Grimrock

It seems the deeper into the dungeon I get, the faster the torches burn /and/ the faster the "light" spell fades. Is this just my imagination or is there something to this? Also, if this is true, does food dwindle quicker the deeper you go also?

It's just you.

It's possible you are sleeping more often to regenerate health/mana later in the game - while you are asleep, time passes at a faster rate (so torches run out faster and food goes down quicker during resting!).