system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 : why is a room heated to 65 quite comfortable, but a room cooled to 65 is freezing!?!?
gpt
Temperature contrast and adaptation difference.

When the room is heating, your body adapted to the cooler temperature, thus it relaxes and your blood vessels slightly expand (they were contracted to lose less heat). When the room is cooling that means your body adapted to conduct more temperature (expanded blood vessels to prevent overheating) and cooling brings some shock, thus your vessels have to contract due to the potential risk of freezing. 

Same goes with contrast showers — you alternating hot and cold water, thus providing a slight thermal shock to the body. It may be good for your blood vessels tonus, but some people may suffer panic attacks because of them.