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January 2011



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By Rick Nauert PhD Senior News Editor
Reviewed by John M. Grohol, Psy.D. on February 17, 2010

As many a parent would confirm, some teens would prefer to stay up all night, then sleep past noon –- every day.

Researchers have studied this behavior and now believe 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., 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 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.”

Disrupting Biological Rhythms

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.

Source: Rensselaer Polytechnic Institute (RPI)

Focus On Fun Gets Teens Active – British Psychological Society

Article Date: 17 Feb 2010 – 3:00 PST

Emphasising the emotional benefits of exercise is more effective at increasing levels of physical activity than highlighting traditional health benefits. This is the finding of research published online today, 17th February 2010, in the British Journal of Health Psychology.

The study was carried out by Reema Sirriyeh and colleagues from the University of Leeds. Reema said: “There is evidence that people who believe that physical activity is enjoyable and fun are more likely to engage in sport and exercise. We investigated whether highlighting the emotional benefits of sport and exercise to young people increased their levels of physical activity, more than highlighting the physical health benefits.”

128 participants aged 16 to 19 took part in the study; all were recruited from the sixth forms of four schools in West Yorkshire. The teenagers all received a daily text message at 4pm for a period of two weeks. Some teens received text messages that highlighted either the emotional benefits of exercise – such as ‘Physical activity can make you feel cheerful. What activity will you do today?’ , a second group received texts that highlighted the physical benefits, such as – ‘Physical activity can keep your heart healthy. What activity will you do today?’ and a further group received text messages that were a combination of the two.

The participants recorded their levels of physical activity using the International Physical Activity Questionnaire (IPAQ), which measured the time they spent on of moderate and vigorous exercise.

Analysis of the results found that the physical activity levels of all 128 participants increased after the two-week intervention by an average 31.5 minutes of moderate activity a week. The largest increase in physical activity was seen for inactive teenagers who received the text messages that highlighted the emotional benefits of exercise. This was equivalent to 120 more minutes of moderate exercise.

Reema continued: “Statistics from the British Heart Foundation show that from the age of 16, girls’ levels of physical activity begin to decrease. As patterns of behaviour that start in the teenage years tend to persist into adulthood, it’s vitally important that teenagers get into healthy patterns, like taking regular exercise. Our study shows that for inactive teenagers, emphasising the emotional benefits of exercise may be a more effective way to encourage exercise than highlighting traditional health benefits.”

British Psychological Society



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