All of the above is useful - but so is some forced ventilation from in the house to the outside - whether it's into the ceiling space or straight outside.
In a previous home, I installed a reasonably high volume exhaust fan in our bedroom - exhausting into the ceiling..... then had vents to ensure good ventilation out of the ceiling space - the whirlybirds would work well there.
As soon as the temperature outside the house dropped below the inside temp, we would turn the exhaust fan on.
Make sure you close the door and leave the window open - preferably a window across the other side of the room so it is drawing air across your bed.
If it is in a low humidity area, putting the sprinkler on outside the bedroom acts as an evapourative air-cooler.
Generally, we found we had to turn the fan off around 2 or 3am because it was getting too cool. I did play round with a speed control on the fan but I am not sure they like that.
There are commercial varieties of this to cool the whole house - using a 900mm fan running at low speed but they are around $1,000 plus. My exhaust fan cost about $80, and costs peanuts to run.
The only disadvantage was a bit of noise and a gap in the ceiling letting winter heat out.
It had the advantage of cooling the roof space and giving a "breeze" if I was working up there.
