Later School Times Suggested by American Academy of Pediatrics

Dr. Judith Owens, director of sleep medicine at Children's National Medical Center in Washington has recently submitted a policy statement requesting that school districts delay starting times for morning classes.
Recent research has shown that adolescents who get enough sleep have a reduced risk of being overweight or suffering depression, are less likely to be involved in automobile accidents, and have better grades, higher standardized test scores and an overall better quality of life. Studies have shown that delaying early school start times is one key factor that can help adolescents get the sleep they need.

Many school districts are debating the change; the Long Beach, California, school board voted last year to delay the start of middle school until 9 a.m. But it’s a complex issue with school boards, educators and parents struggling to balance bus schedules, after-school activities and work schedules for older students. 

Nonetheless, Owens says biology should trump convenience. She notes that when teenagers go into puberty, there are changes in their circadian rhythm, the body's natural clock that regulates sleep and wake patterns. At the beginning of adolescence there is a natural delay in sleep and wake times, so that the average teenager doesn't fall asleep until around 11 pm.
 However, they also need between eight and nine hours of sleep per night so they are biologically programmed to wake at around 8am, when they're already in first period class. Teens often sleep in over the weekend, and many teen habits make it even harder to fall asleep which makes matters worse. But parents can help: it's especially important to set limits on the nighttime use of electronics. Studies have shown that the light from an tablet or cell phone can keep the brain in a waking, excited state. Quick naps late in the afternoon for 20 minutes or so can take the edge off and temporarily restore alertness.

A separate study published this month in the Journal of Pediatrics found that teenagers who don’t get enough sleep are more likely to become obese. Shakira Suglia of the Mailman School of Public Health at Columbia University and colleagues found that about a fifth of the 16-year-olds reported getting less than six hours of sleep a night, in a survey of 10,000 teens and young adults. Those with less sleep were 20 percent more likely to be obese by age 21, compared to their peers who got more than eight hours of sleep

 “Lack of sleep in your teenage years can stack the deck against you for obesity later in life,” Suglia said in a statement. “Once you’re an obese adult, it is much harder to lose weight and keep it off. And the longer you are obese, the greater your risk for health problems like heart disease, diabetes, and cancer.”

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"Infant sleep machines" could damage babies' hearing

Sleep machines are devices designed placed next to the baby's crib and designed to help babies sleep more soundly. They work by generating ambient or "white" noise, masking other noises from around the house or outside that could disturb the baby. Websites promoting these machines often suggest that parents and childminders should have the device on continually while a child is sleeping: a common recommendation is that the volume of the sounds played by the machine should be equal to or louder than the cry of an infant. Many parents say their babies become so used to the sounds of rainfall or birds that they will not nap without them.

But researchers at the University of Toronto evaluated 14 popular sleep machines at maximum volume and found they produced between 68.8 to 92.9 decibels at 30 centimeters, about the distance one might be placed from an infant’s head. Three exceeded 85 decibels, the workplace safety limit for adults on an eight-hour shift for accumulated exposure as determined by National Institute for Occupational Safety and Health. One machine was so loud that two hours of use would exceed workplace noise limits.

At 100 centimeters, all the machines tested were louder than the 50-decibel limit averaged over an hour set for hospital nurseries in 1999 by an expert panel concerned with improving newborn sleep and their speech intelligibility. 

As infants are still developing and have much smaller ear canals than adults, it is possible that babies are more susceptible to the adverse effects of noise levels than adults.

The researchers think that safe use of these devices could be possible, but only with policy recommendations that set appropriate limits on the manufacture and use of the devices.

They recommend that families using infant sleep machines should place the device as far away as possible from the baby, and never in the crib or on the rail of the crib, only play the sleep machine at a low volume and only play the sleep machine for a short duration of time.
The study authors also recommended that manufacturers limit the maximum noise level of infant sleep machines. 

Another concern briefly raised in the Pediatrics study is whether listening to white noise can be detrimental to auditory development. A 2003 study published in the journal Science found continuous white noise delayed development of the brain’s hearing center in newborn rats.

In humans, the brain of a newborn is learning to differentiate sounds at different pitches even during sleep, said Lisa L. Hunter, scientific director of research in the division of audiology at Cincinnati Children’s Hospital.

“If you’ve conditioned them to white noise, there’s every indication that they might not be as responsive as they otherwise should be to soft speech,” she said.

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References:
Infant Sleep Machines and Hazardous Sound Pressure Levels: PEDIATRICS ( journal of the American Academy of Pediatrics); March 3, 2014