Teen Sleep Study Adds to Evidence of a 'Neural Fingerprint'
May 2, 2011
Science Daily/Brown University
New research finds that consistent, "signature" brainwave patterns first noticed in short-term studies of adults are so robust that they're also detectable over a matter of years in the notoriously turbulent brains of teens. From there, the question is what such a "neural fingerprint" might mean.
Teens are rarely described as stable, so when something about their rapidly changing brains remains placidly unaltered, neuroscientists take notice. Such is the case in a new study of electroencephalography (EEG) readings gathered from dozens of teens while they slept. Despite the major neural overhaul underway during adolescence, most individuals maintained a unique and consistent pattern of underlying brain oscillations. The work lends a new level of support to the idea, already observed in adults, that people produce a kind of brainwave "fingerprint."
"At the moment it's too soon to tell anything about individual sleep or behavior from this, but it could provide a tool to geneticists," she said. "It is a link between behavior and genes."
With further research, the functional or physiological significance of the patterns could become clearer, Carskadon said. One question would be whether particular influences such as sleep deprivation or alcohol use affect the pattern.
"Knowing this gives us another tool to examine brain function and stability," Carskadon said. "Showing that there are these fingerprints may open up future possibilities in using this kind of analysis in larger samples to look for endophenotypes that might be predictive of someone, say, who might go on to develop schizophrenia or depression."
http://www.sciencedaily.com/releases/2011/04/110426185251.htm
Exposure to early evening sunlight in spring creates teenage night owls
July 26, 2010
Science Daily/Rensselaer Polytechnic Institute
In the spring, later sunset and extended daylight exposure delay bedtimes in teenagers, according to new research.
"Biologically, this increased exposure to early evening light in the spring delays the onset of nocturnal melatonin, a hormone that indicates to the body when it's nighttime," explains Mariana Figueiro, Ph.D., associate professor. "This extended exposure adds to the difficulties teens have falling asleep at a reasonable hour."
Over time when coupled with having to rise early for school, this delay in sleep onset may lead to teen sleep deprivation and mood changes, and increase risk of obesity and perhaps under-performance in school, according to Figueiro.
"This is a double-barreled problem for teenagers and their parents," says Figueiro. "In addition to the exposure to more evening daylight, many teens also contend with not getting enough morning light to stimulate the body's biological system, also delaying teens' bedtimes."
Measuring "Circadian Light"
In the study, the Algonquin Middle School students were exposed to significantly more "circadian light" in the early evening during spring than in winter, resulting in both delayed melatonin onset and shorter self-reported sleep durations. Each subject wore a Daysimeter, a small, head-mounted device developed by the LRC to measure an individual's exposure to daily "circadian light," as well as rest and activity patterns. The definition of circadian light is based upon the potential for light to suppress melatonin synthesis at night, as opposed to measuring light in terms of how it stimulates the visual system.
This study, sponsored by the U.S. Green Building Council (USGBC) and, in part, by a grant from a Trans-National Institutes of Health Genes, Environment and Health Initiative (NIH-GEI), is the first to relate field measurements of circadian light exposures to a well-established circadian marker (the rise in evening melatonin levels) during two seasons of the year.
In a previous field study, also funded by USGBC and NIH-GEI and published in Neuroendocrinology Letters, Figueiro and Rea examined the impact of morning light on teen sleep habits and found that removing short-wavelength (blue) morning light resulted in a 30-minute delay in sleep onset by the end of a five-day period.
http://www.sciencedaily.com/releases/2010/07/100726124420.htm