Buy air con.
Wet your PJs and put them in the fridge for a couple of hours before bed.
Open the windows in the early morning to let cold air in then close windows and curtains / blinds to keep it cook.
Agree with having a hot drink, and sip room temp water.
Your body is concerned with keeping your 'core' at the same temp at 37 degrees. Your core is lungs, heart, stomach, brain etc. To cool the core your blood vessels stretch a bit and more blood is circulated near the surface. You sweat, as the sweat evaporates this cools your skin which means the blood near the surface can cool.
If you have a cold drink your core immediately notes decrease in temp and reverses the cooling process.
Obviously there are various physiological processes but that's the basic idea.
The opposite happens with cold, which is why mountaineers lose the odd finger.