I tried an experiment with a friend who remains an inspirational and very penetrating poet a few years ago. Using a stereo mike and a video on long play I sound recorded his musings and ramblings whilst he experimented with certain substances of his choice over an 8-hour period.
Most of what was produced both written and spoken beyond the first hour was pretty much nonsense... However the experiment did yield one very fine stanza and the tape was then used to try and find inspiration for future efforts - I believe with some limited success.
This is hardly empirical evidence one way or another... partly because I could not think of effective way of coming up with a control model. 8 hours sat in a darkened room without the aid of some relaxants would hardly be condusive to good writing.
Anyway... there it is...
Hyp