I AM so glad there was no social media when I was a teenager.

How I would have hated it, the constant in-your-face comparisons with the lives of my peer group.

I would also have struggled with the time it consumed, keeping up with the constant postings of others and updating your own.

Disturbingly, every day, before they go to bed, a fifth of adolescents in the UK are spending more than five hours on Facebook, Twitter, Instagram and other sites, a study discovered.

Examining the link between social media use and sleep, researchers at the University of Glasgow looked at figures from 11,872 youngsters aged between 13 and 15 and found that 20.8 per cent spent this inordinate amount of time online.

Teenagers on social media for long periods of time were found to be 68 per cent more likely not to go to sleep until after 11pm on a school night. They were more likely to have frequent night-time awakenings, the effects of which could take a toll on their day-to-day functioning and overall health.

But how do you prevent youngsters spending so much time online? Homework is set online, so it’s not as if they need to break away to do that. There has never been so much distraction.

This could not be further removed from how I spent my evenings at that age. After tea I’d get on with my homework - textbooks and pens only in those days. Then I would go out with other teenagers in the village. We’d do things that young people did in those days, walking round the village or sitting in the bus shelter looking mean and moody. A waste of time, some would say, but at least we got some fresh air and exercise before bed.

I’d go home and watch TV before going to bed at about 10pm.

I shared a bedroom with my sister, five years younger, so when I went to bed it had to be lights out. The only distraction came when I occasionally tuned in to Radio Luxembourg on my portable radio. It was turned down so low I could barely hear it. Most of the time I did not even know what I was listening to, but it was the ‘in’ thing to do in those days.

Occasionally I might read a book by torchlight, under the bedclothes, for ten minutes.

Other than by getting up and going downstairs to use the house phone, there was no way I could find out what my friends were up to (they would most likely be doing exactly the same thing).

Now teenagers chat with friends all evening, send texts, read about the Kardashians and admire selfies of each other.

Girls are more likely to spend a longer period of time checking their social media, said the study, with 28.4 per cent spending more than five hours on it compared to 13.7 per cent of boys.

The study found that spending an increased amount of time online was having a detrimental impact on young people’s health and education. Is there any wonder?

I know how hard is for parents. I once wrestled with my eldest daughter to take her phone away. I’d gone to the toilet in the early hours and seen the light from her phone flickering under her door. She had to get up for school and an ugly scene ensued as I attempted to remove it. Sadly, such phone-related disruption was common.

It’s a dangerous addiction for which there seems to be no cure. From next year, says the Government, lessons for schoolchildren will include learning about the importance of sleep and how it can affect health. It remains to be seen whether this will do any good.