Hello Pradeepa Ganesh
There are many reasons for problem sleeping.
This can be because of stressful lifestyle, hormonal imbalances, frequent changes in work shifts, and depression.
I see that you mentioned overwhelming negative thoughts that occupy your mind when you go to bed. This can be an early sign of depression. However, like I suggested earlier, there can be many other causes also, all of which are treatable!!
Next Steps
please consult a Psychiatrist for a complete evaluation of your problem
Health Tips
try to have a routine with
-moderate exercise regularly
-adequate hydration
-follow sleep hygiene
-breathing exercises for relaxation