What's going on as I fall asleep?

This sounds like hypnagogia, or hypnogogic hallucinations, which usually occur in the first stage of sleep, when you are just drifting off to sleep. This phenomena can include many sensory experiences, including sight, sound, and feeling. Often, the images seen are fleeting, rapid to change, and aren't always full images. Sounds can vary from quiet to loud, and can be nonsense banging or even full conversations. Common feelings are tingling, numbness, like the person is falling, floating, or suffocating, and more. Since it is only the first stage of sleep, you haven't fully slipped into unconsciousness and can be aware of this happening. In fact, 60% of people report experiencing this at some point in their lifetime, and 6% report having this experience regularly. Hypnagogic imagry can also occur when just waking up as well as when falling asleep, and is often accompanied with sleep paralysis, which, if you stay conscious during it, can lead to a lucid dream. I have experienced this several times, in the morning and at night. One night, I "heard" a long conversation about tennis. I could shift positions and it would stop for a little bit, but as soon as I stayed still long enough, it would come back. Sort of annoying, but oh well. I hope this answer has helped :) ~Ceci