Contributors to this thread:

A frozen 0.33 or 0.5L PET water bottle wrapped into some cloth is the most effective and cheapest trick I learned to get well through >25°C nights in my rooftop flat.

If you struggle with the heat, try it out! In my experience this is about as good as a ceiling fan, a lot better than table fans and a lot cheaper!

Credit, where credit is due. This came from the amazing #LowTechMagazine. Last paragraph is about "the cold water bottle": https://solar.lowtechmagazine.com/2022/01/the-revenge-of-the-hot-water-bottle