As a short term quick fix to reset your sleep pattern you could try Restavit. It’s over the counter and basically a strong drowsy antihistamine. It’s a bit unreliable for me but I have weird reactions to drugs so it might be worth a shot. Definitely try a half tablet rather than a full because it leaves a groggy hangover.

For long term issues if you’re able to get in through the public system it might be good to have a sleep study to check for sleep disorders. Things like sleep apnoea or delayed phase sleep disorder.