When US student Olivia Priedeman, 17, woke up one morning, she thought she had had a dream about making plans with a friend.

But it wasn’t a dream. Her phone showed that during the night, Priedeman had read a text message from her friend. She did it while she was fast asleep.

Reading and sending text messages while asleep - called “sleep texting” - is an unusual sleep behavior, similar to sleepwalking. It’s also a growing concern among doctors: young people can’t live without their cell phones.

One in three teenagers sends more than 100 text messages a day, according to the Pew Internet & American Life Project. And at least four out of five teenagers said they sleep with their phones on or near their bed.

Elizabeth Dowdell, a professor at Villanova University in Pennsylvania, has studied sleeping texting. She said that having a phone nearby all night is a big part of the problem.

Andrew Stiehm, a sleep medicine expert with Allina Health in Minnesota, agrees. It’s possible for the part of the brain that controls motor skills to wake up, while the part of the brain that controls memory and judgment may be still asleep. That’s why some people can perform basic movements-such as walking, talking, texting or even driving-while they’re sleeping. Some of Dowdell’s students said that they’re disturbed by their nighttime texting behavior. But because sleep texting is unconscious, it’s a difficult habit to break. Dowdell said she knew some students who wore socks on their hands to keep themselves from texting,

Marjorie Hogan, a doctor at Hennepin County Medical Center in Minneapolis, Minnesota, suggests keeping all electronic devices (电子设备) outside the bedroom at certain times.

The Internet is becoming important in our life. How much do you know about it? The following questions and their answers will help you to know more about the Internet.

The Internet is a large, world-wide collection (聚集) of computer networks. A network is a small group of computers put together. The Internet is many different kinds of networks from all over the world. These networks are called the Internet. If you have learned to use the Internet, you can have a lot of interest on the World Wide Web.

The World Wide Web has been the most popular development of the Internet. It is like a big electronic book with millions of pages. These pages are called homepages. You can find information about almost anything in the world on these pages. For example, you can use the Internet instead of a library to find information for your homework. You can also find information about your favourite sport or film star, talk to your friends or even do some shopping on the pages. Most pages have words, pictures and even sound or music.

Electronic mail (e-mail) is a way of sending messages to other people. It’s much quicker and cheaper than sending a letter. If you want to use e-mail, you must have an e-mail address. This address must have letters and dots and an @ (means “at”). For example: Lily @ Yahoo.com. Write a message, type a person’s e-mail address, and then send the message across the Internet. People don’t need to use stamps, envelopes or go to the post office because of the invention of the Internet. Quick, easy and interesting — that’s the Internet.