As American students and workers spend more time on the Internet and on social media sites in particular, their levels of productivity are tanking. The average college student might spend three hours checking their various social media sites, but only two hours studying. That discrepancy is reflected in lower GPAs. Workers aren’t faring much better, either. Every time someone at work gets an IM, a Facebook message or a tweet, it takes them a whopping 23 minutes to get back on task. Taken all together, that costs the American economy $650 billion per year in lost productivity. The next time you think about checking a social media site, consider how much time and energy it will actually take.