A similar experience has started in the last month to affect me while I am awake as well. It has happened twice while I was sitting on the couch playing a game on my iPad. Again, I swallowed but I also started coughing afterwards. It was like a swallowed something hard or a glob of saliva and it went down the wrong way.
Correct me if I am wrong, but I believe the trigeminal nerve controls our ability to swallow. I know that I have had some trigeminal nerve damage from all the surgeries that I have had, and this nerve damage may be the cause of this sensation.
If you have experienced something similar, please post in comments. Thanks! I will ask my surgeon about this at my appointment on Monday and let you know his response.
UPDATE: I asked my surgeon and he said at night, it may be due to my snoring. I don't think I snore - I never heard myself snore, but then again my husband begs to differ! When I snore, my vocal cords get dry and swollen. I attempt to swallow in an effort to moisten and soothe them. The feeling is due to swallowing with swollen vocal cords.
During the day, it may be due to post nasal drip that happened to go down the wrong way when I swallowed.
If you experienced something similar and have a different answer from your doctor/surgeon, please let me know what he/she said in comments.