Two hundred years ago the essayist Leigh Hunt wrote a piece that was destined to become famous, called "On Getting Up on Cold Mornings," about the extreme difficulty of persuading oneself to get out of bed in winter. This appealed strongly to about half the population. Then as now the world was divided into Morning People and Night People. Morning People are energetic, immature and rash. They get up in what is more or less the middle of the night and rush cheerfully off to work in the freezing dawn. Night People are more mature, more thoughtful, and less impulsive.