If you don't already, wear breathable pyjamas, and cotton bedsheet/duvet cover. And ideally, a non-synthetic duvet.
This will at least reduce the liquid sweat, by allowing it to evaporate better.

Keeping track on when it's hot/not/rainy can help get the house temperature under control.
When it gets cooler at night, you can open the windows to cool the fabric of the house down.
Then close everything up first thing in the morning, including south facing curtains.
The cooler you can get the house overnight, the more heat it can absorb the next day.

So here, I left the window open on one room, (red) and closed on another (dark blue and teal).
When the outside temperature (purple) dropped to 15 overnight, it dragged the orange room down significantly.
(Then I forgot to close the window in the morning, so it kinda got negated 😬)

Other than that, a dehumidifier may help if feeling less muggy, though it will raise the temperature of the room overall slightly, since it's going to use energy to run.
Externally run aircon is, unfortunately, the only real step beyond that. And it's a bit of a chunk of change (£500 for a basic DIY one, £1500+ for one room professionally).