Wild hamsters fall into a life-saving deep sleep if temperatures fall very low, or if food becomes very scarce. This is what hibernation is all about - saving energy until the good times return.
However, there is still debate amongst hamster experts about whether or not captive hamsters should be allowed to hibernate. Generally speaking, owners do not allow their hamsters to hibernate, as there is simply no need for them to do so. There are also concerns about the effect hibernation has on pet hamsters, as the animals' bodies are not used to the processes involved with the transition into hibernation.
Also, given that these furry friends have short lives, why would you want to miss out on your time together by helping hem into an assisted state of hibernation?
Hamsters can go into a very deep sleep - something that saves their lives in the wild
If your hamster does go into ‘hibernation’, it can be quite alarming. He will be cold to the touch, and limp, giving every sign of being either very unwell, or dead. However, if you look at him very closely, you'll notice small, shallow breaths. Place the hamster back in the enclosure and move the unit to a warm spot in your house. This isn't to keep him warm during his winter snooze, it's to wake him up. Once he's stirred from his super-nap, he should be back to normal within a few hours.