IELTS reading practice test 3

Why teenagers can't get up in the morning

A Parents have long complained that teenagers stay up late and are impossible to wake in the morning. For many years this was put down to poor habits, late-night screens or simple laziness. Sleep researchers now believe that something more fundamental is going on: during adolescence, the body clock itself shifts later.

B The timing of sleep is controlled partly by melatonin, a hormone released by the brain as evening approaches. In young children, melatonin levels rise early in the evening. Studies that measured the hormone in saliva found that, in teenagers, the rise happens up to two hours later. As a result, a fifteen-year-old who goes to bed at ten o'clock may simply lie awake, not because they are unwilling to sleep but because their body is not yet ready.

C At the same time, the need for sleep does not fall during the teenage years. Most experts recommend between eight and ten hours a night for this age group. When early school start times are combined with a late body clock, the result is a large and regular shortfall. Surveys in several countries suggest that a majority of secondary students get less than eight hours on school nights, and many try to 'catch up' by sleeping late at weekends, which can push their body clock even later.

D The consequences go beyond tiredness. Teenagers who are short of sleep tend to find it harder to concentrate and remember new information, and some research links lack of sleep with low mood and a greater risk of accidents among young drivers. One researcher, Dr Helen Marsh, has described chronic sleep loss in adolescents as 'a public health issue hiding in plain sight'.

E A number of school districts have experimented with later start times. In one widely reported trial in the United States, secondary schools moved the start of the school day from 7.50 am to 8.45 am. Students' average sleep increased by around forty minutes a night, attendance improved and fewer students reported falling asleep in class. Similar trials elsewhere have produced more modest results, partly because some students used the extra time to go to bed later.

F Changing school timetables is not straightforward. Later finishing times can clash with sport, part-time work and family routines, and bus services may need to be reorganised. Some researchers therefore argue that schools should combine later starts with education about sleep, for example encouraging students to keep regular hours at weekends and to reduce bright light from screens late in the evening.