It’s interesting how studies on the negative effects of social media on mental health are mixed: some find an effect, some don’t (or only find a very small effect). Some take this as proof that social media is actually fine for mental health.
My hypothesis is different. I think that the effects of social media are extremely heterogeneous based on app, population, and dosage: that in some subgroups, some social media apps (when used in high doses) have substantially negative effects on mental health, but in other subgroups, using other social media apps in moderate doses has no negative effect on mental health.
For instance, 13-year-old girls in the US using TikTok or Instagram for 4 hours a day may be very differently impacted than 25-year-old men in Denmark using Twitter/X or WhatsApp for 30 minutes per day.
The current studies may be like trying to answer the generic question: “Do non-prescription drugs have a negative mental health effect?” This question can’t be answered because it combines too many dissimilar things. In particular, the answer hinges on which drugs we’re talking about (cannabis vs. fentanyl), the age of the person doing the drug (teenagers vs. adults), and the quantity of drug use (occasional vs. extreme usage).
If my hypothesis is true, then getting to the bottom of the true impacts of social media on mental health will require carefully designed studies that subdivide by app and by population (ideally after preliminary research is done to figure out what apps and which populations are reasonable to group together – for instance, it may be essential to segment by gender and rough age group and even by culture, but it’s important to get these segmentations right if the research is going to make progress).
Another thing that makes this research so tricky is that social media literally adapts itself to what you pay attention to. So if you tend to click on upsetting things, it will show you more upsetting things, which can create a self-reinforcing cycle, whereas if you click on things that are interesting and pleasant, you’ll get more of those instead. So even at the level of the individual, social media can provide highly varied experiences. It’s instructive to compare your social media feed to a friend’s (on the same app). When I’ve done this, it’s been remarkable to see just how different our experiences on that app are.
Overall, my best guess is that most people’s social media use would be found to have little or no negative causal link to mental health. But I would predict that there is a moderately sized causal negative link to mental health for:
- teenage girls scrolling Instagram a large amount (e.g., checking it >25 times daily)
- teenage boys playing video games (but not with friends), very large amounts (e.g., > 5 hours per day)
- people who are already predisposed to worry a lot about the state of the world, scrolling Twitter a large amount (e.g., > 3 hours daily)
- I also would predict a negative impact on attention or focus for those who use TikTok a lot (>5 hours daily)
- But I would predict little to no average negative mental health effects for apps that a person uses only 20 minutes per day or less, since I think that’s unlikely to be a high enough dose to cause problems for many people
Another hypothesis is that insofar as social media causes negative mental health impacts, it’s because it changes the situation for everyone at once. For instance, if all teenagers in a school are on social media, that can change the way that they socialize (or how much people socialize) and how they interact (e.g., how much bullying or social comparison occurs). By this view, studying what happens to individuals when they use more or less social media misses the important effects. If this is the case, it makes the phenomena even harder to study!
This piece was first written on August 29, 2025, and first appeared on my website on November 2, 2025.
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