If you’re a parent of young children living in the mobile internet era, it’s hard to resist not handing over a smartphone or a tablet to keep kids entertained when you really need them to be the sweet, quiet little angels you wish that they could be pretty much all the time. There are all sorts of great video and gaming apps designed for kids anyway, so why not?

It’s not the kid-friendly content you have to worry about – it’s the effect of excessive amounts of screen time your kids are being exposed to on a regular basis. The younger they are while their brains are developing rapidly, the more adverse the effects may be. According to the American Academy of Pediatrics, parents of infants and children under the age of two should avoid exposing them to smartphones, tablets, computers, televisions and anything else that serves to entertain people through a screen.

Children who are older may benefit from apps and mobile websites that promote learning, but there’s no question that frequent and prolonged use of mobile devices may create problems in normal, healthy development and everyday habits. Here are some of the things you need to be aware of if you’re a parent who lets their kids play with smartphones or tablets.

They contribute to sleep deprivation.

Any form of media that has a screen emits blue light that tends to mimic daylight in a way that confuses our internal body clocks. Both children and adults rely on their circadian rhythms to regulate their sleep cycles, but when their eyes are exposed to this blue light too late in the evening or at night, it sends a signal to the brain that it’s daytime and that it’s time to stay awake. One study found that infants and toddlers who watched TV were more likely to experience irregular sleep patterns.

If your child has trouble falling asleep or staying asleep, make sure you enforce a strict cut-off time for smartphones and other media anywhere from 1 to 3 hours before bedtime. Instead, use this time to read a book to your child or have them read it to you aloud.

They promote sedentary behavior, which contributes to obesity.

Using a smartphone, a tablet or any other form of screen media generally requires a lot of sitting in order to pay attention to it. All children are energetic and have a natural urge to run, jump, skip, climb, dance and play, which helps them develop a strong and healthy heart, lungs, bones, muscles and brain. The Center for Disease Control and Prevention says that children and adolescents require a minimum of one hour of physical activity every day, and that one-hour minimum should involve moderate-intensity to vigorous-intensity activity.

To keep your kids from spending excessive amounts of time hanging around the house with nothing to do but sit around and entertain themselves with mobile devices, try enrolling them in extra-curricular activities like gymnastics, swimming, baseball or soccer to encourage them to get moving. Or to save some money, you could even just make a habit out of taking regular trips to the park, setting up a swing set in the backyard, scheduling regular play dates with friends or getting your kids to help out with chores around the house.

They can cause eye discomfort.

Although it’s not currently yet known whether staring at screens for long periods of time can cause any permanent damage to the eyes, it certainly is known to cause discomfort. Both children and adults can experience it, but children may be more susceptible to developing symptoms depending on the unique ways that they use their devices. Commonly referred to as “digital eye strain,” symptoms usually include pain, fatigue, blurred vision, headaches and dry eyes.

If your child has trouble falling asleep or staying asleep, make sure you enforce a strict cut-off time for smartphones and other media anywhere from 1 to 3 hours before bedtime. Instead, use this time to read a book to your child or have them read it to you aloud.

They promote sedentary behavior, which contributes to obesity.

Using a smartphone, a tablet or any other form of screen media generally requires a lot of sitting in order to pay attention to it. All children are energetic and have a natural urge to run, jump, skip, climb, dance and play, which helps them develop a strong and healthy heart, lungs, bones, muscles and brain. The Center for Disease Control and Prevention says that children and adolescents require a minimum of one hour of physical activity every day, and that one-hour minimum should involve moderate-intensity to vigorous-intensity activity.

To keep your kids from spending excessive amounts of time hanging around the house with nothing to do but sit around and entertain themselves with mobile devices, try enrolling them in extra-curricular activities like gymnastics, swimming, baseball or soccer to encourage them to get moving. Or to save some money, you could even just make a habit out of taking regular trips to the park, setting up a swing set in the backyard, scheduling regular play dates with friends or getting your kids to help out with chores around the house.

They can cause eye discomfort.

Although it’s not currently yet known whether staring at screens for long periods of time can cause any permanent damage to the eyes, it certainly is known to cause discomfort. Both children and adults can experience it, but children may be more susceptible to developing symptoms depending on the unique ways that they use their devices. Commonly referred to as “digital eye strain,” symptoms usually include pain, fatigue, blurred vision, headaches and dry eyes.

In addition to simply reducing the amount of time that kids spend looking at the screens of smartphones and other electronics devices, parents should take care to schedule annual eye examinations for their kids, teach them to position devices at an appropriate distance from their faces when using them, adjust the brightness of devices and instruct them to take breaks every 10 to 20 minutes that they’ve been staring at devices.

They can cause aches and pains in the neck, shoulders, back, hands, thumbs and other parts of the body.

Smartphone use forces people to tilt their heads down to look at them while moving their wrists and fingers in unnatural ways. Doing this frequently and for prolonged periods can cause pain and even permanent damage to bones and joints in the upper part of the body – especially the neck and spine. According to one leading Australian chiropractor interviewed by The Daily Mail Australia, an increasing number of children and teens are becoming hunchbacks because of their smartphone addictions.

The damage can be worsened by a sedentary lifestyle, so parents should encourage their kids to take frequent breaks and get physically active on a daily basis. It’s also worth talking to kids about the importance of proper body positioning when using their mobile devices and showing them how to lift their devices up higher to promote a more straightforward gaze. Parents can even just tell their kids to use their eyes to focus their gaze downward at the screen as a simple solution to minimizing the need to tilt their heads so much.

They may contribute to shortened attention spans.

Less than 5 percent of children in the U.S. were thought to have Attention Deficit Hyperactivity Disorder (ADHD) before the early 1990s, but in the following two decades since then, that figure has ballooned to 11 percent, according to the CDC in a report from the New York Times. The rapid increase likely has to do with sociological changes, including how kids use the internet and mobile devices for both educational and leisurely purposes.