Recent research has shown that "C. medius" hibernates (or aestivates), even though in the tropical winter of Madagascar, temperatures remain high. It is the first tropical mammal and only primate in which hibernation has been demonstrated. However, the Malagasy winter is dry, and it appears that the lemur is avoiding the drought. It can hibernate for seven months. Unlike animals that hibernate in temperate regions, the lemur does not control its body temperature while hibernating, and if the tree hole in which it is sleeping is not well insulated, its body temperature fluctuates in accordance with the outside temperature. During torpor, this lemur has been found to periodically enter REM sleep; non-REM sleep has not been observed, a pattern opposite that found in hibernating ground squirrels. The REM sleep episodes occurred during periods of higher ambient temperature (averaging 27 C, versus an average of 20 C during nonsleeping intervals while in torpor).