Trouble Sleeping...

Last night I slept in a preschool classroom on a sleeping mat in a sleeping bag.  I went to sleep just before midnight and was up at 6 am.   Lest you think I am staking out the arena of small children (I could just stay home for that one.) I was an "adult" (it said so on the sheet taped to the classroom door) for my daughter's lock-in.  Lest you think I am crazy I would like to remind you that no children who normally wake me every two hours were permitted to come and I turned off my cell phone.  I actually got more consecutive hours of sleep there than I would have had I stayed home.
So, tonight I am lying in bed at 9pm and find that I am not able to go to sleep.  WHAT???  I have yet to figure out if this inability to fall asleep as quickly as I use to is because of pregnancy or anti-depressant medication or just a general increase is the hours of sleep I get over the course of a week.
Yes, pregnant.  You read that correctly.  Baby #6 is due 11 August.  I don't care what you see on my OB record that says 6 August, I am not due that day.  Now, baby may be BORN that day but then again, maybe not.  Why do doctors refuse to listen to a mother when she says, "My husband was out-of-town during the time you are saying I conceived."??  I am not sure how this whole thing happens...just ask my neighbors...but I am fairly certain that it isn't long distance.  Mind you, this is only the sixth time around so we haven't quite figured the whole system out yet.  We are fairly certain it doesn't involve cold weather, TV or the water.
But I digress...
The anti-depressant has been wonderful.  I have been anti-drug forever and am so glad that I didn't fight it this time.  I am thinking of taking it after the baby is born (I am weaning off of it now b/c of pregnancy) just for GP.  (Kidding...sort of.)  Don't think decreased ability to fall asleep is due to this drug.
Since the terror of the house has been sleeping through the night for the past month (he will be three at the beginning of March...yes that is a LONG time to have a child NOT sleep through the night) I have "only" been up at 2am and 5 am with the 16 month old.  Add that to the daily naps that first trimester demands and my total number hours of sleep has increased...I think.  It doesn't feel like it some days but the numbers don't lie.
I am now going to attempt sleep, again.  This time without the preschool classroom and sleeping bag but with the 16 mo. old.  We'll see how it goes. I may have to ask if I can use the classroom more often.