Baby cannot sleep in aircon room

My husband and I did an experiment, and realise our baby sleeps better without the aircon. When sleeping in an air conditioned room, she makes alot of incomprehensible sounds and her quality of sleep is rather bad. Note that the temperature is set at about 26. We have been sleeping without the AC these few days and we realise she stopped making those sounds, and is sleeping better. Anyone knows why is that?