Is it easier to get into trance when sleepy or tired?
Yes. Sleep deprivation is a time honoured method for achieving trance.
Being sleepy aids in relaxation, and the trance states we shoot for are part of the continuum on the way to sleep. However, the trick lies in not actually falling asleep but maintaining the place in-between.
That is the tricky spot right there. I get to trance easily enough but I have to keep my eyes open or its over for me.