fuel and water they need to take them through to spring. True hibernation is normal behaviour for these animals and it’s a predictable event for part of their year.

Do all hamsters hibernate?

Not all hamsters hibernate.

Some species of hamster (for example, the wild European or black-bellied hamster) are true hibernators and will sleep for long periods during winter.

Syrian and certain species of dwarf hamsters sometimes enter torpor for short periods of time if they are exposed to low temperatures, fewer than 12 hours of daylight per day, and if food is in short supply.

Female hamsters usually enter torpor for shorter periods than male hamsters do.

How long do hamsters hibernate for?

Domestic hamsters are no longer adapted to show true hibernation, because the artificial warmth and heating in a home means that their living conditions are much less variable. However, they can perform a sort of short-term ‘emergency hibernation’ when conditions are unexpectedly harsh for them. We call this state torpor (it’s also known as permissive or facultative hibernation).

Like true hibernation, torpor is a survival mechanism designed to allow the hamster to survive difficult conditions. Both torpor and true hibernation cause the heart, respiratory and metabolic rates to decrease and the body’s activity levels and temperature to fall. However, torpor is a short-term state that can occur whenever the external temperature drops or when food is in short supply.

Torpor can last for hours or days, ending when the temperature rises again, but it’s not designed to last for prolonged periods. Torpor is a survival strategy for when a hamster needs to make an unexpected shutdown to carry them through temporary harsh conditions. If conditions don’t improve, a hamster in torpor won’t have the reserves of an animal in true hibernation and is more likely to die from the cold or from dehydration, the longer torpor goes on.

Is my hamster dead or hibernating?

If you suspect your hamster may be in torpor, you can do some simple checks to find out. If your hamster is in a room where the temperature is over 20°C and they are not situated by an open window or other draughty spot, torpor is unlikely.

In a room where the temperature has become cold enough for your hamster to enter torpor, you’ll need to take a closer look at them to find out whether they are breathing. During torpor, they might only take a breath every couple of minutes, so you’ll have to watch closely for a few minutes to see a breath. You can also try holding a cold spoon or small mirror in front of your hamster’s nose to look for fogging as they exhale.

If you can’t be sure your hamster is breathing, you can try to detect a heartbeat using your fingers. Place the tips of your forefinger and thumb either side of the lower front part of your hamster’s chest, just behind their elbows. You’ll need to use enough pressure to notice if the heart does beat, but you don’t want to squash your hamster’s chest, so think about how much pressure you would use if you were holding them to look at them without them escaping, and that should be about right. A Syrian hamster’s heart is very small and, knowing that their heart rate during torpor drops from their usual 400 beats per minute to only 5–10 beats per minute, it can be difficult to tell whether their heart is beating or not. Try this for a few minutes as you might miss a heartbeat until your fingers are ‘tuned in’ to something so slight.

You can try stroking your hamster softly to see whether they twitch their whiskers slightly and you can also pull gently on one of their paws to see whether they give a little stretch.

A hamster’s body temperature will drop during torpor, so feeling cooler or even cold to the touch isn’t necessarily bad news, especially if they feel loose and floppy. If the room has remained warmer than 20°C and your hamster is cold and stiff, sadly, this makes it more likely they may have died.

The final way to check whether your hamster is in torpor or not is to increase their room temperature gradually to above 20°C. A hamster in torpor should wake up again after several hours to a day or two.

Should you wake a hibernating hamster?

In true hibernation, metabolism of the fat reserves built up over the summer provides energy and water for the hamster’s body to use during winter. Hamsters in torpor will not have spent months building up fat deposits in readiness for harsh conditions, so their limited fat stores can only provide for them for a short time. If torpor lasts for too long, hamsters may die from dehydration and lack of energy, finally succumbing to the cold.

So, if you discover your hamster in torpor, you’ll need to improve the conditions so they can wake up again.

If you know your hamster can only have been asleep for less than one day, you may be able to get them to wake up using gentle warming.

Safe ways to warm hamsters in torpor include:

Holding them gently in your cupped hand, so that your own body heat warms them
Stroking them gently can help to revive their circulation
Placing them in a nest of warm towels

Avoid placing them on heat pads or exposing them to anything warmer than your own body as raising their temperature too rapidly could lead to problems and pets who can’t move away from strong heat sources can suffer serious burns.

Make sure plenty of food and fresh water are available for when your hamster wakes up. If gentle warming alone isn’t waking them up, or if it’s been more than one day since you saw your hamster awake, you can also try keeping a bright light on for 12 hours, which should stimulate them to wake up.

Hamsters who have been in torpor for more than one day may have become dehydrated and low on energy supplies, so it’s a good idea to make an appointment for them with your vet as soon as possible so they can be checked and given any necessary support.

Can you prevent hamsters from hibernating?

If your hamster receives 12 hours per day of bright light and the temperature of the room where they live stays at a steady 20°c or above, and if they have an adequate supply of food, water and bedding, they shouldn’t go into torpor.

So, if you’ve made sure your hamster’s environment fits all the above criteria, you should expect them to wake up as usual every evening.

If your hamster’s behaviour changes, or if you don’t see them when you would normally expect to, check them gently to find out how active they seem and always contact your vet team for advice if you notice anything out of the ordinary.