Oh dear, in my experience snacking at night is one of the most difficult habits to break. MRSROK's advice to try a non sugary snack is worth a try, as it sounds like this is a carb craving rather than real hunger. Perhaps you could gradually reduce the biscuits to a less carb heavy alternative? As this carb-hunger usually comes in waves, perhaps if after your snack you could distract yourself with a task for twenty minutes or so, the worst of the hunger feeling might pass.