100% cotton Percale! Feels super crisp and cool to the touch More on reddit.com

I have terrible hot flashes and have found the coolest material to be TENCIL sheets. They breathe and aren't scratchy in the slightest. I don't know where to find them for a fitted sheet only. Good luck! More on reddit.com

It sounds like you might have more of a problem than just the sheets. What sort of mattress do you have? I know you say you're on a budget but the best advice I can give is never go cheap on anything that your nights sleep depends on. As a nuclear furnace sleeper myself the only solution I eventually found was to use a Dunlop latex mattress topper - they're full of holes and micro pores that basically let the air flow underneath you instead of allowing heat to build up. Stick a 100% cotton sheet on top and that's as cool as it gets imo. It's not a cheap fix (a 2" latex topper will set you back at least a couple hundred bucks even without a cover) but it's worth it. More on reddit.com

You will get a lot of different answers here, but I will always maintain that quality Linen sheets are the best at regulating body temperature. No matter what is suggested here, avoid high thread count cotton/sateen materials as they do not breath well, which you need for temperature regulation. Linen can absorb far more moisture from your body than cotton, bamboo or most other materials, which in the end is what you want. Other materials feel cool initially, but as you perspire over night they will become clingy. My wife and I have tried a lot of materials and after getting good Linen sheets, we will never go back. They are pricy, but you spend 1/3 of your life in bed. They also work well in the winter for the same reasons. They will also last for decades, unlike most other fabrics. More on reddit.com