You raise a lot of questions i.e. what type tortoise? What temps? What has changed recently that is different than last 5 years? Etc. Inappetance is a symptom that things have changed, and your tortoise may be too cool for normal behavior. So get the temps and light cycle adequate to stimulate rather than inhibit normal functions. Hibernate? Yes, it may want to do so since it apparently has no other choice. Do you offer it choices between warm and cool and dark and light, etc.? If you plan to hibernate it, you must prepare it, research hibernation and learn about it, done right, not an issue, done wrong, it may get sick or worse...read up on hibernation in a reputable text and search this often queried topic in the archives. Good luck, a change of behavior/feeding IS cause for concern IMHO. Vic H.