Yeah. It's weird though...if temperature is the "problem", and it's 88-90F inside his box, and I'm putting food inside, then why isn't he eating it? It must be something else besides just temps.
It absolutely IS more than just temps. Same thing with all the Testudo that want to hibernate, even though they live completely indoors in well lit, warm enclosures. Tortoise just "know" its winter. I think the shorter daylight hours have an effect, in addition to the temperatures.