it’s like my body never lets me fall asleep

i’m currently in high school and no matter how hard i try i find it difficult to fall asleep no matter what, it’s at the point where i pull an all nighter without me wanting to about once a week, ive taken melatonin and it never really helped either. I really have no reason to be kept up, i’m pretty happy with where my life is at right now but still, i find it very hard to fall asleep. if anyone could give advice i would appreciate it a lot.