I have insomnia something fierce at times, and yes, just once, I have fallen asleep in my T's office. I hadn't slept the night before, and it was an emotional session. She sat by me on the couch and put her arm around me. I laid my head on her, and pretty quickly cried myself to sleep. She woke me up after a short amount of time as my session was coming to an end. I know I have to feel safe to sleep...and I have also fallen asleep during reiki sessions (she says that's not uncommon), and in one of my recent hour and a half long meditation classes I caught myself doze off a couple of times. But it was after a couple of nights of no sleep. So yeah, I fell asleep during session once, and she just let me be until it was time to go.