Extreme dryness develops overnight, anyone else? (9 months post-PRK)

Wondering if anyone else has experienced this and might have some recommendations. I had PRK last December and so far so good, I'm extremely pleased apart from one thing.

Every night my eyes get so dry while I'm asleep, that sometimes opening them in the morning feels like someone ripped a band-aid off my cornea--the band-aid being my eyelid. I have to very slowly start working them until I can get some tears flowing and be able to open them without pain. Unfortunately, sometimes I inadvertently open my eyes in the middle of the night and boy is that unpleasant.

I thought I might be still healing, but I'm now 9 months post-PRK and this still persists. My doc gave me some ointment at my 3-month follow-up but that didn't help at all. I don't have any dryness throughout the day--in fact, dryness in general is far less than when I had glasses/contacts. Does anyone have any experience with this? Is this permanent? I don't regret the procedure one bit, just hoping to solve this if possible.