What Too Much Screen Time Does to Young Kids (And What We Can Do About It)

Here’s a draft blog post on the effects of screen time on young children. Feel free to edit, reshape or shorten as you like.

Introduction
We’re in a world where screens — TVs, tablets, phones — are everywhere. For kids under five, whose brains are growing fast, how they engage with screens matters. Plenty of peer-reviewed research now shows that more screen time isn’t just “quiet time for mom/dad” — it can have measurable effects on development, behaviour, sleep and more. In this post I’ll summarise what the research says and pull out practical take-aways for parents, caregivers and educators.

1. What the research says: key findings
Here are some of the most important results, drawn from recent peer-reviewed studies.

a. Developmental delays & cognitive/language issues

• A large cohort study in Canada found that children average age 5.2 years who had more than one hour per day of screen time were more likely to be “vulnerable” in developmental domains (language/cognitive, communication, social competence) versus children with up to one hour/day. (BioMed Central)

• Another cohort of children at 24 and 36 months found that higher screen time at those ages was significantly associated with poorer performance on developmental screening tests at 36 and 60 months. (PMC)

• A review on children under 5 summarised both risks and possible benefits of screen media but emphasised that “the digital landscape is evolving more quickly than research” for that age group. (PMC)

• Recent systematic review (2024) on children aged 0-36 months found that for most developmental outcomes (sleep, cognition, language, motor skills, socio-emotional), undesirable or non-significant associations dominate; desirable associations are rare. (Frontiers)

b. Sleep, physical health & behaviour

• Higher screen time is clearly linked with poor sleep quality/shorter sleep, and in turn those sleep problems are linked with behavioural health problems. (PMC)

• Screen time is associated with poorer physical activity levels, higher sedentary time and in younger children less movement — which then can impact overall development. (MDPI)

• A longitudinal study from China found screen time at 6 months and 2.5 years was a risk factor for emotional symptoms and hyperactivity at age 4. (BioMed Central)

c. Social, emotional, and interactional effects

• Some evidence shows that screen time can interfere with the type of interaction young children need for socio-emotional development — e.g., watching screens instead of interactive play or adult-child interaction may reduce opportunities for rich learning. (NewYork-Presbyterian)

• The review for children under 5 emphasises that beyond just “how long” the screen is used, the type of content, context (co-viewing with parent) and how screen time fits into the child’s overall schedule matter. (PMC)

2. What we don’t yet fully know / caveats

• Correlation vs causation: While many studies find associations between higher screen time and poorer outcomes, it’s not always clear that screen time causes the issue rather than being a marker for other risks (e.g., lower socio‐economic status, less parental interaction, etc.). The Canadian 5-year-old study controlled for some factors, but these kinds of issues remain. (BioMed Central)

• Quality, content, context matter: A screen showing an educational app with an engaged adult differs markedly from passive TV watching alone. Some of the literature acknowledges benefits of high-quality content + adult mediation. (PMC)

• Age variation: The evidence is stronger for children under age 5 and especially under age 3, but patterns may differ for older children. (Frontiers)

• Dose / threshold is still vague: Exactly how many hours is “too many” remains debated, especially given differences in content, context, child characteristics. The one-hour / two-hour thresholds are used in many studies, but not universally.

3. Practical take-aways (for parents/caregivers/educators)
Based on the research, here are actionable guidelines:

• For very young children (under ~2-3 years): Limit screen time. If screens are used, favour high-quality, interactive media and co-viewing with a caregiver rather than passive solo screen time.

• For preschoolers (ages ~3-5): Aim to keep screen time modest — some studies suggest more than one hour/day is where risks increase.

• Ensure screen time doesn’t replace active play, interaction with caregivers/peers, and sleep/physical activity. Those seem to be the mechanisms by which risk comes in.

• Be mindful of timing: Avoid screens right before bedtime or in place of sleep/active play.

• Encourage alternative activities: unstructured play, reading/being read to, outdoor time, imaginative play.

• Model good behaviour: Caregivers’ own screen habits set norms for children.

• Focus on content: When using media, pick age-appropriate, high-quality content; co-view and scaffold learning rather than letting the child passively consume.

• Create "screen free" zones/times: e.g., at meals, in bedrooms, certain parts of the day.

• Be aware of the bigger picture: Screen time is one piece of the puzzle of childhood development; family context, socio-economic factors, sleep, nutrition and play all play roles.

4. Why this matters
Young childhood is a period of rapid brain growth, language acquisition, social skill development -- the foundation for everything that follows. When screen time starts to displace opportunities for active learning, interaction, and physical exploration, we risk undercutting those foundations. As one review puts it: “Excessive screen time is associated with negative outcomes such as reduced physical activity, poorer sleep, attention difficulties, and challenges in emotional and social functioning.” (MDPI)
Given how pervasive screens are today, especially in households with multiple devices, this isn’t a fringe issue. It’s central to how we guide children’s healthy development in a digital age.

5. Conclusion
Screens are inescapable in modern life, and they offer real benefits (learning apps, linking with distant family, etc). But when they become a dominant mode of activity for young children — especially under age 5 — the research signals caution. Limiting time, choosing high-quality content, ensuring screen use doesn’t displace sleep, play, interaction, and physical activity: these are the essentials. The investment we make in how children engage with screens today pays off in how they develop tomorrow.

References (select peer-reviewed papers):

• “Effects of Excessive Screen Time on Child Development” – PMC. (PMC)

• “Screen time and young children: Promoting health and development” – PMC. (PMC)

• “Screen time and developmental health: results from an early childhood study” – BMC Public Health. (BioMed Central)

• “Association between screen time and children’s performance on a developmental screening test” – PMC. (PMC)

• “Impact of Screen Time on Children’s Development” – MDPI review. (MDPI)

If you like, I can pull together 10+ references with full citations (authors, year, journal, DOI) and also create a “what parents can do” infographic. Would you like that?