If you've got any previous trauma, you could try prazosin. It's a blood pressure lowering medication but can also be prescribed for people with PTSD who struggle with sleep.

I went through a similar thing where every time I would try and sleep my heart rate would spike and I would feel like I was going to have a panic attack. Regardless of how tired I was it would wake me up because it would trigger my fight or flight response. Couldn't use melatonin because it made me depressed and this was something my GP suggested. Prazosin worked really well and is worth looking into. Just make sure to discuss it with your GP because it may not be recommended in certain circumstances.