How long should I meditate to effectively improve my sleep?

Mujhe neend ki problem hai aur main jaldi so nahi paata. Main aksar 40 minute tak meditate karta hoon, par phir bhi neend nahi aati. Achi neend aane ke liye kitni der tak meditate karna sahi hai, ya kya 40 minute anxiety ko badha dete hain? My name is Prakash. My DOB is 10th May 1990, born at 5:00 PM, in Bhopal.