I get this too and yes there is a lot of debate to what causes the voices one being a form of hallucination-I cannot remember the proper term for it. Like you I have experienced it all my life. I once mentioned it to a medium and she said that she also gets this and as far as she is concerned it is spirits speaking. She said that all of her medium friends don't get this and she was suprised to be speaking to someone who also hears these night time/early morning hour voices. Like you, she and I thought everyone experience this. I do know on this forum there are quite a few who experience this too through.

I also hear music. singing, and general talk as if there is a couple of people or a group chatting away. At first I would just get snippets before I would fall back to sleep. I hear these voices etc when I am inbetween the sleep/awake stage and I have learnt to stay in this stage for sometime now before falling asleep so I am now hearing more then snippets and sometime full sentences which are always coherent and in context. I have also heard people speak in a foriegn language and the only language I speak is English.

But who knows. I also do not find these voices threatning and find that listening to them actually helps sooth me to sleep in a odd way.