Thursday, March 4, 2010

PITT-LED STUDY DEBUNKS MILLENNIA-OLD CLAIMS OF SYSTEMATIC INFANT SACRIFICE IN ANCIENT CARTHAGE

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A study led by University of Pittsburgh researchers could finally lay to rest the millennia-old conjecture that the ancient empire of Carthage regularly sacrificed its youngest citizens. An examination of the remains of Carthaginian children revealed that most infants perished prenatally or very shortly after birth and were unlikely to have lived long enough to be sacrificed, according to a Feb. 17 report in PLoS ONE.

The findings—based on the first published analysis of the skeletal remains found in Carthaginian burial urns—refute claims from as early as the 3rd century BCE of systematic infant sacrifice at Carthage that remain a subject of debate among biblical scholars and archaeologists, said lead researcher Jeffrey H. Schwartz, a professor of anthropology and history and philosophy of science in Pitt's School of Arts and Sciences and president of the World Academy of Art and Science. Schwartz and his colleagues present the more benign interpretation that very young Punic children were cremated and interred in burial urns regardless of how they died.

"Our study emphasizes that historical scientists must consider all evidence when deciphering ancient societal behavior," Schwartz said. "The idea of regular infant sacrifice in Carthage is not based on a study of the cremated remains, but on instances of human sacrifice reported by a few ancient chroniclers, inferred from ambiguous Carthaginian inscriptions, and referenced in the Old Testament. Our results show that some children were sacrificed, but they contradict the conclusion that Carthaginians were a brutal bunch who regularly sacrificed their own children."

Schwartz worked with Frank Houghton of the Veterans Research Foundation of Pittsburgh, Roberto Macchiarelli of the National Museum of Natural History in Paris, and Luca Bondioli of the National Museum of Prehistory and Ethnography in Rome to inspect the remains of children found in Tophets, burial sites peripheral to conventional Carthaginian cemeteries for older children and adults. Tophets housed urns containing the cremated remains of young children and animals, which led to the theory that they were reserved for victims of sacrifice.

Schwartz and his coauthors tested the all-sacrifice claim by examining the skeletal remains from 348 urns for developmental markers that would determine the children's age at death. Schwartz and Houghton recorded skull, hip, long bone, and tooth measurements that indicated most of the children died in their first year with a sizeable number aged only two to five months, and that at least 20 percent of the sample was prenatal.

Schwartz and Houghton then selected teeth from 50 individuals they concluded had died before or shortly after birth and sent them to Macchiarelli and Bondioli, who examined the samples for a neonatal line. This opaque band forms in human teeth between the interruption of enamel production at birth and its resumption within two weeks of life. Identification of this line is commonly used to determine an infant's age at death. Macchiarelli and Bondioli found a neonatal line in the teeth of 24 individuals, meaning that the remaining 26 individuals died prenatally or within two weeks of birth, the researchers reported.

The contents of the urns also dispel the possibility of mass infant sacrifice, Schwartz and Houghton noted. No urn contained enough skeletal material to suggest the presence of more than two complete individuals. Although many urns contained some superfluous fragments belonging to additional children, the researchers concluded that these bones remained from previous cremations and may have inadvertently been mixed with the ashes of subsequent cremations.

The team's report also disputes the contention that Carthaginians specifically sacrificed first-born males. Schwartz and Houghton determined sex by measuring the sciatic notch—a crevice at the rear of the pelvis that's wider in females—of 70 hipbones. They discovered that 38 pelvises came from females and 26 from males. Two others were likely female, one likely male, and three undetermined.

Schwartz and his colleagues conclude that the high incidence of prenate and infant mortality are consistent with modern data on stillbirths, miscarriages, and infant death. They write that if conditions in other ancient cities held in Carthage, young and unborn children could have easily succumbed to the diseases and sanitary shortcomings found in such cities as Rome and Pompeii.

University of Pittsburgh

RATE OF OCEAN ACIDIFICATION THE FASTEST IN 65 MILLION YEARS

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A new model, capable of assessing the rate at which the oceans are acidifying, suggests that changes in the carbonate chemistry of the deep ocean may exceed anything seen in the past 65 million years.

