On my most recent journey, using a rue+p. cubensis tea I encountered a
similar buzzing sound keeping me awake for hours.
The beginning of my trip was excellent. We started at 9:00pm. Nice visuals,
and lots enlightening thoughts. The sound didn't come until I tried to go to
sleep at 2:00am. I don't normally notice it under normal conditions.
However, with my eyes closed the sound was DEAFENING. Drove me nuts because
I couldn't go to sleep. So rather than fight it, I got rid of the sound by
thinking. Of course I couldn't go to sleep while I was thinking, but it was
better than listening to the deafening roar of silence in my head.
My first thoughts were of the sound. I came to the following conclusions. I
only heard it when my mind was blank. I have since labeled it the sound of
silence. The sound also had a visual pattern which was interesting to look
at. When I looked at it long enough, materials manifested in the pattern. I
could see events unfolding, places, people, etc.
I think the mushrooms kept me awake with this sound, and the sound made me
think. I haven't suffered from light episodes of insomnia since my
childhood. But I believe that these periods of lying awake at night thinking
did a lot for my development.