I waited all my life for someone to think I'm famous :)
But seriously - as part of my job I get hundreds of emails every day that I need to review or respond to. It's a reasonable usage scenario I think.
1) mute your iPad,
2) Don't sleep in the same room as your iPad.
In addition to more complicated ones being offered elsewhere in this thread.
I was just posting to point out that it isn't necessarily a design flaw just because it doesn't fit your use case as, to the contrary, I would be very upset if my device didn't notify me of something just because it was sleeping.