Sleepless night

13/06/09 after 12am is already 14/06/09

Im playing online game with my sister till about 1am i got tired and when to sleep my sister go on playing. i don't know why i just can't sleep i close my eyes turn here and there many time on my bed but i just can't fall a sleep. I open my eyes look at the close is 2.30am but sleep can't sleep so i started thinking what did i eat or drink that make me can't fall a sleep? I remember i had 2 cup of ice lemon tea during dinner time but i have just 2 small cup of it only??? I had drink a botter of ice lemon tea but i still can sleep well at night so what is the reason???? I really don't but what i know is the next day i will feel really tried when working.