The model also predicts much higher rates of environmental change at the ocean’s surface in the future than have occurred in the past, potentially exceeding the rate at which plankton can adapt.

The research, from the University of Bristol, is reported in Nature Geoscience.

The team applied a model that compared current rates of ocean acidification with the greenhouse event at the Paleocene-Eocene boundary, about 55 million years ago when surface ocean temperatures rose by around 5-6°C over a few thousand years. During this event, no catastrophe is seen in surface ecosystems, such as plankton, yet bottom-dwelling organisms in the deep ocean experienced a major extinction.

Dr Andy Ridgwell, lead author on the paper, said: “Unlike surface plankton dwelling in a variable habitat, organisms living deep down on the ocean floor are adapted to much more stable conditions. A rapid and severe geochemical change in their environment would make their survival precarious.

“The widespread extinction of these ocean floor organisms during the Paleocene-Eocene greenhouse warming and acidification event tells us that similar extinctions in the future are possible.”

The oceans are currently absorbing about a quarter of the CO2 released into the atmosphere, forcing the pH of the surface ocean lower in a process called ‘ocean acidification’.

Laboratory experiments suggest that if the pH continues to fall, we may start to see impacts such as the dissolution of carbonate shells of marine organisms, slower growth, muscle wastage, dwarfism or reduced activity, with knock-on effects throughout the ecosystem.

Dr Daniela Schmidt, also an author on the paper, explained: “Laboratory experiments can tell us about how marine organisms react, but experiments cannot tell us whether marine organisms will be able to adapt to ocean acidification via migration or evolution.

“Therefore, a lot of attention has recently focussed on looking at known ocean acidification and biotic reactions in the geological record. Various types of geological evidence – the spread of warm water organisms towards the poles and the dissolution of carbonate sediments on the sea-floor tell us there was simultaneously both extreme warming and acidification at this time – the hallmark of a massive greenhouse gas release.”

On the basis of their approach of comparing model simulations of past and future marine geochemical changes, the authors infer a future rate of surface-ocean acidification and environmental pressure on marine calcifiers, such as corals, unprecedented in the past 65 million years, and one that challenges the potential for plankton to adapt.

They also argue that for organisms which live on the sea floor, rapid and extreme acidification of the deep ocean would make their situation uncertain. The occurrence of widespread extinction of these organisms during the Paleocene-Eocenegreenhouse warming and acidification event raises the possibility of a similar extinction in the future.

(Photo: Daniela Schmidt/JOIDES Resolution Drill Ship)

University of Bristol

WHAT THE BRAIN VALUES MAY NOT BE WHAT IT BUYS

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It’s no wonder attractive human faces are everywhere in media and advertising -- when we see those faces, our brains are constantly computing how much the experiences are worth to us.

New brain-imaging research shows it's even possible to predict how much people might be willing to pay for a particular face.

Researchers at Duke University Medical Center found that as participants were watching a sequence of faces, their brains were simultaneously evaluating those faces in two distinct ways: for the quality of the viewing experience and for what they would trade to see the face again.

The work was published in the Journal of Neuroscience online on February 16.

They showed college-aged men a parade of female faces, intermixed with images of money, while measuring brain activation using functional magnetic resonance imaging (fMRI). In a later experiment, the same participants could pay more or less money to view more or less attractive faces.

“One part of the frontal cortex of our participants’ brains increased in activation to more attractive faces, as if it computed those faces’ hedonic (quality of the experience) value," said senior author Scott Huettel, PhD, an associate professor of psychology and neuroscience who directs the Center for Neuroeconomic Studies at Duke. "A nearby brain region’s activation also predicted those faces’ economic value -- specifically, how much money that person would be willing to trade to see another face of similar attractiveness.”

During the fMRI experiment, heterosexual men viewed a set of female faces that had previously been rated for attractiveness by peers. Interspersed with the face pictures were pictures of money, shown in several denominations, which indicated real monetary gains or losses that the participant could later spend during the next phase of the experiment.

