Between their crazy schedules and upside-down circadian rhythms, teens always have been somewhat sleep-deprived. Now technology is making it worse.

       Teens are not just texting, instant-messaging and surfing Facebook all day; they're sleeping with their cell phones or laptops, too. Or rather, not sleeping. And doctors and parents, many of them raised in an era when phones were attached to walls, are concerned.

       "So many teens are having sleep issues, and parents aren't necessarily regulating the use of the electronic devices enough,'' says Margie Ryerson, a Walnut Creek, Calif., therapist who specializes in adolescent issues. "It's impossible to wind down and relax the body, the mind, the senses and be ready to fall asleep.''

       The texting doesn't stop, she says, even after Mom and Dad are snoring softly in their beds. One of Ryerson's clients discovered her 17-year-old daughter was sending more than 3,000 text messages a month, many in the wee hours.

       Of course, for every obsessive texter, there's a teen, "tween'' or college student who simply turns off the phone at bedtime. But even the averages are extraordinary. A 2009 Nielsen study on teens and media found a 566 percent jump in teen texting rates during the past two years. The average teen sent 435 texts a month in early 2007. Now it's 2,899 a month -- 97 a day.

       A Belgian study published last month found that late-night texting is affecting the sleep cycles of 44 percent of that country's 16-year-olds. Some 21 percent are waking up one to three times a month to answer a text message, according to the Leuven Study on Media and Adolescent Health; it's a weekly occurrence for 11 percent of the teens, and a nightly or every-other-night wake-up call for 12 percent.

       "We all know teens don't get enough sleep in general,'' says San Francisco youth culture expert Anastasia Goodstein. "As long as parents allow teens to have these devices in their bedrooms at night, teens will be tempted to use them. "Teens would socialize 24/7 if they could -- especially if it's with a girlfriend or boyfriend.''

       Ryerson calls it the CNN syndrome of teenhood -- round-the-clock reports on breaking news about everything from homework to wardrobe choices to Starbucks cravings.

       Norman Constantine worries that the stakes are higher than most parents realize. The director of the Oakland, Calif.-based Public Health Institute's Center for Research on Adolescent Health and Development says sleep deprivation is linked to memory and concentration problems, anxiety and depression, moodiness and hyperactivity.

       "Many people assume these problems arise directly from adolescence, which is not really true,'' he says. "The real issue is sleep deprivation. Late-night texting can certainly make the situation worse. But one has to ask: Are the teens texting because they can't sleep, or are they staying awake because they are texting? We really don't know.''

       Teens tend to see sleep-deprivation as a "victimless crime,'' says San Jose psychologist David Marcus. So what parents can do is help them understand cause and effect. Have them go one week doing what they're doing; then have them try getting some phone-free, undisturbed sleep for a week, and evaluate the differences. Ask, "How's your energy for sports, quizzes and classwork? Your ability to handle conflicts with your friends? How do you really want to treat yourself?''