I have begun to be confronted with this issue almost every night when I'm lying in bed. I'm thinking about something intensely and then my mind short circuits. I lose all recollection of it and I'm incapable of forming thoughts, feeling very exhausted. Last night I did feel frustrated forgetting something very interesting apparently and made an effort to try remembering tracing back the steps, I thought about this, then I thought about this next, mundane stuff, then the follow-up is left in the dark. Have you ever experienced something similar?