Is this a normal sleeping habit?

I am a nineteen year old boy who lives in the United Kingdom. I stay awake for five days, then sleep for three hours. I have done this since I was seven. Due to this I drink quite a bit of coffee and eat a lot of sweets to keep me going through out the days. I am underweight though. I am 5'6 and I weight 98 pounds. My brother says if I countinue this I will end up dying or getting sick. Though to me, it is just what I feel most comfortable with.