Before I continue, I would encourage you to see your GP and get some bloodwork done, to make sure there's no medical reason why you're having trouble sleeping. Otherwise, this advice would sound pretty silly.
I definitely feel like I am qualified to talk about this, because I had a rocky night's sleep last night, and I am just about to fall asleep again. I also work nights. I remember a few years ago, when they started some very late shifts, I was paranoid about sleeping in and missing work, so I would stay awake. Then, I would finish work in the early morning, but I didn't want to lose my entire day, so I wouldn't sleep during the day either. I would get up to two days without sleep, and it was having such an effect on me that I was having memory issues, and basically felt like I had been hit by a truck every day. Eventually, I decided that napping was worth the risk of sleeping in.
The two biggest things with sleep are routine and association. Try to set yourself up so that you go to bed at roughly the same time every night, and do the same things before bed.
A cup of chamomile tea definitely helps. I have a cup of Twinings Asha, which is a blend of chamomile, peppermint, spearmint and lemon peel. The important thing is, though, to make a habit of making a cup of tea an hour or so before bed, to tell your brain that it's time to sleep. Similarly, taking a shower, brushing your teeth, things you normally do before bed, make a habit of doing them at the same time each night. Make it a process, or a ritual. That way, your brain associates those activities with sleep.
As far as distractions go, try not to work or surf the web or do anything like that in bed during the day. That is totally hypocritical of me, because I am writing this from my bed! Really, though, it's important to "separate your areas", so your brain associates your bedroom with sleep. Maybe it's worth hiding your phone before bed. Experts recommend switching off an hour before bed. Ideally, even longer than that. At that point, put your phone somewhere where it's not worth the effort of trying to retrieve it until morning comes.
The most important thing here is to remember that it's not going to be perfect. It takes at least three weeks to establish new habits. Be patient with yourself. I hope it improves for you, though.
Good luck.
