I LOVE sleeping with my windows open. It was great when I had a two story home and didn’t even have to think about the windows being open on the second floor away from anything that could be a makeshift ladder.
Now that I have a ranch home and my room is on the ground level, I had to figure out how to sleep with my windows open safely. There are all sorts of locking mechanisms available for windows these days. Here are two I found on Amazon after a very quick search.
Double hung windows 
Casement windows 
My windows have locks built into them so they can only open about 2", which is just fine with me for a good nights sleep. Yes, they can be broken, but by the time it’s broken and someone’s trying to get through the window, they’ll be in for a surprise as the woman who lives there is armed with a pitbull, german shepherd, two attack cats, a 6’4" biker boyfriend and a Sig.