I use my fleece jacket for my pillow.  My sleeping bag comes with a little pocket at the head of the bag to stuff your clothes in to use for a pillow...or to stuff your pillow in if you must, I suppose.  Turns out the fleece jacket fits perfectly and does a pretty fair job of mimicking my pillow at home.

I used to use my life jacket but just never could get comfortable with it.  And when I switched to using clothes, that worked reasonably well early in the trip, but the later in the trip it got, the smellier they got.  By trip's end, it was usually back to using the lifejacket.  ;D

But that heavy fleece jacket really does the trick and it's a double-duty item on cool-weather trips as well.  On hot trips, I bring it anyway 'cause with the weather up there, you just never know...