Back when my daughter was a toddler, I would make a joke about my phone: "It's a drug for her," I'd say to my husband. "You can't even show it to her without causing a tantrum."

She had the same reaction to cupcakes and ice cream at birthday parties. And as she grew older, another craving set in: cartoons on my computer.

Every night, when it was time to turn off the screen and get ready for bed, I would hear an endless stream of "But Mamas." "But Mama, just five more minutes. But Mama, after this one show ... but Mama ... but Mama ... but Mama."

Given these intense reactions to screens and sweets, I assumed that my daughter loves them. Like, really loves them. I assumed that they brought her immense joy and pleasure. And thus, I felt really guilty about taking these pleasures away from her. (To be honest, I feel the same way about my own "addictions," like checking social media and email more than a hundred times a day. I do that because they give me pleasure, right?)

But what if those assumptions are wrong? What if my daughter's reactions aren't a sign of loving the activity or the food? And that, in fact, over time she may even come to dislike these activities despite her pleas to continue?

In the past few years, neuroscientists have started to better understand what's going on in kids' brains (and adult brains, too) while they're streaming cartoons, playing video games, scrolling through social media, and eating rich, sugar-laden foods. And that understanding offers powerful insights into how parents can better manage and limit these activities. Personally, I call the strategy "anti-dopamine parenting" because the ideas come from learning how to counter a tiny, powerful molecule that's essential to nearly everything we do.

Turns out, smartphones and sugary foods do have something in common with drugs: They trigger surges of a neurotransmitter deep inside your brain called dopamine. Although drugs cause much bigger spikes of dopamine than, say, social media or an ice cream cone, these smaller spikes still influence our behavior, especially in the long run. They shape our habits, our diets, our mental health and how we spend our free time. They can also cause much conflict between parents and children.

This is your child's brain on cartoons (or video games or cupcakes)

Dopamine is a part of an ancient neural pathway that's critical for keeping us alive. "These mechanisms evolved in our brain to draw us to things that are essential to our survival. So water, safety, social interactions, sex, food," says neuroscientist Anne-Noël Samaha at the University of Montreal.

For decades, scientists thought dopamine drew us to these vital needs by providing us with something that's not as critical: pleasure.

"There's this idea, especially in the popular media, that dopamine increases pleasure. That, when dopamine levels increase, you feel the sensation of 'liking' whatever you're doing and savoring this pleasure," Samaha says. Pop psychology has dubbed dopamine the "molecule of happiness."

But over the past decade, research indicates dopamine does not make you feel happy. "In fact, there's a lot of data to refute the idea that dopamine is mediating pleasure," says Samaha.

Instead, studies now show that dopamine primarily generates another feeling: desire. "Dopamine makes you want things," Samaha says. A surge of dopamine in your brain makes you seek out something, she explains. Or continue doing what you're doing. It's all about motivation.

And it goes even further: Dopamine tells your brain to pay particular attention to whatever triggers the surge.

It's alerting you to something important, Samaha says. "So you should stay here, close to this thing, because there's something here for you to learn. That's what dopamine does."

And here's the surprising part: You might not even like the activity that triggers the dopamine surge. It might not be pleasurable. "That's relatively irrelevant to dopamine," Samaha says.

In fact, studies show that over time, people can end up not liking the activities that trigger big surges in dopamine. "If you talk to people who spend a lot of time shopping online or, going through social media, they don't necessarily feel good after doing it," Samaha says. "In fact, there's a lot of evidence that it's quite the opposite, that you end up feeling worse after than before."

"A hijacked neural pathway"

What does this all mean for your kids? Say my daughter, who's now 7 years old, is watching cartoons after dinner. While she's staring into the technicolor images, her brain experiences spikes in dopamine, over and over again. Those spikes keep her watching (even if she's actually really tired and wants to go to bed).

Then I come into the room and say, "Time's up, Rosy. Close the app and get ready for bed." And although I'm ready for Rosy to quit watching, her brain isn't. It's telling her the opposite.

"The dopamine levels are still high," Samaha explains. "And what does dopamine do? It tells you something important is happening, and there's a need somewhere that you have to answer."

And what am I doing? I'm preventing her from fulfilling this need, which her brain may elevate as being critical to her survival. In other words, a neural pathway made to ensure humans go seek out water when they're thirsty is now being used to keep my 7-year-old watching yet another episode of a cartoon.

Not finishing this "critical" task can be incredibly frustrating for a kid, Samaha says, and "an agitation arises." The child may feel irritated, restless, possibly enraged.

Because the spike in dopamine holds a child's attention so strongly, parents are setting themselves up for a fight when they try to get them to do any other activity that triggers smaller spikes, such as helping parents clean up after dinner, finishing homework or playing outside.

"So I tell parents, 'It's not you versus your child, but rather it's you versus a hijacked neural pathway. It's the dopamine you're fighting. And that's not a fair fight,'" says Emily Cherkin, who spent more than a decade teaching middle school and now coaches parents about screens.

This response can happen to children at any age, even toddlers, says Dr. Anna Lembke, who's a psychiatrist at Stanford University and author of the book Dopamine Nation. "Absolutely. This happens at the earliest ages. So screens and sweets are, in and of themselves, alluring and potentially intoxicating."

