Unable to fall asleep 24 year old male please help!

Hello, my son, who is 24 years old is struggling with being able to fall asleep at night. Hes been dealing with anxiety and hyperactivity for a while and was treated with Lisinopril and Gelsenium in the past. Lisinopril was not a good match, making him jittery and causing nightmares at night. He stopped taking all homeopathy about 2 years ago. Lately, hes been having trouble falling asleep at night, saying that his brain is hyperactive and he is tossing and turning, sometimes not able to fall asleep until 4-5 in the morning. He adjusted his schedule to be able to go to bed around 10-11 each night and it worked for a bit, but now back to the hectic nights. He works long hours sometimes and gets stressed during the day. Any advice on what remedy suits better, would be appreciated. He is lean, eats healthy, average height, active, dark brown hair and eyes and he is medium skin color, not super fair. Thank you in advance for your help.