THERMOREGULATION
The recommended temperature range for the hamster is 20-24° C, with a relative humidity of 54-55%. As they are nocturnal, the best photoperiod for optimal reproduction used in laboratories is 14 hours night and 10 hours day.
This is in contrast to other rodents, which do better with 12 hour periods. Photoperiod appears to be mediated through the pineal gland. Despite their dozy appearance by day hamsters are extremely active at night. In fact, fit hamsters have been known to travel several kilometers on an exercise wheel.Hamsters have a patch of brown fat over the scapula blades that extends from the cervical to the mid-thoracic region. In the abdominal region the adrenal glands, renal hila, and parts of the ureters are also sheathed in brown fat. During periods of cold the rich blood supply to this tissue increases and the weight of the tissue increases (Hoffman 1968). Tissue protein levels increase while fat levels decrease. The reverse happens in warm weather (Bivin et al. 1987).
Hibernation
If environmental temperatures are lower than 5° C hamsters can enter a temporary hibernation, thus lowering their body temperature, heart, and respiratory rate. They can, however, remain sensitive to touch during this period (Lipman & Foltz 1996). This pseudo-hibernation can also be stimulated by shorter day length and less light. The converse can also be true in that, exposed to warm ambient temperature, the hamster will go into a deep sleep - and if aroused suddenly will be most pugnacious (Hoffman 1968).