The social media website Facebook has announced a new function for groups to share information.

The website, which has more than 900m active users, has launched a new function that members of group pages can see which other users have seen updates.

A spokesperson said: "The new groups feature acts like a read receipt. When you visit a group, you can view who’s seen each post. This way you can stay updated on the group’s activity. For example, in your football group you can post the new practice time and then see who got the update."

The number of people who have become digitally dependent is estimated by psychiatrists to have risen 30 per cent over the past three years. The Capio Nightingale Hospital in Marylebone, North London, launched a technology-addiction service two years ago and has seen a 15 per cent rise in patients over the past 12 months.

Psychiatrist Dr Nerina Ramlakhan, author of Tired But Wired, also works with law firms and investment banks across London. She has seen a 30 per cent rise in people suffering from digital dependency over the past three years, and has helped MPs, footballers and actors, as well as lawyers and investment bankers. "People are getting locked into a cycle of technology at work, and then surf the Net or use Facebook to unwind," she said. "They become exhausted, but cannot switch their brains off."