The participants made a series of economic decisions: Should they spend more of their money to see a more attractive face, or spend less money but see a less attractive face? Each participant made about one hundred of these decisions, spending from one to 12 cents each time.

The researchers measured fMRI activation while the participants viewed the faces and money. In a region near the front of the brain, the anterior ventromedial prefrontal cortex (VMPFC), there was increased activation when participants saw a more attractive face or saw a picture of a larger amount of money. That pattern of brain activation was relatively stable across participants in the study.

Yet, slightly farther back in the brain, within posterior VMPFC, the researchers also could see the relative activation to the faces compared to money, which strongly predicted how each person would later spend to see a more attractive face.

Huettel said that findings from neuroscience might lead to new directions in marketing. “People often respond to images in a very idiosyncratic fashion," he said. "While we can’t use neuroscience to identify the best images for every person’s brain, we could identify types of images that tend to modulate the right sorts of value signals -- those that predict future purchases for a market segment.”

Lead author David V. Smith, a graduate student in psychology and neuroscience, explained further: “Previous studies have shown that active decisions about the value of real goods, such as candy or consumer products, evoke activation in the VMPFC. Our study demonstrates that the VMPFC actually contains two signals for value: one that indicates how much value we are currently experiencing, and another that indicates how much we’d be willing to pay to have that experience again later.”

Why were all subjects male? “For this new study, we built on prior work from colleagues who showed that young adult males not only value the experience of seeing a female face, but will treat that experience like an economic good -- they will trade experience for money in a predictable manner,” Huettel said. “We expect that the functioning of the brain’s reward system is essentially similar between males and females. However, what sorts of stimuli seem attractive -- whether an image of a face or some other social cue -- may differ between the genders.”

Smith added that they plan to continue the research with other kinds of rewards, including different types of pictures. “A key issue in future research will be examining how different value signals are communicated between different parts of the brain to produce our decisions,” Smith said.

Duke University

CHICKENS 'ONE-UP' HUMANS IN ABILITY TO SEE COLOR

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Researchers at Washington University School of Medicine in St. Louis have peered deep into the eye of the chicken and found a masterpiece of biological design.

Scientists mapped five types of light receptors in the chicken's eye. They discovered the receptors were laid out in interwoven mosaics that maximized the chicken's ability to see many colors in any given part of the retina, the light-sensing structure at the back of the eye.

"Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision," says Joseph C. Corbo, M.D., Ph.D., senior author and assistant professor of pathology and immunology and of genetics. "Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas."

Corbo plans follow-up studies of how this organization is established. He says such insights could eventually help scientists seeking to use stem cells and other new techniques to treat the nearly 200 genetic disorders that can cause various forms of blindness.

Scientists published their results in the journal PLoS One.

Birds likely owe their superior color vision to not having spent a period of evolutionary history in the dark, according to Corbo. Birds, reptiles and mammals are all descended from a common ancestor, but during the age of the dinosaurs, most mammals became nocturnal for millions of years.

Vision comes from light-sensitive photoreceptor cells in the retina. Night-vision relies on receptors called rods, which flourished in the mammalian eye during the time of the dinosaurs. Daytime vision relies on different receptors, known as cones, that are less advantageous when an organism is most active at night.

Birds, now widely believed to be descendants of dinosaurs, never spent a similar period living mostly in darkness. As a result, birds have more types of cones than mammals.

"The human retina has cones sensitive to red, blue and green wavelengths," Corbo says. "Avian retinas also have a cone that can detect violet wavelengths, including some ultraviolet, and a specialized receptor called a double cone that we believe helps them detect motion."

In addition, most avian cones have a specialized structure that Corbo compares to "cellular sunglasses": a lens-like drop of oil within the cone that is pigmented to filter out all but a particular range of light. Researchers used these drops to map the location of the different types of cones on the chicken retina. They found that the different types of cones were evenly distributed throughout the retina, but two cones of the same type were never located next to each other.

"This is the ideal way to uniformly sample the color space of your field of vision," Corbo says. "It appears to be a global pattern created from a simple localized rule: you can be next to other cones, but not next to the same kind of cone."

