CHICAGO — A relaxing summer evening for 18-year-old Ross Nikides last week went like this:

He and five friends brought laptops to another friend's house to play World of Warcraft and other Internet games against each other.

Around 4:15 a.m., one of the guys craved a milkshake, so they piled into two cars and drove around Carol Stream, Ill., in search of an ice cream shop still open.

An hour later, they were back at the friend's house, slurping down their drinks while checking Facebook and playing X-Box until they finally fell asleep — cell phones by their sides — around 6:15 a.m.

"It was a good bonding experience with friends," said Nikides, who woke up 7 hours later and had enough energy to go for a run.

Nikides and other teens are averaging 6.5 to 7.5 hours of sleep a night, well below the 9 hours recommended in a newsletter this month by the Archives of Pediatrics & Adolescent Medicine.

Hanging out with friends and staying up late may not be different from what some teens did 30 years ago, but new research suggests technological distractions that teens have access to today cut into the quality of their much-needed rest.

A study published in the journal Pediatrics last year showed that teens kept up their activities late into the night. After 9 p.m.,
82 percent of the high-school students surveyed were watching TV, 55 percent were using a computer online and 44 percent were talking on the phone — with another 34 percent sending and receiving text messages. Of that group, only 20.6 percent got the 8 to
10 hours of sleep recommended.

In a study of teens in Belgium in 2007,
40 percent of the 16-year-olds surveyed reported they were woken up at least once a month by a text message, which correlated with higher levels of daytime sleepiness.

Yet despite years of warnings about the risks of insufficient sleep — including poor school performance, obesity and, as presented in June at an annual meeting of sleep researchers, links to depression — teens and their parents say adolescent exhaustion remains a fact of life.

And the best they can do is to balance their teens' need for sleep with their need to keep up with today's technology.

"Teens don't value sleep because there's too many things going on to distract them," Nikides said.

Scientists studying teen sleep deprivation have several theories about why exposure to technology cuts into rest, and the research continues, said Amy Wolfson, a sleep researcher and director at the National Sleep Foundation.

Some suggest that the media simply take the place of sleep and exercise time. Others point to the arousing content of TV, video games and music as a sleep deterrent. Increased caffeine use could be a factor. And a more controversial hypothesis is that bright lights from the screens trick teens' bodies into delaying the secretion of melatonin, a hormone that helps trigger sleep at night, Wolfson said.

Still others believe it is the combined use of multiple technological devices at once that keeps teens alert past bedtime.

One night last week, Ryan Cassidy, an 18-year-old recent high school graduate, began playing Xbox at 10:30 p.m., using two-minute breaks within the game to play another game on his cell phone. After two hours, he moved on to his laptop, on which he watched a TV program and checked his Facebook page during commercials.

Cassidy eventually decided to go to sleep at 2 a.m.

"I'll wake up a little tired, and I know it's because I stayed up late playing games or something, but to me, it's almost worth it," the Geneva, Ill., teen said.

The issue has become a hot topic among sleep researchers, who have long argued that teens are already sleep deprived because early school start times don't take into account the way adolescent hormones change teens' natural sleep cycles and make it harder for them to go to bed early.

Teens need adequate deep and REM sleep to rebuild long-term memory for learning, focus attention for driving and maintain health and fight obesity, said Dr. Matthew Edlund, director of the Center for Circadian Medicine and author of The Power of Rest.

"From a public health standpoint, I look at this and I am scared stiff," Edlund said. "They're so connected to their machines that they're treating themselves as though they don't need any rest."