10 things you didn't know about sleep

1. In 2004 Americans filled more than 35 million prescriptions for sleeping pills. The number of adults aged 20 to 44 taking pills to help them fall asleep has doubled in the last four years.
2. More than 100,000 car crashes in the United States each year result from drowsiness. Drivers talking on cell phones increase the rate by 6 percent, so don't call someone if you get tired.
3. In 2008 Volvo plans to unveil a system that will monitor a driver's eyes and head, along with the movement of the steering wheel. If a driver seems to be nodding off, interior lights will start to flash.
4. A six-year study of a million adults showed that people who get only six to seven hours of sleep a night have a lower death rate than those who get eight hours. Maybe it's those late nights watching QVC.
5. In 1964 17-year-old Randy Gardner stayed awake for 264 hours and 12 minutes, the world's record. He then slept for 15 hours—not a record, but not bad.
6. The idea that it is dangerous to wake a sleepwalker is a myth. Given the things sleepwalkers get up to do, like climbing roofs and fixing insanely large sandwiches, it is probably more risky not to wake them.
7. Whales and dolphins can fall half asleep. Their brain hemispheres alternate sleeping, so the animals can continue to surface and breathe.
8. Dreaming is connected to bursts of electrical activity that blow through the brain stem every 90 minutes during REM sleep. Over a lifetime, an average person spends more than six years dreaming, clocking more than 136,000 in all.
9. But nobody knows why we dream.
10. The fear of sleep is called somniphobia.