Corbo speculates that extra sensitivity to color may help birds in finding mates, which often involves colorful plumage, or when feeding on berries or other colorful fruit.

"Many of the inherited conditions that cause blindness in humans affect cones and rods, and it will be interesting to see if what we learn of the organization of the chicken's retina will help us better understand and repair such problems in the human eye," Corbo says.

(Photo: WUSTL)

Washington University in St. Louis

DARK MATTER OR BACKGROUND NOISE? RESULTS INTRIGUING BUT NOT CONCLUSIVE

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Physicists may have glimpsed a particle that is a leading candidate for mysterious dark matter but say conclusive evidence remains elusive.

A 9-year search from a unique observatory in an old iron mine 2,000 feet underground has yielded two possible detections of weakly interacting massive particles, or WIMPs. But physicists, who include two University of Florida researchers, say there is about a one in four chance that the detections were merely background noise — meaning that a worldwide hunt involving at least two dozen different observatories and hundreds of scientists will continue.

“With one or two events, it’s tough. The numbers are too small,” said Tarek Saab, a UF assistant professor and one of dozens of physicists participating in the Cryogenic Dark Matter Search II, or CDMS II, experiment based in the Soudan mine in Northern Minnesota.

A paper about the results is set to appear Thursday in Science Express, the journal Science’s Web site for selected papers that appear in advance of the print publication.

Scientists recognized decades ago that the rotational speed of galaxies and the behavior of galaxy clusters could not be explained by the traditional forces of gravity due to the mass of visible stars alone. Something else — something invisible, undetectable yet extremely powerful — had to exert the force required to cause the galaxies’ more-rapid-than-expected rotational speed and similar anomalous observations.

What came to be known as “dark matter” — dark because it neither reflects nor absorbs light in any form, visible or other — is now estimated to comprise as much as 23 percent of the universe. But despite abundant evidence for its influence, no one has ever observed dark matter directly.

There are several possibilities for the composition of this mysterious, omnipresent matter. Particle physics theory points toward WIMPs as one of the most likely candidates.

WIMPs are “weakly interacting” because, although their masses are thought to be comparable to the masses of standard atomic nuclei, they have little or no effect on ordinary matter.

Among other things, that makes them extremely difficult to detect.

However, scientists believe WIMPs should occasionally “kick” or bounce off standard atomic nuclei, leaving behind a small amount of energy that should be possible to detect.

The CDMS II observatory is located a half-mile underground beneath rock that blocks most particles, such as those accompanying cosmic rays. At the observatory’s heart are 30 hockey-puck-sized germanium and silicon detectors cryogenically frozen to negative 459.58 Fahrenheit, just shy of absolute zero. In theory, WIMPs would be among the few particles that make it all the way through the earth and rock. They would then occasionally kick the atoms on these detectors, generating a tiny amount of heat, a signal that would be observed and recorded on the experiment’s computers.

Durdana Balakishiyeva, a postdoctoral associate in physics at UF, and Saab have participated in the analysis of data produced by the experiment as well as simulations of the detectors’ response. Beginning in 2007 they have helped to test many of the detectors at the UF campus in Gainesville which are being used in the successor SuperCDMS experiment. The UF tests involved cooling and operating the detectors just as they are operated in Minnesota to verify that they were up to par.

The 15 institutions participating in CDMS II gathered data from 2003 to 2009. Observers recorded the two possible WIMP events in 2007, one on Aug. 8 and the second on Oct. 27. Scientists had estimated that five detections would be sufficient to confirm WIMPs — meaning that the two fell short, according to the CDMS. But while the two detections may not be conclusive, they do help to set more stringent values on the WIMPs’ interaction with subatomic particles.

“Up until now, not only us, but everybody was operating without statistics — we were blind in that sense,” Balakishiyeva said. “But now we can speak of statistics in some way.”

At the very least, the finding helps to eliminate some theories about dark matter — raising the profile of the WIMP and potentially accelerating the race to detect it.

“Many people believe we are extremely close — not just us, but other experiments,” Saab said. “It is expected or certainly hoped that in the next five years or so, someone will see a clear signal.”

