Model
A glance at four indicators of economic and social conditions in four countries, Canada, Japan, Peru and Zaire, in 1994 reflects the great differences that exist between wealthier and poorer nations.

The table shows that Japan and Canada had annual incomes of $15 760 and $11 100 per person, respectively. These figures were overwhelmingly greater than the corresponding figures of $160 in Peru and $130 in Zaire.

Health indicators, too, reflected overall levels of affluence in the four nations. Life expectancy at birth, for example, was higher among the more economically developed countries. Japan reported the highest life expectancy, 78. This was followed by Canada, 76; Peru, 51; and Zaire, 47; This suggests that richer societies are able to put more money into health care than poorer ones.

The amount of calories consumed daily per person roughly followed the same ranking. Canadians each consumed some 3 326 calories per day while the Japanese took 2846 calories. The corresponding figures for Peru and Zaire were 1927 and 1749, respectively.

Literacy rates among adults, too, were higher in wealthier countries, no doubt a reflection of ability to invest in education. Canada and Japan both reported literacy rates of 99%, while Peru claimed 68%. Zaire, the least economically developed of the four countries, had a literacy rate of 34%.

The data appear to confirm the often cited link between national wealth and health and education standards.
Model
Differences in sleep patterns appear to reflect differences in individuals' occupations.

A Canadian study has pointed out, for example, that students typically sleep for a consecutive 8-hour period each night, from 11 p.m. to 7 a.m. This may be because the central activity in their lives, study, takes place in normal daylight hours. Similarly, business executives sleep consecutive hours, but perhaps because their jobs are especially busy and stressful they sleep for 6 hours on average, getting up around 5 a.m..

By contrast, truck drivers, probably because of their need to keep their trucks on the road over long periods, tend to sleep in two 3-hour blocks: one between 7 and 10 a.m. and another from 4 to 7 p.m. Another occupation associated with broken sleep schedules is that of doctors. They tend to retire to bed around 1 a.m. and start their day at 7 a.m.., but may be woken up to deal with emergencies in the middle of the night. Finally, full-time mothers, especially those with young children, tend to sleep when their babies do. Typically, they will sleep from 10 p.m. and be awoken at 1 a.m. to comfort their babies for a couple of hours. They then go back to bed to wake at 6 a.m., but nap for two hours or so in the early afternoon.

Thus the influence on one's sleep pattern is worthy of consideration when choosing an occupation.