Dog Tired

I am not tired, but when I am tired this is how I feel:

I am dog-tired,
I need to sleep!
I am dog-tired,
I am seeing dancing sheep!
I am dog-tired,
I must finish my things!
I am dog-tired,
I will hear my clock as it pings!
I am dog-tired,
I need the rest!
I am dog-tired,
I must prepare for tomorrow's quest!
I am dog-tired,
Are you dog-tired?