Sleep alludes me...

So I knew going into our life here in Pittsburgh that life would be tough for awhile. We were starting over, and had to scrape the bottom of the barrel before we could start climbing back up. Well we scraped that bottom, a few times. I had hoped that Fionn's stint in the N ICU was the last that our family would be super stressed out...We're all be tested again though, and could use some prayer. Nothing is wrong between Greg and I, our relationship is still as great as it has ever been. It's our life as a family that is being stretched thin and we love just being together so it's hard on all of us.
Greg decided to work third shift starting last week, and I know it's what he has to do for now while working on his doctorate, but that's going to take another three years! It's only been one week and we are stretched thin already. Sunday's are his only day off, but he works overnight on Saturday's so he's still going to need to sleep at some point. Poor Maggie barely sees daddy now that she's in school and doesn't get home until almost 2:45pm and Greg leaves for work around 6pm. She's already at school most mornings when he gets home. Even Saturday mornings she gets up and is out the door by 8:45am for gymnastics and dance, so she's on the go. Tonight she was pretty upset at bedtime and told me that she just "missed daddy"
I know how she feels...i don't know what it is, if it's where we live, or what the problem is, but I cannot sleep when Greg is gone at night. I will not take anything to help me sleep because I need to hear Fionn (or Maggie) if they wake up and even if i do doze off i have horrible dreams and never fall into a deep sleep. Ever since the night when those boys cut through our yard this spring late at night and banged on our house I've been scared of where our house is located. Our street itself is safe(same street we've lived on since we moved to the 'burgh)and we love our neighbors, but something just leaves me unsettled. I can be home alone all day long with the kids and never have an ounce of fear, but as soon as night falls, something in me changes. I have not one ounce of fear when Greg is here, and have never really had a serious fear before, so this is all new to me. All I know is that i cannot possibly survive for the next three years with the amount of sleep that I am getting. If I can string together FOUR hours I consider it a good night...So I'm asking for prayer. You are all amazing, and I know this seems so trivial compared to what others are facing, but no matter what I try to think about, or pray about, nothing eases these fears. My biggest fears is that something would happen while I was sleeping, and I wouldn't be able to protect Fionn and Maggie and keep them safe.
I know that most parents fear not being able to protect their children, i just don't think it's something that stays in the front of their mind almost daily. I am so tired, it's after 3am again tonight and this is still early for me. The kids will be up at the latest by 7, and I have to be up with them all day again. At this rate, I'm going to be a bear tomorrow.
If anyone has any suggestions I would love to hear them. Just being able to sleep would help make things a little easier, at least then I can enjoy what little time I do get with him!
Thanks