Why are teens always tired?

In fact, the opposite is true. Sleep experts say teens today are sleeping less than they ever have. This is a worry, as there's a link between sleep deprivation and accidents, obesity and cardiovascular diseases.

Physiological changes, social pressures and external factors, such as mobiles and other stimulating gadgets in the bedroom, contribute to late nights and mood swings.

Lack of sleep also affects teenagers' education, as it can leave them too tired to concentrate in class and perform to their best ability in exams.

Teenagers' sleep patterns

Our sleep patterns are dictated by light and hormones. When light dims in the evening, we produce a chemical called melatonin, which gives the body clock its cue, telling us it’s time to sleep.

“The problem is that society has changed,” says Professor Paul Gringras, consultant paediatrician and director of the Evelina Paediatric Sleep Disorder Service at Guy’s and St Thomas’ Hospital in London.

“Artificial light has disrupted our sleep patterns. Bright room lighting, TVs, games consoles, mobiles, tablets and PCs can all emit enough light to stop the natural production of melatonin.” These are all distractions, which teens may use well into the night.

“That wouldn’t be a problem if there was no need to get up early in the morning for school,” says Professor Gringras.

“The early morning wake-ups mean they’re not getting the average eight to nine hours of sleep. The result is a tired and cranky teenager.”

Several school districts in the US have introduced later start times for pupils in an effort to improve their performance, although results have been mixed.

Sleep problems and the body clock

"Catching up on sleep at weekends isn’t ideal. Late nights and long lie-ins further disrupt the body clock," says Professor Gringras.

In severe cases, an individual’s body clock can be so different to everyone else's that they can’t fall asleep until late at night. This condition is called delayed sleep phase syndrome (DSPS). It's similar to the feeling of jet lag and is a disorder of the body’s timing system.

Treatment for DSPS includes bright light therapy – such as exposure to a bright light for around half an hour every morning – and chronotherapy, which involves restoring the individual’s natural sleep phase.

“Sometimes we give a small dose of melatonin in the evening, about an hour or so before bedtime,” says Professor Gringras. “Over the long term, this helps to reset the body clock.”

“However tired they feel, they should avoid lie-ins at the weekend. They should get exposure to outdoor light,” he says.

Getting help for sleep problems

A range of services for sleep problems can be accessed through the NHS. Your GP can tell you more about this.

Professor Gringras says: “Your doctor will also be able to give you basic advice on addressing sleep issues and, where appropriate, recommend a sleep clinic.”

Find your local NHS sleep medicine services.

For more advice, see Sleeping tips for teenagers.