The whole point of a smartphone is to make you more productive. Sure, your little gadget may lure you into the occasional round of Candy Crush or entice you to check friends' Facebook statuses compulsively, but as a business owner, the heart of the matter is that being always connected allows you to work wherever, whenever, and squeeze a few extra hours of productivity out of the day.

But what if, despite the apparent advantages of sending those last couple of emails before you fall asleep at night, your end-of-the-day smartphone use, on balance, actually means you get less done?

Your Little Insomnia Machine

That's what a pair of new studies out of Michigan State University implies. Led by management professor Russell Johnson, the research looked at smartphone use both among upper-level managers and a variety of mid-level professionals, like nurses and accountants, asking them to both report their nighttime smartphone use and then answer questions about their levels of alertness and productivity the next day.

What did the studies find? Using a smartphones before bed resulted in less sleep and less energy at work the next day. The researchers also determined that smartphones had more of a negative effect on alertness than watching television or using a laptop. Why? It seems smartphones offer a sleep-busting double whammy: both keeping the brain psychologically engaged and emitting "blue light" that inhibits our bodies' ability to relax into sleep.

"Smartphones are almost perfectly designed to disrupt sleep because they keep us mentally engaged late into the evening, they make it hard to detach from work so we can relax and fall asleep," Johnson commented.

Other Reasons to Quit

Scientific confirmation that spending time with your smartphones late at night is contributing to a national epidemic of undersleep might be the final nail in the coffin for your evening email or text habit, but Johnson is hardly the first to urge entrepreneurs and others to put down their phones in the evenings. Writing for The New Yorker, James Surowiecki recently summarized the emerging consensus, even among famously hard-charging bankers, that long hours and overwork are actually taking a bite out of our productivity (and sanity). Others have argued the same.

But beyond the arguments centered on productivity and creativity, there are also those who note being constantly plugged in to the minutiae of day-to-day business is killing our ability to reflect and think big picture.  

Are you guilty of late night smartphone use?