Melatonin can mess up circadian rhythm over time. Doctors talk a lot about sleep hygiene and being very regimented about it. I take Unisom to help sleep sometimes but I generally try to stop drinking caffeine early, not eat too late, make bedroom as dark as possible, imagine myself floating calmly in my bed (weird but I've done it since diagnosis and it helps me not be totally sleep deprived everyday), valerian tea is helpful, passionflower tea is helpful. Writing down things that bug me before I get cosy in bed to not have to have it persisting in my head all night.