Rest & recovery is a key part to becoming a better runner and sleep plays a huge role in this. If you are working to a training plan, why not look to introduce a sleep routine as well.
Create a night time routine that will help you fall asleep better. There is loads of information out there on sleep. Making small changes such as leaving your phone out of the bedroom can make a big difference.
Try to wake up at the same time each day and don’t panic if you have a broken night’s sleep on race day. You can still run a PB and as long as it’s not an Ultra, you can always have a nap in the afternoon.