Rise above it and leave it all behind. The darkies are really really desperate and will do anything to hold on and can't. Just say to yourself "this is not mine and I leave it all behind now". Think!
Yes, I've had similar experiences.
Try to change what you are doing every day at that time. It could be as simple as going out for coffee, taking a walk, or anything that distracts you from the bad vibes.
I've found spiritual healers helpful in getting rid of old memories and bad energy. But changing your pattern can help, too. At 4:00, instead of waiting for those nasty vibes, pick up a book on how to attract positive energy. I suspect it might be something in your past, something that happened to you when you were really young and your mind has suppressed it but your body remembers it.