Will something other than sleep apnea cause me to wake up at night gasping for air?

Yes - reflux . Stomach juice can come up into your throat while you lie down and sleep. Gravity is not your friend when you lay down and in certain people stomach juice can come into the throat leading to coughing, choking, gasping and even temporary inability to breath. If this is happening to you please see an ENT doctor to have your lower throat area looked at.