Excessive use has been tied to sleeplessness, depression and even reduced fertility. It can be both a social crutch and a destroyer of intimacy.
If you feel like you can't live without your handset, here are 8 good reasons to cut back on how much you use it:
grinvalds via Getty ImagesSex loses some of its heat when there's a smartphone between the sheets. Texts from your mom, tweets about Justin Bieber, breaking news notifications from HuffPost -- they don't exactly set the mood.
And yet, 20 percent of young adults report having used their phones during sex, according to a survey from market research firm Harris Interactive.
OcusFocus via Getty ImagesThe blue light streaming out of your phone can seriously damage your sleep. That's because blue light activates the area in the human brain that suppresses melatonin, which helps induce drowsiness.
If you want to snooze more soundly and feel more alert during the day, shut off your smartphone and other devices at least an hour before going to bed, experts suggest.
Michael Krinke via Getty ImagesPeering at your smartphone while driving is tempting, but dangerous. Nearly 50 percent of Americans admit to texting and driving, even though most people think it's a bad idea.
And it is bad. Every day nine people die in car accidents related to smartphone use.
Dean Belcher via Getty ImagesIf you've ever lost your smartphone, you've probably felt pangs of withdrawal.
Separating from your device can induce what some researchers have called "nomophobia," the fear of "losing the connectedness that smartphones allow." That fear can, in turn, cause people to cling to their phones in a way that resembles addiction.
lzf via Getty ImagesPeople who constantly check their smartphones tend to experience greater levels of depression and anxiety, according to a study from psychologists at the University of Illinois at Urbana-Champlain. This might be because people struggling with depression use their phones as a kind of escape.
"It appears that people who use cell phones to avoid stress and negative events in their real life also tend to have mental health problems," Dr. Alejandro Lleras, a psychologist at the university and the study's lead author, told HuffPost.
JGI/Tom Grill via Getty ImagesConstantly staring your smartphone screen can tear you away from the action around you. When you're on your phone, you're not really "there." That's why it can be such a joy to put away your handset and just revel in the moment, says Dr. Danny Penman, co-author of Mindfulness: Finding Peace In A Frantic World.
"If you are not the one calling the shots, mobile tech can easily take over your life and leave you burnt out and broken," Penman told HuffPost UK.
As an experiment, HuffPost Tech editor Damon Beres disabled notifications on all of his devices for a week. He found that doing so allowed him to relax more and finish a book he'd been chipping away at.
Maskot via Getty ImagesSmartphones can be an incredible resource for students. But they can also make it hard to concentrate. A study from Rice University found that using smartphones in the classroom made learning more difficult.
"Because smartphones are always on, they lead to interruptions when the students are studying/reading/preparing," Dr. Philip Kortum, the study's lead author and a faculty member in the psychology department at Rice University in Texas, told HuffPost.
If you really want to absorb information, it might be best to shut down your phone.
Babycakes RomeroSo many of us whip out our phones when a conversation drops off or a crowded elevator feels too quiet. But that impulse can prevent people from connecting with each other, in the view of photographer Babyface Romero, who in 2014 published a photo collection documenting smartphone use.
"It is sad that this technology which was supposed to connect people is making them disconnect from each other in person," Romero told HuffPost.