Facebook could be making society miserable.
Pyschologists say the social network - used by more than 24 million British people a day - is strongly associated with declines in well-being, psychologists claim.
Scientists found the more time people spent on Facebook over a two-week period, the worse they subsequently felt.
In contrast, talking to friends on the phone or meeting them in person led to greater levels of happiness.
Study leader Dr Ethan Kross, from the University of Michigan in the US, said:
"On the surface, Facebook provides an invaluable resource for fulfilling the basic human need for social connection.
"But rather than enhance well-being, we found that Facebook use predicts the opposite result - it undermines it."
The researchers recruited 82 young adults, all of whom had smartphones and Facebook accounts.
To assess their personal levels of well-being, participants were sent questions by text message at five random times each day for two weeks.
The "experience sampling" technique is a recognised reliable way of measuring how people think, feel and behave in their day-to-day lives.
Participants were asked how they felt "right now", how worried or lonely they were, and to what extent they had been using Facebook or interacting with other people directly.
Writing in the online journal Public Library of Science ONE, the researchers said higher levels of Facebook use correlated with greater loss of well-being.
Volunteers were also asked to rate their level of life satisfaction at the start and end of the study.
Over the two-week period, satisfaction ratings were found to decline the more people used Facebook.
"This is a result of critical importance because it goes to the very heart of the influence that social networks may have on people's lives," said University of Michigan neuroscientist and co-author Dr John Jonides.
There was no evidence that people were more likely to log into Facebook when they felt bad, said the researchers.
In addition loneliness and Facebook both had an independent impact on happiness.
"It was not the case that Facebook use served as a proxy for feeling bad or lonely," said Dr Kross.
Further research is planned to look at the psychological reasons for the negative effect of Facebook on well-being.
Apple Macbook Air 13 Inch
<a href="http://www.apple.com/uk/" target="_blank">A light but powerful compromise</a> between the heavier-duty Macbook Pro, the new 13-inch Macbook Air has an incredible 12-hour battery, a new Intel Haswell chip and is just as light and portable as ever. A stunning machine.
Google Chromebook Pixel
<a href="http://www.google.com/intl/en_uk/chrome/devices/chromebook-pixel/" target="_blank">Google's ChromeBook Pixel</a> has the best screen we've ever seen on a laptop - and features stunning hardware design. It only runs the browser-based Chrome OS, however, and as such is severely limited in what it can actually do. But for the right kind of user, it's a wonderful machine.
Apple Macbook Pro 15-Inch With Retina Display
The Macbook with Retina display is just a beautiful, capable machine in every respect. WIth its elegant OS X software, stunning looks and lightweight, portable design, <a href="http://store.apple.com/uk/buy-mac/macbook-pro" target="_blank">it's an all-around classic.</a>
Samsung Series 7 Ultra
Samsung makes thin, beautiful, hard-wearing laptops, and this is no exception. It has an i% chip , a brilliant 1080P touchscreen and runs the always-improving Windows 8.1 OS. It starts at £1,000 and if you want a Windows machine at the same price-point as a Macbook Air, it's a good place to start.
Lenovo IdeaPad Yoga 13-inch
<a href="http://www.laptopmag.com/review/laptops/lenovo-ideapad-yoga.aspx#review">Laptop Magazine said</a> "the IdeaPad Yoga is an able contortionist, blurring the line between laptop and tablet, while enabling users to explore the full capabilities of Windows 8". We agree. With a bright touchscreen, an 180-degree rotating display and an all-important sturdy hinge, it's a decent bridge between tablet and laptop.
HP Chromebook 11
Like the bigger, and much more expensive Pixel, the Chromebook 11 only runs Google's very limited browser-based OS. But it also costs just £229, has a genuinely excellent screen and keyboard, and charges via MiniUSB rather than a traditional laptop charger. It's a storming machine for the price, as long as you're able to live within Google's walled garden.
ACER Aspire S7
The S7 is the same weight as the Macbook Air, has a great 1920 x 1080 pixels (touch) screen and is actually a little thinner than Apple's signature laptop. It has a lower-quality battery, though, and while it's cheaper by about £60 you might want to make sure Windows is that crucial for your workflow before making your choice.
For gamers you can't go far wrong with the <a href="http://www.dell.com/uk/p/alienware-17/pd?ST=alienware%20m17x&dgc=ST&cid=41141&lid=1069630&acd=239715600820560" target="_blank">Alienware M17x</a>. It's hefty, yes - you're not going to want to carry this around on the Tube too often. But it has a brilliant graphics card, as you'd expect, a 1080p 17-inch screen and runs an Intel Core i7. (Starts at around £1315)
Sony Vaio Pro
Sony's Vaio Pro line-up has all the basic high-quality features you want: they're light and thin, with decent battery life and excellent displays. They also have Sony's trademark black-ninja design and a few decent extras. They're not perfect - <a href="http://www.theverge.com/2013/6/4/4395926/sony-vaio-pro-review-were-going-to-war-with-the-macbook-air" target="_blank">The Verge notes they tend to feel a bit "flexible" in the middle</a> - but they're an excellent pro laptop range.