A recent study from Oxford University has found there's actually a sweet spot in terms of digital screen use for teenagers.

The researchers' 'Goldilocks hypothesis' argues that four hours 17 minutes a day on computers will allow adolescents to reap rewards, primarily better social skills and support, without impacting their wellbeing.

That's not the full story, however, warns sleep expert Dave Gibson, co-author of The Art Of Falling Asleep: "Sadly, from my point of view, this study totally ignores all previous research, which shows that time spent on screens, especially at night, has a detrimental effect on teenagers' sleep.

"A study of 10,000 teenagers in Norway in 2015 showed that those who used a computer in the hour before bed were three times more likely to get less than five hours sleep. "The study also showed that more than four hours of daytime screen time use meant a 49 per cent greater risk of taking longer than 60 minutes to fall asleep."

Plus, Gibson warns, the blue light emitted by screens prevents teens from nodding off promptly and getting the requisite eight to ten hours sleep a night. "Blue light acts like the morning sunlight, which wakes us up by switching off the melatonin (the sleep hormone) production in the brain. This is the opposite desired effect for the evening time, as to help us sleep, melatonin needs to be switched on in the dark," Gibson says.

Top tips to ensure teens get a good night's rest without ditching their devices altogether:

Put all devices to bed at least one hour before they go to bed

Take phones out of the bedroom before bedtime. In an ideal world, we would have no technology (including mobile phones) in the bedroom whatsoever.

Reduce blue light. Dim computer screens or wear glasses that block out blue light. Install a blue light filtering system such as flux (justgetflux.com) on computers and electronic devices to reduce blue light and always use the night-time mode on devices.

Give teenagers the facts about how screen time stimulation and blue light late at night will both prevent getting to sleep easily and reduce the amount of overall sleep.