Armed with this knowledge, parents have more power to reduce the stress and negative consequences of these dopamine-surging activities. Here are some strategies to do that.

Tip 1: Wait 5 minutes

Dopamine surges are potent, says neuroscientist Kent Berridge at the University of Michigan, but they are fast. "They have a short half-life," he says.

"If you take away the cue [triggering the dopamine] and you can wait two to five minutes, a lot of the urge usually goes away," says Berridge, who's been instrumental in deciphering dopamine's role in the brain.

In other words, when you stop the cartoons at 30 minutes or cut off the cake at one slice, you may hear a bunch of whining, protest and tears, but that reaction will likely be brief.

But here's the key. You have to put the dopamine trigger out of sight, says Lembke at Stanford. Because seeing the laptop or extra leftover cake can start the cycle of wanting over again.

Tip 2: Look for the "Goldilocks" activities

Of course, not all of these activities and foods will be as enticing or intoxicating to every child, Lembke explains. "Our brains are all wired a little bit differently from one individual to the next."

And remember, dopamine motivates children to act and stay focused. The key, she says, is to figure out which activities give your child the right amount of dopamine. Not too little and not too much — the Goldilocks amount. And to do that, she says, pay attention to how your kid feels after the activity stops.

"If the child feels even better after the activity, that means we're getting a healthy source of dopamine," Lembke says. Not too little. But also not too much. And there's low risk the activity will become problematic for the child.

For example, my daughter doesn't have (much of) a problem turning off audiobooks or putting away art projects. Same goes for video-calling with friends, coloring, reading and, of course, playing outside with friends. These activities make her behavior better afterward, not worse.

What about the opposite — when a child feels worse after an activity or snack, and their behavior declines? Then, Lembke says, there's a high risk that the activity could hook the child into a compulsive loop. "Once they start engaging often and for long periods of time, they may really lose control," she explains.

"People have this idea that, 'Oh, well, if I let my kid play as many video games as they want or be on social media as much as they want, they'll get tired of it.' And in fact, the opposite happens," Lembke says.

Research indicates that over time, some people's brains can actually become more sensitive to the dopamine triggered by a particular activity. And therefore, the more time a person spends engaged with this activity, the more they may crave it — even if the activity becomes unpleasurable.

So, Lembke says, parents really need to be careful and thoughtful with these activities. They need to limit the frequency and duration.

Which brings us to ...

Tip 3: Make microenvironments

Create places in your home where the child can't access or see problematic devices, Lembke recommends. For example, have only one room in the house where children can use the phone or tablet. Keep these devices out of bedrooms, the kitchen, the dining room and the car.

At the same time, create times in your schedule where the child cannot see or access this device. Narrow down usage to only a small time each day, if possible. Or take a weekly "tech Sabbath," where everyone in the family takes a 24-hour break from their phones and tablets.

And for problematic foods, keep them out of the house. For example, the family eats ice cream only on special trips to the ice cream parlor.

Lembke calls these "microenvironments" — both physical and chronological. And they can have profound power over our brains, she says. "It's amazing how when we know we can't go on a device, the craving goes away."

Because here's the tricky aspect of dopamine: Our brains can start to predict when dopamine spikes are imminent, Lembke explains. We identify signals in the environment that point to it. These environmental cues can actually trigger a surge of dopamine in the brain before the child even begins eating or using a screen. These spikes can be larger than the ones experienced during the activity.

For a child, a signal could be a tablet sitting on a shelf, walking into the living room where they usually use a device, or even simply the time of day.

These environmental signals can make it tough, even painful, for kids to start breaking their habits, Lembke says. But that pain usually dissipates in a few days or weeks. Give children time to adjust.

Tip 4: Try a habit makeover

Instead of cutting out an activity altogether, look for a version that's more purposeful, says neuroscientist Yevgenia Kozorovitskiy at Northwestern University.

Kozorovitskiy, who has two tween boys, ages 11 and 12, says prohibiting video games altogether isn't realistic for her family. But she does think carefully about which games they're playing. "They will sometimes want to play this adventure game that's really complex and cognitively wonderful," she explains. "It requires exploration, discovery and strategy. And they play it together, physically. They're speaking about strategy, exchanging plans and using advanced social and language skills."

I tried this strategy with my daughter. One night we switched the cartoons for a language learning app. I told her that having an activity that's more purposeful will actually be more pleasurable.

And yes, she expressed great disappointment in this swap out, with tears and "But Mamas." But I stayed strong and calm, and I waited. After a few minutes, just as Kent Berridge said, the craving seemed to pass even more quickly than I expected. She easily switched gears to learning a bit of Spanish each night — with very little fuss.

I also started to put in place a piece of advice I heard from all the experts: Enrich your child's life off the screens. We had a neighbor teach her how to crochet. As a family, we started going for more walks after dinner. We bought a new pet (or actually 15 new pets) for her to take care of. And we started having more friends over on the weekends.

And guess what happened? After using the language app for a few weeks, she lost interest in the screens altogether. She hasn't watched a cartoon since.

But I'll tell you this: I will think very carefully before introducing a new app, device or even a new dessert into our lives. The battle against dopamine is just too hard for me to fight.

Jane Greenhalgh edited the radio story; Diane Webber edited the digital story. contributed to this story

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