Just that! I've always had issues with sleep before big events (exams and interviews but also day trips I'm excited for, birthdays, other people's weddings etc.) I've tried over the counter sleeping aids with no effect, am always careful with sleep hygiene, avoid caffeine etc. I sleep ok most other times but have always had this problem. The anxiety is about not being able to sleep, rather than the event, which ironically then keeps me awake. I think having a routine of hot drinks, low caffeine, meditation, nytol etc. actually makes it worse as I'm even more focussed on whether I sleep!
Anyway, I'm getting married in now under one week and, whilst I'm not worried about the day or marriage itself, I'm so worried about not sleeping. This isn't helped by the fact that, normally if I'm struggling to sleep, I drop off around 4am. However, on this day, I have to be up at 5(!) to start the day (unfortunately this is due to vendors and is non-negotiable, I've tried very hard to push this later!).
I'm already feeling worried about not sleeping and having restless nights. I've convinced myself that I'll be exhausted and ruin the day, will have wasted lots of money etc (yes, I'm aware these thoughts are definitely not helping!). I've now decided to take a new approach and, instead of stressing about sleep the night before, accept I'll be resting, rather than sleeping, and will get through the day on adrenaline.
It would be really helpful to hear of positive stories of people who didn't sleep before their wedding / big event and were totally fine on the day.