University of Florida

RADICAL NEW DIRECTIONS NEEDED IN FOOD PRODUCTION TO DEAL WITH CLIMATE CHANGE

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Yields from some of the most important crops begin to decline sharply when average temperatures exceed about 30 degrees Celsius, or 86 Fahrenheit. Projections are that by the end of this century much of the tropics and subtropics will regularly see growing season temperatures above that level, hotter than the hottest summers now on record.

An international panel of scientists writing in the Feb. 12 edition of the journal Science is urging world leaders to dramatically alter their notions about sustainable agriculture to prevent a major starvation catastrophe by the end of this century among the more than 3 billion people who live relatively close to the equator.

Specifically they urge world leaders to "get beyond popular biases against the use of agricultural biotechnology," particularly crops genetically modified to produce greater yields in harsher conditions, and to base the regulations of such crops on the best available science.

"You're looking at a 20 percent to 30 percent decline in production yields in the next 50 years for major crops between the latitudes of southern California or southern Europe to South Africa," said David Battisti, a University of Washington atmospheric sciences professor.

He is a coauthor of a Perspectives article in Science that urges food production experts, scientists and world leaders to begin thinking in dramatically different ways to meet food needs in a significantly warmer world. Lead author is Nina Federoff, science and technology adviser to Secretary of State Hillary Rodham Clinton.

"I grow increasingly concerned that we have not yet understood what it will take to feed a growing population on a warming planet," said Federoff, who also is a biology professor at Pennsylvania State University.

The challenge is becoming more difficult, the scientists said, because the world's population is likely to have increased more than 30 percent, to 9 billion people, by 2050.

Even without climate change, feeding all of these people will require doubling the grain production in the tropics, Battisti said, but a warmer climate will reduce yields because the temperature will be too high to achieve the most efficient photosynthesis. That factor, combined with less rainfall in major food-producing regions and increasing pressure from pests and pathogens, is likely to cut major food crop yields a minimum of 20 percent to 30 percent.

The authors advocate developing systems that have the potential to decrease the land, energy and fresh water needed for agriculture and at the same time reducing the pollution associated with agricultural chemicals and animal waste.

Battisti noted that the so-called green revolution in agriculture produced a 2 percent increase in yields per year for 20 years, primarily through development of new grain varieties and use of fertilizer and irrigation. But there is little, if any, new land available for farming, and such yield increases cannot be sustained without further innovation. In addition, there already are 1 billion people, mostly in the tropics, who do not have enough food for a healthy life.

"We're really asking for yield gains comparable to those at the peak of the green revolution, but sustained for an unprecedented length of time, 40 years, and at a time when climate change is acting against us," he said.

A major obstacle is that many of the institutions involved do not work together closely enough to succeed and, despite years of safe production and consumption, there is continued resistance to crops such as corn and soybeans that have been genetically modified to be insect resistant and tolerant of herbicides.

"There has to be a lot of creative thinking, a greater blending of biotechnology and agriculture and better coordination between private and public research efforts throughout the world for us to keep pace with the increasing demand for food," Battisti said. "We need to be thinking about the long-term demands for food and the environmental and social ramifications of how we will produce it."

University of Washington

CLAY FIGURES ARE MISSING LINK IN HISTORY OF AFRICA

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Eighty ancient clay figures have been discovered by archaeologists at The Universities of Manchester and Ghana, showing that a sophisticated society - now forgotten - once existed in West Africa.

They are the latest - and most impressive - batch of the beautifully sculpted human and animal figures, between 1400 and 800 years old, unearthed from a series of mysterious mounds in a remote region of Northern Ghana.

The mounds, which also contain human skulls, are thought by Ghana's Dr Benjamin Kankpeyeng and Manchester's Professor Tim Insoll to be the sites of ancient shrines.

Using state of the art analysis of the number, context and arrangement of the figurines, Dr Kankpeyeng and Professor Insoll hope to gain insight into the past ritual practices and beliefs of this sophisticated society - filling in a gap in our knowledge of that period in Africa.

