Tossing and turning causes breakage due to friction from standard cotton...

https://wiki-triod.win/index.php/How_to_Protect_Your_Hair_While_Sleeping_on_a_Budget_in_Australia

Tossing and turning causes breakage due to friction from standard cotton pillowcases. Switching to silk helps, but you can also try a loose braid or a silk bonnet to keep your ends protected while you sleep