Night wandering

I'm like a ghost in my own house at night, the wonderful exhaustive sleep that saw me through the first few weeks after loosing Jack is well and truley gone.
I cant get to sleep, i try serveral times a night to get there but i cant. i go to bed, lie there with my brain going 100 miles an hour, thinking of lots of things, my beautiful boy, the day he was born, fantasising different outcomes, none of them leaving him at the hospital, another baby.
i get up, wander around, clean things, fold things, put things away, make a hot chocolate, have a smoke, try again. NOPE, up i get again and repeat the process.
eventually i get to sleep, then morning comes, the kids are hollering and i just dont want to get out of bed and could sleep all day. Why does this only hit me when its dark? i'm tired, beyond tired, i look like absolute shit because i'm so tired, but still i cant sleep.
Mum gave me some rescue remedy sleep stuff, will give that a go tonight