I know I need more sleep
when halfway to work I realize my daughter is still in the car and not dropped of at school. (Was about an hour late at work that time)
when I try to microwave my soup in the fridge or put the mixer in the oven.
when I'm suddenly at work and don't really remember how I got there.
when I eat my cereal with cola instead of milk (that was really yuk)
I'm sure there will be more, when I'm not to tired to think of more.