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Why adolescence is lasting twice as long as it did in the 1950s

5 January 2018

Children are hitting puberty earlier than ever before. Psychology professor Laurence Steinberg explained why to Brainwaves.

Plastic fantastic

Professor Laurence Steinberg

Prof. Laurence Steinberg explains the importance of brain plasticity during adolescence

Child to adult

Adolescence is the period of life between starting puberty and becoming stable, independent adults. But this time is being extended because children are beginning puberty earlier.

Adolescence is three times as long as it was in the 19th Century and it’s twice as long as it was in the 1950s.
Professor Laurence Steinberg

According to Professor Steinberg, in the western world adolescence effectively runs from age 10 or so to about age 25.

Professor Steinberg attributed the lengthening of adolescence to several surprising factors.


“The first and most important is obesity. We know that kids who are fatter go through puberty earlier than kids who are leaner,” he said.


“There are other factors as well. One has to do with the exposure of children to endocrine-disrupting chemicals in the man-made environment. These chemicals are not just in food, they’re in cosmetics, they’re in plastics, they’re in pesticides — they’re ubiquitous.”

“We know that when people are exposed to these endocrine disrupters it alters their hormonal development and many of these chemicals lead to earlier onset puberty, especially in girls.”

Light exposure

“The third factor that’s only been discovered fairly recently has to do with exposure to light.”

Light from our phones impacts our brains

“It turns out that kids who grow up near the equator go through puberty earlier than kids who grow up near the north or south pole and that’s because, when you grow up near the equator, you have more exposure to sunlight over the course of your childhood years.”

And while that may not be of too much concern to parents in northern Europe, recent research suggests a final factor which applies to many children here.

“Scientists have discovered recently that the light that emanates from tablets or smartphones or computer screens can also affect the onset of puberty by disrupting the brain’s melatonin system.

“So as kids spend more and more time in front of these screens – especially in front of the blue light that’s emitted by many of these devices – that has probably contributed to earlier puberty as well.”


Adolescent angst

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