I often wake up from sleep with a headache?

I sleep in a very humid room, it's rarely is cold because I'm on the top floor and "heat rise." Even with the air conditioner on it will still be humid in here. I was wondering if it's abnormal to wake up with headaches after sleeping in a hot 87 degree room, and if so, why do I get them? I also get heat flashes after I've waken up from sleeping.