Got to love this subject lol, I used to just do the use my clothing and what not but I have recently purchased a thermarest down pillow.
Omg it's so nice and comfy, you can adjust the firmness as well by adding a few bits in its 'pocket' this is also a nice way to wake up to warm clothing to lol.
It's amazing how much of a difference a pillow can make, good sleep good morning good hiking 👍