Suggest Treatment For Insomnia

Hi doctor how are you doing .I am 28 yrs old.I go to the gym at 8 pm everyday and I use pre workout before I go which obviously contains caffeine .now my problem starts in the night as I go to bed at around 2 am and end up not sleeping til 5 -6 am which is really frustrating. I have tried restyl .25 my say about once or twice a month which fairly put me to sleep but I don't want to use it as I believe it is additive and also not very safe for the body .can you please suggest me a solution for my problem.also like you to know that it is not possible for me to go to the gym in the morning or little early.thank you in advance