I had a concussion about 13 years ago, and I still have all the symptoms of PCS. I have been trying to figure out how to fix these things like the sleeping and attention issues, I have been on the internet hours at a time looking this stuff up and I have read that PCS symptoms can be permanent. It is very rare and hard for me to tell cuz I had the concussion when I was like 4. So I believe it is possible for PCS to last 13 years. :)