What does 'dreaming' and talking while awake indicate?

My husband has started to spontaneously fall into 'dreaming' and talking while seeming to be awake. While watching TV or at the computer he will suddenly have a full-on conversation with 'whoever'. This can last for 30 seconds or 3 minutes. He remembers the dream and what he said. Sometimes he also has tremors/jerks. The past few days he has woken up at 2:00am, and gets ready to leave for work, not realizing the time, even when he looks at the clock. He had a recent bout of dehydration which led to a kidney infection. Blood tests last week indicate the infection has healed. He does have a history of sleeping only about 5-6 hours a night, then napping in the late afternoon. No sleep apena. Please help--I'm frantic. Thank you!