The steady creep of less sleep

Tweens and teens report getting less and less sleep with each passing year. The disturbing trend comes from data collected over the past 20 years from U.S. students.

As of 2012, more than half of the surveyed kids age 15 or older reported sleeping less than seven hours a night. That is two to three hours less sleep than doctors and others recommend. Sleep is essential, especially for young kids and teens. Too little sleep leads to poor health and poor performance in school. It also increases the risk of accidents.

The new study found consistent decreases in sleep between 1991 and 2012. The largest drops happened in the late 1990s and early 2000s. Details appeared online February 16 in the journal Pediatrics.

The study crunched data that were collected as part of a program called “Monitoring the Future.” Each year, this survey asks some 50,000 U.S. students a variety of questions about their behaviors. One of them: “How often do you get at least seven hours of sleep?” Another asks: “How often do you get less sleep than you should?”

“Overall, across 20 years and all age groups, 12 to 19, there has been a downward shift in the proportion of adolescents getting seven or more hours of sleep,” says Katherine Keyes. A co-author of the study, she works at Columbia University in New York City. As an epidemiologist, she studies the factors that can influence the health of certain populations, including teens.

Girls were less likely than boys to report getting at least seven hours of sleep, the researchers found. Students who lived in urban areas, belonged to minority groups or whose families were poor also were less likely to report getting at least that much sleep.

The biggest decrease in sleep was among 15-year-olds. Fewer than half of those surveyed in 2012 reported sleeping seven or more hours a night. That represents nearly a 20 percent decrease in nightly sleep for that age group since 1991.

Teens don’t recognize the problem

Also worrisome was the poor understanding by many teens of what is ”enough” sleep. Students from both minority groups and low-income families were less likely to get seven or more hours of sleep per night. These same students also were likely to report that they felt they were regularly getting enough sleep, the study found.

“A lot of teen-agers just don’t know what an adequate amount of sleep is. They get four hours and think they are just fine,” says Keyes. She adds that one message of the study is that kids need to learn the importance of getting a proper night’s rest.

The researchers are unsure why kids are sleeping less. Many people have blamed the rise of social media and increases in screen time. However, the steepest drops in sleep occurred in the years before Facebook and other social media sites became hugely popular.

More likely, a combination of reasons is to blame, says Daniel Glaze. He is medical director of The Children’s Sleep Center at Texas Children’s Hospital in Houston. He singles out demands put on teens by early school start times, sports, jobs —and yes, socializing. Obesity also may play some role. Obesity disrupts sleep — and teen obesity rates have risen as the length of a night’s sleep has declined.

“Clearly there are many factors we could improve and, hopefully, improve the amount of sleep,” says Glaze, who was not connected with the study.

But just educating teens to sleep more may not be enough to change their sleep behavior, report the authors of a second study. Educating local teens about the importance of sleep raised their awareness, researchers at The Chinese University of Hong Kong found. The bad news: It had no effect on how much the students actually slept. These data for Chinese youth also appeared online February 16 in Pediatrics.

Studies like these suggest that getting teens to sleep more will require tackling the root causes, Glaze says. The first study suggests places to look, he notes. For example, girls report getting less sleep than boys. He says it’s now important to ask: “What are those teen-age girls doing? Look at the factors related to specific groups.” Then, he says, it’s important to “not only educate, but address those factors.”

Keyes and her fellow researchers also found individual teens get less sleep as they grow up. The finding is significant. As of 2012, about two-thirds of 12-year-olds reported sleeping seven or more hours a night. That same year, only about one-third of 18-year-olds reported getting that much shuteye.

Power Words

(for more about Power Words, click here)

behavior  The way a person or other organism acts towards others, or conducts itself.

data  Facts and statistics collected together for analysis but not necessarily organized in a way that give them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

epidemiologist  Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.

factor    Something that plays a role in a particular condition or event; a contributor.

media      (in the social sciences) A term for the ways information is delivered and shared within a society. It encompasses not only the traditional media — newspapers, magazines, radio and television — but also Internet- and smartphone-based outlets, such as blogs, Twitter, Facebook and more. The newer, digital media are sometimes referred to as social media.

shuteye  Slang for sleep

survey  (in statistics) A questionnaire that samples the opinions, practices (such as dining or sleeping habits), knowledge or skills of a broad range of people. Researchers select the number and types of people questioned in hopes that the answers these individuals give will be representative of others who are their age, belong to the same ethnic group or live in the same region.