Perhaps there is a lack in your keeping.
I've kept retics, never had one bigger than about 22 ft, but once they hit the 12 to 14 foot mark they were markedly less active. Maybe yours are hungry.
You may want to rethink your closet analogy too. Without sunlight most diurnal mammals would not last long for more reasons than need discourse here and now.
Again, comparing mammals to reptiles is adding value how?