Signs of Sleep Deprivation

#1: Loss of motor skills

It's embarrassing how badly the lack of sleep affects one's ability to do seemingly simple things like walking. I would not be surprised if people have started to question my ability to care for an infant if I keep walking myself into walls, or if Michael should be trusted with flight hardware if he keeps missing steps on the stairs. Really... those walls and steps can be tricky S.O.Bs.

#2: Memory loss

Just this morning would be an excellent example of this -
Niffer - What are our conclusions on how last night went?
Michael - Well she slept for 2 hour stretches, right?
Niffer - No, she slept for 4 hours and then 2 hour stretches.
Michael - No, she went to bed at 7:30 and woke up at 9:30.
Niffer - No, that was the night before.
Michael - Remember? You said "I can't believe it's only 9:30, I slept so hard."
Niffer - Yes, but that was the night before, when we didn't watch anything before going to bed.
Michael - We watched something last night?
Niffer - Yes, the remainder of the movie.
Michael - Didn't we do that two nights ago?
Niffer - Hmmm... I don't know.
Michael - Maybe we should start keeping a notebook of her sleeping habits.
Niffer - You're a smart man.

#3: Flawed logic

A good example from two nights ago (I think):
Michael - We humans got this whole thing backwards.
Niffer - What do you mean?
Michael - Like that video of the colt just popping out and being able to run and eat right from the start. It's too bad we have to be born before we can take care of ourselves because of our large brains.
Niffer - Yeah, animals did it right.
Michael - Well I guess puppies are born without their sight.
Niffer - Yeah but that makes sense because they have better vision.
Michael - So they're born earlier because of their huge eyes?
Niffer - Exactly.
Michael - What kind of freakish huge-eyed dogs have you seen lately?
Niffer - Uh... Good point.