Welcome to TT. Ear infection is quite common cause of T and sleeping time is often a time when T is loudest. Sometimes it is due to the body posture of sleep or blood flow to the ears. Sometimes it is due to the sleepy state of 'Awakening Response'. This is particularly bad for taking short nap. Dr. Nagler has written about this as below quoted:
"I have always felt it to be due to the role of the reticular formation in tinnitus perception. The reticular formation is a primitive structure in the brain stem. It's a "vital sign monitor." When you wake up, the RF checks to see whether or not you are alive! It looks for heartbeat, respirations, blood pressure, temperature - basic bodily signs. It does not care whether or not these signs are good or bad - just that they are present. And as far as the RF is concerned, tinnitus is part of "expected" body function in an individual suffering from severe intrusive tinnitus. So when you wake, your RF checks to see whether or not tinnitus is present. And if it doesn't immediately find the tinnitus, the RF seeks it with a vengeance - - especially in the post-nap state, when there has been inadequate REM sleep and when, therefore, the RF is on already "high alert" that something might not be quite right. Theoretically - very theoretically - this RF hyperactivity in seeking tinnitus, which in a person with severe intrusive tinnitus it equates with life, results in temporarily markedly augmented tinnitus perception."