Madonna does not want her younger children living in a material world with their noses glued to smartphones.

Speaking to British Vogue, Madonna said she has imposed stricter smartphone rules for her younger children. The singer, actress, producer, director and mother of six told the magazine that she hasn’t yet allowed her 13-year-old son David to have his own smartphone. She said that the devices have an adverse effect on children and change the way they relate to the world.

“ ‘I made a mistake when I gave my older children phones when they were 13. It ended my relationship with them, really. Not completely, but it became a very, very big part of their lives.’ ” — —Madonna

“I made a mistake when I gave my older children phones when they were 13,” Madonna, 60, told the fashion magazine. “It ended my relationship with them, really. Not completely, but it became a very, very big part of their lives. They became too inundated with imagery and started to compare themselves to other people, and that’s really bad for self-growth.”

Chief among the effects: Smartphones may actually change children’s brains. The National Institutes of Health is in the midst of a $300 million study that’s following 11,000 children over 10 years. It already has some preliminary results: MRI scans from 4,500 participants show physical changes in the brains of those children that use smartphones for more than 7 hours per day.

Those changes include thinning of the brain’s cortex, which is associated with lower IQ. Children who spend just 2 hours a day on their smartphones also have lower language and thinking skills. Dimitri Christakis, one of the author’s of screen guidelines from the American Academy of Pediatrics and a lead author for its Virtual Violence policy, told CBS, “We’re sort of in the midst of a natural kind of uncontrolled experiment.”

Smartphones are synonymous with apps like Snapchat SNAP, -3.39% , Facebook FB, +0.20% and Instagram. A 2015 study in the journal Cyberpsychology, Behavior and Social Networking suggested that young people who are heavy users of social media — spending more than 2 hours a day on these apps — are also more likely to report poor mental health symptoms.

Madonna may also be wise to forbid her teenage son from owning a smartphone. Teens suffering from depression or anxiety often use smartphones as a coping skill rather than learning to sit with their emotions, process their feelings and develop relationships, according to Cole Rucker, co-founder of Paradigm Malibu, an adolescent mental health and drug abuse treatment center.

“ Teens suffering from depression or anxiety often use smartphones as a coping skill rather than learning to sit with their emotions, process their feelings and develop relationships. ”

Almost half (45%) of kids older than 6 have access their own mobile device, a study released last year by Common Sense Media, a San Francisco-based organization that examines the impact of technology and media on families, concluded. “What clearly has changed is how young people access and view TV shows, videos and games,” it found. But they are now devoting hours to them.

Just 4% of screen time was mobile versus one-third of screen time in 2018, the study added. Children spend an average of 48 minutes per day on their smartphones and tablets, up from 5 minutes a day in 2011. The American Academy of Pediatrics recommends that children between the ages of 2 and 5 should get no more than one hour of any kind of screen time per day.

Of course, children learn by example. Parents with kids aged 8 to 18 years of age spend over 9 hours with screen media daily between work and home, according to “Plugged-In Parents of Tweens and Teens,” a survey of 1,700 such parents by Common Sense Media. Child psychologists say relationships suffer when parents spend time on their smartphones while they’re with their kids.

Tweens spend over 4.5 hours on screen media on average every day and 6.5 hours spent by teens every day, a similar poll of more than 2,650 children by the organization found. “We hope that taking an honest look at how parents use media and tech, how they manage and monitor their kids,” said Michael Robb, director of research at Common Sense Media.