During our sleep, we all travel. It's commonly called an out of body experience (OBE). If we travel consciously it is called astral projection. If you have more awareness of your body as you sleep (are a light sleeper) or you remember most of your dreams or lucid dream, you will be much more aware of what is going on and may be jolted by sensations.
When entering a trance many people describe it as a feeling of falling. Many times this very feeling is what prevents people from successfully projecting because they tense up or jump up. Coming back to our body can also sometimes feel like falling.
In conclusion, you are traveling in your sleep but the OBE that people generally sleep straight through is freaking you out and causing you to wake up suddenly.
You're watching too many scary movies of spirits lifting people into the air when they are sleeping. First of all, what would be the point of that? Secondly, when that happens on "based on true story" horror movies, tell me, how did they know they were floating if they were sleeping? Hehehe. There is a lot added to those things for a dramatic effect. The real stories aren't as thrilling.
I have experienced serious physical manifestation of spirits and I have never had a spirit make me levitate. If a spirit makes you fly, gravity is going to pull you right back down again just as fast. For the record a spirit has never made me fly and I wouldn't want one to. But I do know that in very dangerous hauntings, people can be thrown. But I'm sure your not experiencing a spiritual circus in your house. If you were, you would have much bigger problems then feeling like you're falling in the middle of the night.
If you REALLY think you were in the air, and I don't know what I'm talking about, why don't you video record yourself sleeping every night, writing over the same recording until you feel that sensation. Then, watch the video after you "fall". If you are floating, show me the video of you floating because I have got to see that!