Hundreds of mounds are densely packed in an area only 30km square: it took just two weeks to excavate the 80 figures in January.

But illegal excavation of the treasures means the archaeologists are in a race against time to ensure they are safely removed.

"These finds will help to fill a significant gap in our scant knowledge of this period before the Islamic empires developed in West Africa ," said Prof Insoll.

"They were a sophisticated and technically advanced society: for example some of the figurines were built in sections and slotted together.”

Dr Kankpeyeng said: "The relative position of the figurines surrounded by human skulls means the mounds were the location of an ancient shrine.

"The skulls had their jaw bones removed with teeth placed nearby - an act of religious significance."

Prof Insoll is to carry out analysis funded by the Wellcome Trust of the residues of material which were packed into holes within the figurines to provide more clues about the society.

He said: "We are certain these people filled the holes with something - but the question is was it medicinal substances, or blood or other material from a sacrifice?

"It's the first time such analysis is being done, with the help of colleagues from the University's School of Earth, Atmospheric and Environmental Sciences."

The first excavation of the burial sites took place in 1985 with others in 2007, 2008 and 2009 carried out by The University of Ghana.

Some of the figures have been taken out of Ghana - with permission of the authorities - for analysis in Manchester by Prof Insoll who joined the project this year.

He said: "There are still many questions remaining: some of the figurines were deliberately broken and placed besides body parts. Why?"

Dr Kankpeyeng said: "What is interesting is that the people now living in this area seem to have no connection with the makers of the figurines".

"That would suggest that that they have more in common with peoples living in other parts of West Africa - but we need to do more work before we can be certain".

(Photo: University of Manchester)

University of Manchester

PROTEIN STUDY SHOWS EVOLUTIONARY LINK BETWEEN PLANTS, HUMANS

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Inserting a human protein important in cancer development was able to revive dying plants, showing an evolutionary link between plants and humans and possibly making it easier to study the protein's function in cancer development, a Purdue University study has shown.

The aminopeptidase M1 protein, or APM1, is critical for root development in plants. Arabidopsis plants lacking the protein will die, but can be rescued if the protein is restored.

During experiments, Wendy Peer, a research assistant professor of horticulture, found that inserting a similar protein found in humans, called insulin responsive aminopeptidase, or IRAP, also rescued the plants.

"APM1 and IRAP are in the same group," said Peer, whose results were published in the early online version of the journal Plant Physiology. "M1 aminopeptidase activity is such a fundamental process that it's been conserved evolutionarily. This protein has changed very little over time."

Peer said the finding could advance the understanding of this class of proteins because it might make it possible to conduct studies with plants instead of animals, offering researchers more control and options. Humans with altered function of the equivalent proteins often have leukemia or other cancers.

"There are more tools available in Arabidopsis to study this class of proteins than are available in animals," Peer said. "This research could be translational and helpful in the animal field or with human health. If humans have changes in these peptidases, they're very sick. Understanding how these proteins work in plants will help us understand how they work in humans."

APM1's function isn't entirely understood in plants. M1 aminopeptidases are thought to remove amino acids from proteins, thereby either activating or deactivating those proteins. M1 aminopeptidases also break down accumulations of proteins related to Alzheimer's disease.

"APM1 can alter the function of other proteins with its activity," Peer said.

Peer wants to understand which proteins APM1 targets and how it changes those proteins, thereby affecting changes in a plant's development. She is working to discover which amino acids in APM1 are necessary for it to function.

Peer and Angus Murphy, a Purdue professor of horticulture, have been working on this problem for several years. They identified Arabidopsis mutants that were missing APM1 and inserted modified APM1 proteins missing particular amino acids into the mutants to determine whether the modified APM1 protein could rescue the seedlings.

The next step in Peer's research is to determine APM1's target protein to better understand why APM1 is important for root growth. The National Science Foundation funded the research.

Purdue University

LACK OF MORNING LIGHT KEEPING TEENAGERS UP AT NIGHT

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The first field study on the impact of light on teenagers’ sleeping habits finds that insufficient daily morning light exposure contributes to teenagers not getting enough sleep.

