The results were striking: individuals who completed these tasks while their phones were in another room performed the best, followed by those who left their phones in their pockets. In last place were those whose phones were on their desks. We saw similar results when participants’ phones were turned off: people performed worst when their phones were nearby, and best when they were away in a separate room. Thus, merely having their smartphones out on the desk led to a small but statistically significant impairment of individuals’ cognitive capacity—on par with effects of lacking sleep.