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Teens are less happy and less satisfied with their lives than they were just five years ago. The question is: Why?

In a recent paper and in my book, iGen, we tried to answer this question using two types of evidence. First, we examined the time sequence of cultural changes over that same time (primarily 2011-2015), finding that teens’ well-being dropped suddenly around the time smartphones became common (2011-2012). Second, we examined correlations between teens’ time use and . We focused on activities that varied in popularity over time and could be easily categorized as screen versus non-screen. For example, iGen teens (those born after 1995) spend less time with their friends in person and attending religious services, and more time online. Within this list of activities, we found every screen activity was correlated with less happiness, and every non-screen activity was correlated with more happiness.

But that left unanswered another interesting question: What are the correlations between happiness and activities that were fairly constant over the years, or that couldn’t be clearly categorized as screen activities or non-screen activities? It might be interesting to take a more comprehensive look at activities and happiness. [NOTE: The following is not meant to be a test of hypotheses; it speculates post-hoc about why some activities correlate with happiness and some do not].

Here are the results from the nationally representative Monitoring the Future survey 2013-2016 for 8th and 10th graders’ self-reported happiness, controlled for race, , mother’s , and grade level. This list, more comprehensive than what we examined in the paper, is categorized into activities that teens usually do on their phones (red bars) and those they usually do without their phones (green bars). This is a little different from screen versus non-screen activities, but there’s a good amount of overlap. (The categorizations also aren't precise by any means — for example, "leisure time alone" doesn't necessarily involve phones or devices, but for iGen it often does, and "print media" such as magazines are sometimes read on phones.)

Source: Jean Twenge

The pattern is again clear: Nearly all phone activities are linked to less happiness, and nearly all non-phone activities are linked to more happiness. There are two exceptions, both correlations |.01| or under: TV (sometimes non-phone, sometimes phone) is linked to slightly less happiness, and working at a paid job (usually non-phone) does not correlate with happiness (r = .00). An activity not involving phones but that still involves screens, video arcades, correlates .03 with happiness (though I’m not sure most teens even know what a video arcade is anymore, and going to an arcade is usually a social activity).

Take a look at the bottom of the chart: Listening to music shows the strongest correlation with unhappiness. That may seem strange at first, but consider how most teens listen to music these days: on their phones, with earbuds firmly in place. Although listening to music is not per se, it is a phone activity for the vast majority of teens. Teens who spend hours listening to music are often shutting out the world, effectively isolating themselves in a cocoon of sound.

If you’re not iGen, you might still think of “listening to music” as playing the radio in the car, listening to CDs with friends, or showing off your stereo to your crush. But it’s not 1977 (or even 1997) anymore, and listening to music no longer means inviting your friends over to listen to the new Eagles LP or Nirvana CD. Instead, it often means a teen who has shut himself in his room or used her earbuds as an armor against social interaction. Earbuds are by far the most effective technique to nonverbally communicate the message: “Do not try to talk to me.”

The strongest correlation with happiness is sleep — teens who say they get more than seven hours of sleep more nights are happier. This makes sense, of course: Sleep deprivation is a major risk factor for both physical and mental health issues. Unfortunately, today's teens sleep less than teens once did, possibly due to spending more time on their phones and other devices.

There’s another way to look at this chart — with the exception of sleep, activities that usually involve being with other people are the most strongly correlated with happiness, and those that involve being alone are the most strongly correlated with unhappiness. That might be why listening to music, which most teens do alone, is linked to unhappiness, while going to music concerts, which is done with other people, is linked to happiness. It’s not the music that’s linked to unhappiness; it’s the way it’s enjoyed. There are a few gray areas here. Talking on a cell phone and using video chat are linked to less happiness — perhaps because talking on the phone, although social connection, is not as satisfying as actually being with others, or because they are a phone activities even though they are not, strictly speaking, screen time. Working, usually done with others, is a wash, perhaps because most of the jobs teens have are not particularly fulfilling.

Because this analysis is correlational, we can’t tell if these activities cause happiness, happiness causes teens to engage in these activities more, or if the same type of teens do both. The demographic controls partially address the third possibility. Other studies using longitudinal and experimental designs suggest that some, and perhaps most, of the causation goes from phone activities (social media time, online time) to unhappiness, rather than unhappiness leading to social media or online time. These studies look at the same people over time or randomly assign people to conditions, helping to rule out third variables.

This more comprehensive list of activities and their links to happiness provides more nuanced results than the shorter list, but the basic conclusion is still the same: Activities that involve being with others face-to-face (social interaction, religious services, volunteer work, and even going to movies) are linked to more happiness, and those that involve being alone or on your phone (social media, internet, listening to music, being alone) are linked to less happiness. In other words: If you’re looking for happiness, spend more time with people and less time with your phone.