[SPOILER] You know you've played too much Amnesia when...

[Romulator]

1. You hear moaning from your basement.
2. You leave phonographs for yourself.
3. You drink odd substances and pass out.
4. You make heavy breathing noises in the dark corner.
5. You throw a chair at someone to make them run at you.
6. You play the terror music running through a maze.
7. You treat water as Laudanum.
8. You hold your left hand only up a little into your eyesight.
9. You leave a note here and there to say what you did a week ago.
10. You contribute more to this thread, just for laughs.

[PutraenusAlivius]

Just 4), 7), and 8).

EDIT:
Ooooh, and reluctant to enter a dark room.

[Kman]

i already do 4 it's the only way i can enjoy listening to gnaw their tongues

[rtjhbfvsrry]

You start chattering your teeth relentlessly in the dark.

[FlawlessHappiness]

Throw chairs around your livingroom, searching for tinderboxes and oil.

[Nice]

when you keep opening drawers and closets for no reason

[Tiger]

Throw chairs around your livingroom, searching for tinderboxes and oil.

when you keep opening drawers and closets for no reason

Haha, best ones!

[Brosive]

When you start talking like Daniel.
(I actually did this for about a week after I beat the game.)

[The chaser]

When you hear the grunt danger music when you see a politician in the TV.

[Wapez]

You know you've played too many retarded custom stories when you're afraid of picking up keys.