Karen, grown up in a very traditional family in the western United States, maintained high moral (道德的) standards throughout her youth. In 1984, at the age of 23, she married Bill. They were blessed with two children, a boy and a girl.

By 1991 their love had deepened, and they were happy. Later that year, Bill developed a white spot on his tongue. He visited a doctor.

One day shortly after that, Bill called Karen to sit beside him. He said with tears in his eyes that he loved her and wanted to live forever with her. The doctor suspected that he had been infected with HIV, the virus that leads to AIDS.

The family was tested, Bill and Karen’s results were positive. Bill had become infected before he met Karen then he passed the virus on to Karen. The children’s results were negative. Within three years. Bill was dead, “I don’t know how to express what it is like to watch the once handsome man you love and intend to live with forever dying slowly. I cried many nights. He died three months short of ten years of our marriage,” says Karen. Though a doctor told Karen that she would soon follow her husband into death, she is still alive. The infection has progressed to the early stages of AIDS.

Karen is just one of about 30 million people now living with HIV/AIDS, a figure larger than the combined populations of Australia, Ireland and Paraguay. According to one UN report, Africa has 21 million of these victims. By the turn of the century that number could reach 40 million and the disease will bring on the greatest disaster in human history. Of the world’s sexually active adults aged 15 to 49. 1 in 100 has already been infected with HIV. Of these, only 1 in 10 realizes that he or she is infected. In some parts of Africa, 25 percent of the adults are infected.

Since the beginning of the spread of AIDS in1981, about 11.7 million people have died of it. It is roughly calculated that in 1997 alone, about 2.3 million people died of it. Nevertheless, there are fresh reasons for optimism in the battle against AIDS. During the past few years, there has been a drop in new AIDS cases in wealthy nations. In addition, promising drugs hold out hope of better health and longer life.

Sleep in Different Cultures

It is apparent that there are significant differences in sleep patterns in different parts of the world, and that sleep patterns have also changed over time. Traditions, cultural values, local conditions and environments all influence sleep patterns.

One major source of these differences is the widespread use of artificial(人造的) light, which has led to changes in the sleep patterns in the industrialized world. It is thought that today we sleep several hours less than before industrialization. Artificial light has encouraged people to go to bed later and to sleep the whole night through (Monophasic Sleep), rather than the more broken up and flexible sleep patterns (Biphasic Sleep). During the long nights of the winter months, our ancestors used to break sleep up into two or more parts, separated by an hour or two of quiet restfulness.

Even within the developed world, there are still significant differences in sleep patterns. A study carried out in ten countries in 2002 showed some of these regional variations. For instance, the results of sleeping time at night from individual countries varied from 6 hours 53 minutes in Japan to 8 hours 24 minutes in Portugal. Over 42% of Brazilians took regular afternoon naps (short sleeps), compared to only 12% of Japanese people.

A daytime nap is a common habit among adults in many countries. Spain, in particular, has raised the nap almost to the level of an art form. The experience of Japan is a clear example of the way a culture change can affect sleep patterns. In the 1950s, Japan was keen to rebuild. Japanese workers were encouraged to wake early and finish late as well. The work-place nap was encouraged as a way for a worker to increase productivity, even though in fact it probably degraded the quality of night-time sleep even more. Today, sleep is perhaps more undervalued in Japan than anywhere else.

It is clear, then, that there are cultural and historical differences in our sleep patterns. Yet the one thing that stays the same across all cultures is the one truth about sleeping: We all do it!