Mommy Brain

Is there actually any kind of medical evidence to backup what many of us call "Mommy Brain"? There is a book called "Mommy Brain" that claims having children make us smarter but I'm going to disagree with the author, at least for now. Ever since I became pregnant with Madison nearly 5 years ago I have not been the same. I used to think I had a decent memory and was somewhat on top of things but I have been so absent minded and spacey since having kids and it's driving me crazy. Kennedy is a year old now and I still feel every bit as spacey as before. At what point does this stop? Is it because we are constantly thinking about and ultimately responsible for three (in my case) human beings instead of one? Is it because I am still not getting a full nights rest? Is it because I don't have a job and interact with adults on a professional level on a regular basis? What is it and when will it go away? If any of you have come out the other end of this mommy brain phenomenon please post a comment and tell me about it. For now I will just continue to go about my days half conscious and hope I don't do anything too stupid : )