Screen effect question

[RavenC]

So I realise that this thread is outdated, but I made an account especially to answer this very question.

First of all, I'll post a link to a print screen of the effect that I believe you mean.
http://i1097.photobucket.com/albums/g359...017a56.png
(location Prison, according to the person who was playing this is the room across the room with the hammer.
source: http://www.youtube.com/watch?v=MdqaY5xd_HI )

Now onward to my explanation.

Let's start of by checking what the Amnesia wikipedia has to say about this effect:
"If Daniel's sanity is quite low, in rare occasion the screen goes red and he can hear the Shadow roaring at him when he's going to finish some of his task, like when he is in the Orpiment room in the Wine Cellar or when he burns the coals in the Machine Room." ( source: http://amnesia.wikia.com/wiki/Sanity ).

However you said you were in a bright room with crystal clear sanity.

My conclusion is that the wikipedia can be considered partially correct.
When I played the game (I've played it 4 times with different people) the red light would never appear at the same point and it was only accompanied by low sanity once. So obviously the very first part is incorrect.
The rest however proves to be true. What I think happens is that you are making too much progress in one go.
It's the games way of trying to tell you to either stop playing for a while or to scare you into falling into a trap nearby (for example the monster on the staircase near the room with the acid or the glass jar).

In support of my thesis: I encountered the red screen only when I didn't die for 10 (?) minutes or so and continuously made progress.
In the storage room, when you get the drill parts and the rods within a relatively short period of time and you are not detected by any monster. The screen will be likely to turn red as the scripted monster appears after you pick up both rods.

It could be that your bright room is close to a trap. One thing is for certain though, you're going the right way.

I hope this answers your question!
Again I'm sorry for replying on a thread that seemed to have died about a year ago, but it bothered me that no final answer had been given.