Not hungry anymore

I have sleeping problems and have for years. I am 17 almost 18. I havent been able to sleep more than 5 or 6 hours for the past 3 or 4 years of my life but have adjusted to my 4 hour average. I am a hyper person and dont get tired from lack of sleep but lately my lack of hunger has been puzzeling me. For about 2 months maybe 3 I have been able to go a day or 2 without eating and not realizing i havent eaten because i am not feeling hunger My stomach doesnt growl and i dont get cramps. I just dont get hungry and dont eat excessive amounts. I never liked junkfood and eat alot of healthy foods and raw veggetables. What could it be?