As its a long term condition you need to take a counseling session from an expert.
Few tips you can follow :
1. During day time dont be anxious or stressed.
2. Try to keep your mind calm as much as possible.
3. You can finish all your daily works and be totally relaxed before going to sleep.
4. Avoid
sugar,sweets after dinner.
5. Have dinner atleast 2hours before you go to bed.
6. Maintain your sleep hygiene
Next Steps
If its worsening consult a counselor or psychiatrist before it leads to any other sleep disorder.