I'd try that, but I know I had trouble sleeping after the surgery as well, whether I napped or not. I still do (witness that its' 3:20am here).
My GP theorized at first that I was releasing a lot of energy as I lost weight - ie, I was used to sleeping more than normal before surgery, but as I lost weight I had more energy to do things and didn't need to sleep as much. He still thinks that's the issue, and in reality I've been in bed since 10 so I've gotten 5 hours which is more than a lot of people get.
I'm thinking I'll start going to bed around midnight.
But I do remember immediately post-op, I could only sleep about 3 hours at a time regardless of whether it was day or night.
Best of luck to you. Congrats on making and following through with a major, life-changing decision. Even if you can't sleep for a while, you won't regret it (the surgery)!!!!
"When someone shows you who they are, believe them." ~ unattributed