text: why do i get cramps in my calf muscle  when i sleep wtih the air conditoner on? with the temperature soaring, i am left with no choice but to switch on the air conditioner before going to bed. but every day at around 3a.m  i get severe cramps in the right leg  and am forced to get up, massage my leg and relieve the pain. why does this happen? is it rheumatism? what is the remedy other than switching off the a/c? from my experience, "charlie horses" are not related to temperature. i was told they are caused from dehydration. you may also have restless leg syndrom, which they do have medication for to alleviate the pain you have in your legs. i suggest you see a doctor. good luck. :)