By Joe Hadsall
Globe Features Editor
JOPLIN, Mo. —
Thanks to a recent scientific study, some common sense about teens and sleep received quantifiable confirmation.
Extended hours of daylight in the spring lead to later bedtimes for teens, causing them to be sleepier in the morning, researchers reported Tuesday.
“This is something that the scientific community has known all along,” said Rick LaTurner, coordinator of the sleep lab at St. John’s Regional Medical Center. “But it’s not a waste. It’s good to apply data to what we knew.”
Researchers from the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., concluded that delays in melatonin production by teens’ bodies leads to the later bedtimes.
Jeff Keener, director of the sleep center at Freeman Health System, said the same logic should apply to the upcoming change of season. When fall gives way to winter, the earlier nights should send teens to bed earlier Ñ though he said there’s no similar scientific data to back that up.
“It does work both ways,” Keener said. “When light goes away sooner, melatonin levels come on quicker.”
Teens have a delayed sleep phase, LaTurner said.
“When we start out as infants, we sleep most of the time,” LaTurner said. “As we move toward adolescence, we’re not as sleepy as we used to be.”
The chemical trigger is melatonin, a naturally occurring hormone that regulates sleep on a 24-hour cycle. Normally, melatonin levels start rising two to three hours before the onset of sleepiness.
Sunlight interferes with melatonin production, however, and can disrupt that cycle. The same team reported earlier this year, for example, that preventing exposure of teens to bright lights in the morning could cause a 30-minute delay in sleep onset, leading to excessive daytime sleepiness.
Sleep researchers Mariana G. Figueiro and Mark Rea, director of the lighting center, studied 16 eighth-grade students at Algonquin Middle School in upstate New York, fitting them with a small head-mounted device that measured exposure to sunlight as well as rest and activity patterns. They also measured blood levels of melatonin in the students.
They reported in the journal Chronobiology International that the teens experienced a 20-minute delay in the onset of melatonin on one day in spring compared with a day in winter. Sleep logs kept by the students indicated that the delay in melatonin onset was accompanied by a 16-minute delay in sleep onset and a 15-minute reduction in sleep duration.
Over time, when coupled with having to rise early for school, this delay in sleep onset may lead to sleep-deprivation and mood changes and increase the risk of obesity, Figueiro said.
Parents can keep their teens on a good cycle by keeping things as consistent as possible, LaTurner said.
“Teens get harder to control as they get older, so as much as possible, they need a consistent bedtime,” LaTurner said. “Turn the TV and lights off, and make the room dark for when they are ready to go to sleep.”
Teens struggling with getting to sleep on time should avoid using computers or watching TV about an hour before bedtime, Keener said.
“It’s considered bad sleep hygiene,” Keener said. “If you’re spending time in front of a screen an hour before bedtime, it causes the brain to be delayed, and it’s hard to get tired.”
LaTurner also said that over-the-counter sleep aids, such as medicines or supplements, should be avoided. If a teen has problems sleeping, it’s best to get them to a doctor, he said.
Thomas H. Maugh II, of McClatchy-Tribune News Service, contributed to this report.
