Health experts love to say that sitting is the new smoking. Given the number of diseases to which sitting is linked, and the number of people it apparently kills every year, sitting is one of the worst things we can do for health. But possibly as concerning is the mental health habit that’s almost ubiquitous these days: Mindlessly scrolling through our social media feeds when we have a few spare minutes (or for some, hours). And as we probably know intuitively, and as the research is confirming, it’s not the best habit when it comes to our collective psychology.

The American Academy of Pediatrics has warned about the potential for negative effects of social media in young kids and teens, including cyber-bullying and “Facebook depression.” But the same risks may be true for adults, across generations. Here’s a quick run-down of the studies that have shown that social media isn’t very good for mental well-being, and in some ways, it can be pretty bad.

It’s addictive

Experts have not been in total agreement on whether internet addiction is a real thing, let alone social media addiction, but there’s some good evidence that both may exist. A review study from Nottingham Trent University looked back over earlier research on the psychological characteristics, personality and social media use. The authors conclude that “it may be plausible to speak specifically of ‘Facebook Addiction Disorder’…because addiction criteria, such as neglect of personal life, mental preoccupation, escapism, mood modifying experiences, tolerance and concealing the addictive behavior, appear to be present in some people who use [social networks] excessively.” (They also found that the motivation for people’s excessive use of social networks differs depending on certain traits—introverts and extroverts use it for different reasons, as do people with narcissistic traits. But that deserves a piece of its own.)

And studies have confirmed that people tend to undergo a kind of withdrawal: A study a few years ago from Swansea University found that people experienced the psychological symptoms of withdrawal when they stopped using (this went for all internet use, not just social media). Their recent follow-up study found that when people stop using, they also undergo small but measurable physiological effects. Study author Phil Reed said, “We have known for some time that people who are over-dependent on digital devices report feelings of anxiety when they are stopped from using them, but now we can see that these psychological effects are accompanied by actual physiological changes.” Whether this is true of social media per se is unclear right now, but anecdotal evidence suggests it may be.

It triggers more sadness, less well-being

The more we use social media, the less happy we seem to be. One study a few years ago found that Facebook use was linked to both less moment-to-moment happiness and less life satisfaction—the more people used Facebook in a day, the more these two variables dropped off. The authors suggest this may have to do with the fact that Facebook conjures up a perception of social isolation, in a way that other solitary activities don’t. “On the surface,” the authors write, “Facebook provides an invaluable resource for fulfilling such needs by allowing people to instantly connect. Rather than enhancing well-being, as frequent interactions with supportive ‘offline’ social networks powerfully do, the current findings demonstrate that interacting with Facebook may predict the opposite result for young adults—it may undermine it.”

In fact, another study found that social media use is linked to greater feelings of social isolation. The team looked at how much people used 11 social media sites, including Facebook, Twitter, Google+, YouTube, LinkedIn, Instagram, Pinterest, Tumblr, Vine, Snapchat and Reddit, and correlated this with their “perceived social isolation.” Not surprisingly, it turned out that the more time people spent on these sites, the more socially isolated they perceived themselves to be. And perceived social isolation is one of the worst things for us, mentally and physically.

Comparing our lives with others is mentally unhealthy

Part of the reason Facebook makes people feel socially isolated (even though they may not actually be) is the comparison factor. We fall into the trap of comparing ourselves to others as we scroll through our feeds, and make judgements about how we measure up. One study looked at how we make comparisons to others posts, in “upward” or “downward” directions—that is, feeling that we’re either better or worse off than our friends. It turned out that both types of comparisons made people feel worse, which is surprising, since in real life, only upward comparisons (feeling another person has it better than you) makes people feel bad. But in the social network world, it seems that any kind of comparison is linked to depressive symptoms.

It can lead to jealousy—and a vicious cycle

It’s no secret that the comparison factor in social media leads to jealousy—most people will admit that seeing other people’s tropical vacations and perfectly behaved kids is envy-inducing. Studies have certainly shown that social media use triggers feelings of jealousy. The authors of one study, looking at jealousy and other negative feelings while using Facebook, wrote that “This magnitude of envy incidents taking place on FB alone is astounding, providing evidence that FB offers a breeding ground for invidious feelings.” They add that it can become a vicious cycle: feeling jealous can make a person want to make his or her own life look better, and post jealousy-inducing posts of their own, in an endless circle of one-upping and feeling jealous.

Another study looked at the connection between envy and depression in Facebook use and, interestingly, discovered that envy mediates the Facebook-depression link. That is, when envy is controlled for, Facebook isn’t so depressing. So it may be the envy that’s largely to blame in the depression-Facebook connection.

We get caught in the delusion of thinking it will help

Part of the unhealthy cycle is that we keep coming back to social media, even though it doesn’t make us feel very good. This is probably because of what’s known as a forecasting error: Like a drug, we think getting a fix will help, but it actually makes us feel worse, which comes down to an error in our ability to predict our own response. One study looked at how people feel after using Facebook and how they think they’ll feel going in. Like other studies suggested, the participants in this one almost always felt worse after using it, compared to people engaging in other activities. But a follow-up experiment showed that people generally believed that they’d feel better after using, not worse. Which of course turns out not to be the case at all, and sounds a lot like the pattern in other types of addiction.

More friends on social doesn’t mean you’re more social

A couple of years ago, a study found that more friends on social media doesn’t necessarily mean you have a better social life—there seems to be a cap on the number of friends a person’s brain can handle, and it takes actual social interaction (not virtual) to keep up these friendships. So feeling like you’re being social by being on Facebook doesn’t work. Since loneliness is linked to myriad health and mental health problems (including early death), getting real social support is important. Virtual friend time doesn’t have the therapeutic effect as time with real friends.

All of this is not to say that there’s no benefit to social media—obviously it keeps us connected across great distances, and helps us find people we’d lost touch with years ago. But getting on social when you have some time to kill, or, worse, need an emotional lift, is very likely a bad idea. And studies have found that taking a break from Facebook helps boost psychological well-being. If you’re feeling brave, try taking a little break, and see how it goes. And if you’re going to keep “using,” then at least try to use in moderation.