Be very careful, as always when tired, when at the Crossroads in Moria. One fall into the well and you fall.. not to your death... no, much worse. You fall into the Waterworks, a place that during my first stay was pointless and gave me hours of wandering to try to find my way out - then out of that out to get back into Moria proper. I'm sure I'll have plenty of reason to get back down there eventually... but when I accidentally found it, it was NOT what I wanted.
The real lesson? Stop trying to play when I'm dead tired. Running to my death off cliffs is bad enough, but Moria is a dark dark place... getting lost in the dark is well, it worked well for Bilbo and finding preciousssssss, but the rest of us have normal hobbit luck.