Personality: As someone who has personally experienced this debilitating loss of sleep, I can safely say that on the days when I lose a lot of sleep, I am a very grumpy and unapproachable individual.

Twice after our meetings he has sent me text messages, apologising for sounding grumpy.

Do your kids go off to school feeling calm and confident? Or are they upset and grumpy?

We are all equipped to deal with a certain level of stress, but at a certain point our bodies throw up the white flag and we're left feeling exhausted and short-tempered.

My friend, however, somehow always ran into grumpy people, encountered conflicts, and wound up in fights.