Will Sleep Ever Return?

This post is going to be a bit of a rant and a moan Im afraid.
I am just so tired! Since having the twins 17 months ago sleep, as we knew it, has gone out of the window. Yes, we do get more than we did, but to get a block of 8 hours sleep would be such a luxury. At the moment I am managing to get a maximum of 6 hours, not always in a block and that's on a good night, which I can manage on for so long but then I have a day like today and just feel shattered. During the week I have found the more I keep busy the less tired I feel. I know it sounds crackers but it does actually work! Im probably feeling like this because I am sat at the pool while Joseph has his swimming lesson, its warm and I've stopped. I am just feeling so drained and feel like I could sleep for a day. I don't remember feeling so sleep deprived when Joseph was a baby/toddler and please don't get me wrong the twins are good sleepers I just wish that they would both have a good nights sleep at the same time instead of taking it in turns to be up and down. However I do feel that some of the blame does lay with me, as I get up as soon as I hear either of them. I am not a fan of self soothing and could never leave them to cry but I am also aware that we have 3 children and I don't want them waking each other up or hubby up when he has to go to work. So I'd rather have disturbed sleep than everyone else being up. The nights wouldn't be so bad if they slept in but they are up at the crack of dawn, which at the moment tends to be about 5am!
I know it will get better and that Im obviously just feeling it today, I just can't wait until sleep returns!