jean twenge, great to have you back on the "newshour".o as we heard today, a lot of concern on capitol hill expressed about the potential for these platforms to be causing harm to young people. what do we know about the actual research as to whether or not these things do cause harm? >> yeah, so, generally speaking, the more time a kid or a teen spends in front of a screen, the more likely they are to be depressed, anxious to harm themselves. there's gradations to this. watching videos is strong -- isn't as strongly linked to depression as, say, being on social media, but especially when kids and teens spend a lot of time online, it leaves less time for sleep, it leaves less time for interacting with people face-to-face, leaves less time for running around outside and exercising, and, so, perhaps, as a result, what we've seen is a huge increase in teen depression right at the time of these platforms became very popular. >> reporter: so do you feel that that -- is this causal or is this a correlation? i mean, do you feel confident that it'

for more on how these platforms are affecting kids' mental health, we turn to jean twenge.s a professor of psychology at san diego state university and the author of "i-gen: why today's super-connected kids are growing up less rebellious, more tolerant, less happy--and completely unprepared for adulthood." great to have you back on the "newshour." as we heard, a lot of concern on capitol hill expressed about the potential for these platforms to be causing harm in young people. what do we know about the actual research as to if these things do cause harm? >> generally speaking, the more time a kid or teen spends in front of the screen, the more likely they are to be depressed, anxious, to harm themselves. there's gradations to this. watching videos is not as strongly linked as being on social media. but when kids spend a lot of time online, it leaves less time sleep, less time for interacting with people face-to-face, less time for running around outside and exercising. perhaps as a result, what we have seen is a huge increase in teen depression right at the time these platf