[A firm nod, and then a sigh. He's still pretty unsure about the whole situation, and it doesn't sit well with him that he probably sounds like a nutcase, or some naive person jumping to conclusions.]

I was returning home after spending some time investigating. Everything was normal, but then all of a sudden, I couldn't walk anymore. I collapsed on the road and... [He trails off... but then picks up again with a shake of his head.] It wasn't sleep. It certainly wasn't exhaustion, I know what that feels like. This was different, I honestly... felt myself go.

After that, I woke up in my house. A whole day has passed, too. ... There's also this.

[And he holds up his wrist for the Doctor to see the mark.]