“As teenagers spend more time indoors, they miss out on essential morning light needed to stimulate the body’s 24-hour biological system, which regulates the sleep/wake cycle,” reports Mariana Figueiro, Ph.D., Assistant Professor and Program Director at Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) and lead researcher on the new study.

“These morning-light-deprived teenagers are going to bed later, getting less sleep and possibly under-performing on standardized tests. We are starting to call this the teenage night owl syndrome.”

In the study just published in Neuroendocrinology Letters, Dr. Figueiro and LRC Director Dr. Mark Rea found that eleven 8th grade students who wore special glasses to prevent short-wavelength (blue) morning light from reaching their eyes experienced a 30-minute delay in sleep onset by the end of the 5-day study.

“If you remove blue light in the morning, it delays the onset of melatonin, the hormone that indicates to the body when it’s nighttime,” explains Dr. Figueiro. “Our study shows melatonin onset was delayed by about 6 minutes each day the teens were restricted from blue light. Sleep onset typically occurs about 2 hours after melatonin onset."

The problem is that today’s middle and high schools have rigid schedules requiring teenagers to be in school very early in the morning. These students are likely to miss the morning light because they are often traveling to and arriving at school before the sun is up or as it’s just rising. “This disrupts the connection between daily biological rhythms, called circadian rhythms, and the earth’s natural 24-hour light/dark cycle,” explains Dr. Figueiro.

In addition, the schools are not likely providing adequate electric light or daylight to stimulate this biological or circadian system, which regulates body temperature, alertness, appetite, hormones and sleep patterns. Our biological system responds to light much differently than our visual system. It is much more sensitive to blue light. Therefore, having enough light in the classroom to read and study does not guarantee that there is sufficient light to stimulate our biological system.

“According to our study, however, the situation in schools can be changed rapidly by the conscious delivery of daylight, which is saturated with short-wavelength, or blue, light,” reports Dr. Figueiro.

Dr. Figueiro’s research, sponsored by the U.S. Green Building Council and in part by a grant from a Trans-National Institutes of Health Genes, Environment and Health Initiative is the first field study to measure the impact of reduced morning blue light exposure on evening melatonin onset of teenagers attending school.

According to Dr. Figueiro, the results of this field study are significant because they validate controlled laboratory findings with actual field measurements of light that impact our biological system.

The field experiment was conducted at Smith Middle School in Chapel Hill, North Carolina, a school with good daylight design. The school building has south-facing skylights to deliver daylight to nearly all interior spaces throughout the day.

The study detailed in Neuroendocrinology Letters is part of a larger study where data on students was collected at both Smith Middle School in Chapel Hill, North Carolina, as well as Algonquin Middle School in Averill Park, New York.

The larger study is examining not only the impact of removing morning blue light, but also the seasonal impact and the increased evening light exposure during the spring months on teens’ melatonin onset and sleep times.

Throughout her research, Dr. Figueiro has repeatedly come face-to-face with the enormous concern of parents over teenagers going to bed too late. “Our findings pose two questions: “How will we promote exposure to morning light and how will we design schools differently?” says Dr. Figueiro.

The study findings should have significant implications for school design. “Delivering daylight in schools may be a simple, non-pharmacological treatment for students to help them increase sleep duration,” concludes Dr. Figueiro.

The new research has applications for more than 3 million shift workers and Alzheimer’s patients who suffer from lack of a regular sleep pattern.

Studies have shown that this lack of synchronization between a shift worker’s rest and activity and light/dark patterns leads to a much higher risk of cardiovascular disease, diabetes, seasonal depression and cancer over decades.

As evidenced in prior studies by Dr. Figueiro, light therapy can also be used to improve sleep in Alzheimer’s patients, who usually display uneven sleep patterns. “By removing light at certain times of day, and giving light at other times, you can synchronize the sleep/wake patterns of Alzheimer’s patients with the light/dark pattern, providing them with more consolidated sleep,” says Dr. Figueiro.

(Photo: Caltech/Michael Kelzenberg)

Rensselaer Polytechnic Institute

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