Hamsters are popular small pets, but commercial cages are often far too small, and their natural nocturnal behavior and territorial needs are frequently misunderstood, leading to widespread chronic stress.
Chronic stress from inadequate housing is the most pervasive welfare problem in pet hamsters. Stereotypic behaviors - repetitive, functionless movements like bar-biting and circling - are welfare indicators that have become so normalized in hamsters that owners rarely recognize them as problems. Research by Dr. Georgia Mason and others has demonstrated clear links between cage size and hamster welfare. Waking hamsters during daytime sleep causes stress and disrupts circadian rhythms. Several European countries have set minimum legal cage sizes for hamsters that are far larger than typical commercial cages.