Is advanced sleep phase syndrome life-treathing? in fact, this makes me fully awake during my classes but in the evening i have big problems...

Try to treat it: Currently ASPD is not known to be more life-threatening than, say, obstructive sleep apnea. ASPD patients usually fall asleep between 6-8pm & wake up before dawn. Treating ASPD with bright light therapy in the evenings or with chronotherapy would be the most healthful approach for you. See a sleep specialist. http://www.sleepassociation.org/index.php?p=advancedsleepphasesyndrome