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Last updated at 18:52 BST, Thursday, 19 April 2012

Sleepy teenagers

Summary

19 April 2012

Teenagers are renowned for enjoying lengthy lie-ins in the morning. But contrary to popular belief, their reluctance to get out of bed may not be just down to laziness alone.

Reporter

Jenny Hill

Sleepy teenager

Scientists found that the teenagers get just six and a half hours sleep a night.

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Report

This bedroom is a battleground. Morgan's 17, and like most other teenagers, she struggles to surface.

Noelle Delaney, Mother:

Some days it is very difficult…you know I have to go in there two, three times. I have been known to pull her by her feet out of her bed.

Morgan Delaney, Student:

It's too early to get up in the morning, especially in the winter when it's quite dark out. It just seems like you're getting up in the middle of the night, you just want to be back in bed.

And that's why sleep scientists studied Morgan and her friends for two weeks. These wrist-mounted sensors monitored their every move – waking and sleeping.

Analysis of that data surprised the scientists. They found that consistently the teenagers get just six and a half hours sleep a night. Most adults need at least eight. When the clocks moved forward to British Summer Time the youngsters got even less – just six hours a night.

Joanne Bower, University of Surrey:

You've got something inside you called your circadian rhythm [body clock] which insures the same thing happens the same time every day and one of those things is the secretion of melatonin which is the hormone that makes you sleepy. Now for an adult you expect that to be early evening, in teenagers it happens much later so even if you put your teenager in bed at say ten at night it may be that they don't secrete their melatonin until midnight, one o'clock, so they're staring at the ceiling just not sleepy.

Consistent sleep deprivation can affect concentration, memory or even mood. The scientists behind this study say more research is needed because, like Morgan, most teenagers have busy lives - what they're not getting is enough rest.

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Vocabulary

battleground

a place where conflicts or fights take place

to surface

to wake up

sensors

devices that can recognise movement

monitored

watched or checked

analysis

detailed study

consistently

repeatedly

British Summer Time

a time zone in the UK where clocks are put forward by an hour in summer to make the most of the daylight hours

secretion

the process by which a liquid or a chemical is released by the body

hormone

a chemical produced in the body that influences how the cells and tissue function

sleep deprivation

lack of enough sleep