【推荐1】Birds do it. People do it. Owls do it in the daytime. Even Caenorhabditis elegans, a primitive roundworm made up of a few thousand cells, does something that looks an awful lot like it. Sleep is an ancient, universal experience.

But partly because it is so commonplace, for a long time sleep was a subject that scientists had not woken up to. It is only in the past half-century or so that it has attracted the attention of dedicated researchers. A new book from Kenneth Miller, a science journalist, sets out to elaborate the field’s short but fascinating history. The book is organized around the life and hard work of a scientist named Nathaniel Kleitman who set up a pioneering sleep-research programme at the University of Chicago.

The early pages of the book, before there is much in the way of established science to describe, are the weakest. A good deal of time is spent on biographical details and pen portraits of the world through which Kleitman moved. But the story soon picks up. It ranges from the discovery of rapid-eye-movement (REM) sleep and circadian rhythms — the biological clocks that govern humanity’s days — to the effects of sleep deprivation (which can be fatal, at least in lab animals). It also probes the purpose, if any, of dreams.

Underlying it all is a sense of psychology's slow maturing as a science. New technologies such as electroencephalographs, which monitor electrical activity in the brain, have offered practitioners the ability to study brains directly, rather than trying to infer what they are doing from the behaviour of their owners.

Discoveries often lead to new questions in turn. That is why neat, tidy endings are hard to achieve in science books; this one is no difference. Despite all the progress of the past 50 years, scientists are still unsure what sleep is for. For anyone curious about asking the right questions, however, Mr. Miller’s book is a good place to start.

【推荐1】Summer is the best season to experience the world's beauty. Here are some of the best destinations that you can't afford to miss in the world.

Maui , Hawaii

Maui is a volcanic island. If you love snorkelling, you must see the rainbow of coral and tropical fishes. Stay the day in the park and witness its wonderful sunsets. The island consists of a few micro-climates and weather varies drastically depending on where you are. The tropical weather can even vary day-to-day with extremes such as sunshine and thunderstorms, so pack accordingly.

Corsica t France

This small island, also called the “isle of beauty”, displays astonishing natural landscapes. Shocking cliffs drop sharply down to clear waters which elsewhere are fringed（带边饰的）with sandy beaches. Plan at least a week in Corsica to discover its secrets!

Bora Bora, French Polynesia

Bora Bora is popular with tourists for its luxurious resorts（度假胜地）. One of the best hotels is the five star Four Seasons hotel. Surrounded by beaches of white sand and blue water protected by a coral reef, it is a really nice place to snorkel and dive. The most impressive sight of the island is in the center of Mount Otemanu where there is a sleeping volcano.

Saint John Island, Caribbean

Life moves at a slower pace on Saint John Island. The National Park covers more than half of the island. With countless bird, dolphin and turtle species to spot, it's no surprise that this is a destination that draws nature lovers. Peace and quietness are abundant, making this an island where relaxation is always on the agenda（议题）.

【推荐3】Fans, with different materials and shapes, are not only a means to cool down in the hot days but also a part of the culture for the Chinese. Here are some of the interesting cultural meanings for the fans in China.

Feather fans

It is the earliest form of fans. Its most famous user is Zhuge Liang of the Three Kingdoms period, who was the best adviser to a king. He always carried a white feather fan around. Since then the feather fans have become a symbol of wisdom in the Chinese classic literature, traditional paintings. They even appear in today's TV series and films now and then.

Round fans

If feather fans were loved mostly by men, round fans were Chinese women's best friends. The round fans, originated in the West Han Dynasty, were usually made of bamboo frames of round or oval shapes, and white fine silk. Therefore, they could only be afforded by wealthy families back in those days. In Chinese culture, the round fans are closely linked with elegance (优雅) and beauty of women, as well as their happiness and sorrow.

Folding(折叠) fans

The folding fans are quite familiar to us. In fact, the folding fans originated in Japan, and were introduced to China in the Northern Song Dynasty. The popularity of the folding fans owed greatly to the Chinese scholars(文人), who loved to paint and write on the folding fans and turned them into art pieces.

Big leaf fans

The big leaf fans are a link to the traditional lifestyle. Many elderly Chinese can still remember those summer days, when neighbors sat together, waving their big leaf fans, drinking tea while telling the stories of their daily lives.