Net City

just came back from net city with my secondary classmate. I have a sickness everytime i go net city. I only can stay there like 1 hour then i will feel like vomiting and headache. I don't know why but i usual liao.. I feel i am more to nature side.. i can go out the whole day without feeling tired but i feel sleepy, headache and want to vomit if i sit inside net city just for 1 hour. I can sit in front of my lappy for hours without feeling sick or whatever.. weird huh?