Hamsters are nocturnal animals widely used in circadian rhythm and metabolic research. Standard laboratory practices frequently disrupt their natural activity cycles, creating welfare problems that also affect research validity.
Hamster welfare in laboratory settings is challenged by the mismatch between their strict nocturnal biology and typical laboratory schedules. Animal care, experimental procedures, and disturbance during the hamster subjective night — when they should be active — impairs their rest and disrupts circadian biology. This circadian disruption compromises the very biology that hamsters are often used to study, creating a welfare and scientific validity problem simultaneously. Male hamsters cannot be socially housed without severe welfare consequences from territorial fighting. Females, when group housed in appropriate conditions, show better welfare indicators. Running wheels provide essential voluntary exercise outlet for these highly active animals. Temperature management is also important — hamsters enter torpor below certain temperatures, which can be an unintended welfare harm or experimental confound.