What’s your best sleep biohack that knocks you out cold?

I haven’t been able to get more than 3-5 hours of sleep lately which has been a disaster for my body as I’m working really long hours & recovering from an illness. I take magnesium in the evening and used to take melatonin but i’ve phased that out recently (haven’t noticed a difference when i’m on it/off it). I try to have a “routine” that I can adhere to that makes my sleep more restful/easier but next to nothing has worked to improve my sleep quality. I’m kinda desperate for any advice I can get. TIA!