Ok hard to pinpoint potential issues without seeing your diet, but this is what affected my sleep (and quite severely so):
I learnt not to eat coconut butter after 3 pm. If I do, I wake up at 2 am and stay awake.
Not to have my fish oil later than 5 pm. See above, same issue.
I started taking magnesium 2 hours before bed and that really helps. People here swear by Natures Calm.