KS - Speaking as someone who has been through it I think the pressure you are putting on yourself to go sub-4 is most likely contributing to the loss of running mojo.
I ended up running sub-4 the first time using the least scientific or measured approach in the history of running. At the start of training for Paris 2012 my times were awful. I was getting frustrated and every step felt like a chore. I took the advise of the good people of the thread to start running and ignore the watch, just try and run for fun. I basically ran every training run from mid-January to race day using my Garmin as a stop watch. I went out and other than my LSR I ran every session as hard as I could. It was amazing that the second I no longer looked at my pace that my times started to tumble.
To this day in races I don't check my watch. Every PB I've ran has been run off instinct rather than using any measurements of time/pace/HR.
Eggy:I would say it definitely affected my run.In training I get to around 15 miles before I start feeling tired,yet after tapering I was tired pretty much from the off
I meant in terms of trying to relax your mind. It's normal to get pre-race gitters, but you have to tell yourself that you've done the work and the next day will be what it will be.
I'm normally fairly laid back the day before the race. Up early for a short run, stay off my feet as much as possible. Unlike RR I don't avoid caffeine, but I don't suffer any sleep issues due to it anyway. early dinner and an early night.
I'm a heavy sleeper naturally, so it's rare I have disturbed sleep, I tend to fall asleep ok, but on marathon night I do tend to wake up a few times, which is something I never do any other night.
It sounds to me like your are getting worked up and stressed. I think you need to find something that will take your mind off the race, actively avoid thinking about it while trying to get to sleep.
I always get some sleep the night before, but it's never the best. I try and have a few early nights in the week leading up to the race. I certainly find I run better when I've been sleeping well.
In terms of trying to sleep it sounds like you're worrying too much about the race the next day. Mentally I think you need to need to try and tell yourself you've done the training and the next day will be what ever it is. Nothing that you do at that point is going to change that, The work has been done over the months of training. That and if possible try and think of anything else but the race.