How many hours a day do you spend on Facebook? How about texting friends? Reading magazines? If you're a millennial, it may be more time than you think. New research by social-influence marketing platform Crowdtap indicates that individuals ages 18 to 36 spend an average of 17.8 hours a day with different types of media.

Those hours represent a total across multiple media sources, some of which are consumed simultaneously. For example, a twenty-something may report spending two hours a day on Facebook, an hour a day answering texts and three hours a day watching television, which would count as six hours total, but may only be three "real" hours of her day if she does some of those things at the same time.

"Millennials are always on," says Anna Kassoway, Crowdtap's chief marketing officer. "Some of it is passive consumption. A lot is media hours that are overlapping."

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Some forms of media are more important to millennials than others. Social media is a top priority, as 71 percent say that they engage in social media daily. User-generated content -- which encompasses social-media posts, photos, blogs, email, texting and talking to others about media -- occupies about 5.4 hours of the average millennial's day. That's 30 percent of their total daily media consumption.

The only rival to user-generated media is the old standby of traditional media -- print, radio and television – which accounts for 33 percent of millennials' media consumption.

Traditional forms of media may take up more of millennials' time, but user-generated content shapes millennials' lives more than any other form of media. Information gathered through user-generated content is trusted 40 percent more than information from other media – including newspapers and magazines. Millennials also find user-generated content 30 percent more memorable than other sources.

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What this research means for brands is important. Today, most companies spend their marketing budgets, even those geared toward social media, primarily on sending out advertising messages. Kassoway predicts that brands will increasingly rely on "influencers": consumers who shape their peers' perceptions through user generated content. Madewell's #Flashtagram, for example, resulted in 500 Madewell employees, bloggers and fashion magazine editors posting their best denim shots on Instagram, gathering more than 160,000 likes in one day and 8.50 million impressions in total.

"The best social marketing is not publishing itself, but inspiring others to publish content about them," says Kassoway.

As millennials are increasingly tapped into media, the question isn't whether they'll hear a brand's message, but if they'll listen.

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