Thanks Mark, I find that watching TV or being on my computer/iPad at night makes it worse - seems to stimulate my nervous system more.
I am a yoga teacher so have breathing and meditation exercises that calm my mind. I don't lie there thinking, as I'm quite good at noticing when my mind is running amuck with thoughts, and can slow it down, or stop it alltogether quite easily.

Instead it is a sensation of just being wide awake and energized instead of feeling tired, as one usually does at the end of the day. There is a sensation almost of electricity crackling in my head at night. My body usually feels quite energized as well. Some nights I listen to really calming music and will lie there for a few hours in the dark just listening, not even thinking much, hoping to drift off. But that doesn't happen. The exhaustion usually comes in the morning from about sunrise.
My sister has suggested just staying up all night and then not sleeping in the day/morning, untill I'm so exhausted I can't help but fall asleep the next night. I tried that yesterday and it was still difficult getting to sleep last night. I think I will keep trying that though.

I'm really glad this forum is here, just to share, so that I don't feel crazy!