Help! Am i alone?

Lisa
34+3 And i just had to do something i usually refuse to do- phone in sick to work. I have had 1 hours sleep all night and i just dont feel safe making a 2 hour round trip to work and teaching a class of 5 year olds all day :( i feel so lame- i even gave the excuse that i hadnt slept because i didnt want them to worry about me. 
Is anyone else having similar issues? It isnt that im even uncompfy, its my mind racing and anything and everything, i just couldnt switch it off. What do you do when this happens to you? I was planning on working up until the end of june (due 13th july) but if this keeps hapening im going to have to finish earlier as i cant keep ringing in letting people down everytime i have an awful nights sleep. Im still 5 half weeks away it seems too early to start my leave- i want as much time off AFTER as i can :( 
Any tips other than a relaxing bedtime routine as i do that anyway? Please help xx