I had this issue too. What's worse, is that if you don't move around much during your sleep, the room is under the impression that you were not there anymore and the air-conditioner would turn off. I recall during my last (and final) experience at this Westin I woke up in a hot sweat multiple times during the night, every night, due the air-conditioning turning off.

At many properties with movement sensors, the air conditioning, exhaust fans and wall outlets are not connected to the circuit that switches off when the room is inactive. It seems the guest rooms here may be poorly configured in an effort to conserve power at the detriment of guest experience.