Dangers of Editing when Tired

I've been plugging away on my book.  I had to take a break because after the last post, we had two full weeks of sickness at our house.  I wasn't getting any sleep to begin with, so writing had to go on the back burner.  But I'm making progress again!

Last night I sat down to write, and as usual, read through the changes I'd made the night before.  Whoah, Nellie.  Someone was tired on Friday!  I found all sorts of weird problems in the 1/2 chapter I'd revised.  A few examples:

• I've been checking for passive verbs, but sometimes I don't get the sentence completely fixed.  "She was carrying the books" is supposed to become "She carried the books", but Friday night, the sentence looked more like "She carrying the books."  Which would be fine if I was writing in the voice of a four-year old, but I'm not, so... not so great.
• I've been deleting entire sentences when they aren't important.  But Friday night, I apparently wasn't getting the whole sentence.  So I would have random words like "She" or "because" or "monkeys" just floating around in the middle of a paragraph.

There's not much of a point to this story- I just thought it was funny!  And a little alarming.  I hope the rest of the book isn't like this.  Maybe I really do need more sleep!