Duvets are just a little too good at insulating... Not a big fan of swimming in my sweat on an overnight flight. Find a blanket you like, and bring it.

I used to work in Cabin Service Planning... If it's in plastic, it's been to the laundry. Question is whether or not it went thru the washer. Doing spot checks, we'd occasionally find blankets which had gone *to* the laundry, but were never washed before being fluffed & folded....

The commercial washers that they use for blankets are pretty good -- they're the same ones the linens go thru in most locations IIRC.

But nothing replaces your own security blanket...