I tend to thrash in my sleep. Don't know why and my fitted sheets were always coming unglued in the middle of the night. It was a normal morning when three corners were off and it looked like a tornado had gone through my bed.
So I bought a set of these
https://www.amazon.com/dp/B0942R3MJN?psc=1&ref=ppx_yo2ov_dt_b_product_details and man they have changed my life. Not only do they keep the fitted sheet where it's supposed to be but my thrashing has died down. I stay on 'my' side of the bed and making it in the morning is just a matter of pulling up the flat sheet and the comfortor, arranging the pillows, and I'm on my way.
Better thing is at night when I hit the pillow my bed is nice, tight, and arranged. It's like sleeping in a 5 star hotel every night.
Can't recommend these puppies enough. So much so I'm going to go ahead and get some for my flat sheet