this regularly happened when i was at uva, and two cities later, i regret to report, still continues to happen: von would call me at two in the morning on a night i had gone to sleep early for a change, and keep me talking until gradually from groggily mumbling i became more lucid and then just as i become wide awake and think of a dozen sensible things to say to him he would hang up on account of phone battery running out/needing the bathroom/wanting to go to sleep and leaving me perplexed and unable to return to sleep.