Happy in small cage, stressed in big cage.

[Fluffagrams]

How long have they had the hamster and how old is he/she?

I've had a fair amount of experience with hamsters who have been unhappy in larger cages to begin with but after a few weeks in a smaller cage, adjusting to living alone, they have settled enough to be upgraded to something larger.

There are some hamsters that prefer smaller spaces though and if after trying the usual suggestions to help the hamster to settle, they're still unhappy then it's kinder to let them live in the cage where they are happiest.

The way that I usually look at this situation is that hamsters can't read... they don't know what cages the internet says they should be happy in but what they do know is how they feel about their environment and as responsible owners we should be providing them a home that allows them to live freely from fear or distress.