So I've been doing a bit of testing to see how comfortable and manageable it is to spend the whole night in a tight straitjacket position. To simulate a straitjacket I simply take a sweatshirt, and then tie the sleeves together with some string/rope like this:

The shorter you make that space between the two sleeves, the tighter it will be. This is probably the biggest you want it, as any more and it isn't really restrictive, too short, and it is very uncomfortable.
Here is a short video I made of how it works:
https://streamable.com/30e2If you can't tell, all I am doing is crossing my arms in front of me, then passing the loop created over my head and behind my back, then sliding that down. This is also semi-easy to get out of, depending on how tight you make it, it takes maybe a minute or two to get out of.