Infancy (0–2 years): This period is dominated by rapid brain growth and physical development. Nutrition is foundational – the “first 1000 days” (conception through age 2) are critical for neural development . Breastfeeding or formula provide essential nutrients (fatty acids, iron, iodine, choline, etc.); deficiencies in infancy (e.g. iron or iodine deficiency) can impair brain growth and later IQ . Early learning/stimulation comes through caregiver interactions: talking, singing, and play stimulate language and cognition, while formal education is minimal. Screen time should be avoided or minimal (AAP advises no screens under 2) because excessive TV or mobile use can delay language and hamper attention . Parenting style/emotional support is crucial: responsive, nurturing care fosters secure attachment and lays the emotional foundation for all learning . For example, when infants’ cries are promptly and gently met, their brains encode safety and allow exploration; chronic unmet needs or stress can undermine emotional and intellectual development . Sleep and activity are also vital: infants need many hours of sleep (up to ~14–17 hours) which support neural consolidation , and supervised “tummy time” builds early motor skills. In summary, nutrition plus emotional bonding are the most critical factors in infancy: optimal feeding and caregiver interaction together maximize brain and physical growth, whereas excessive screens and inadequate feeding pose immediate risks.
Early childhood (3–6 years): Growth is steadier but cognition and behavior accelerate. Nutrition remains important for continued brain and body growth – a varied diet of fruits, vegetables and proteins prevents anemia and supports memory and attention . Micronutrient gaps (e.g. iron, zinc, DHA) in preschoolers still predict delays in reasoning and attention . At this stage, early education and stimulation (preschool, storytime, play-based learning) strongly boost cognitive and social skills. Indeed, meta-analyses find preschool programs yield substantial gains in IQ, language and even social competence . Screen/media habits: Children often encounter tablets or TV in these years. Research shows moderate co-viewed, educational media may be neutral or slightly beneficial, but high screen use (beyond ~1–2 h/day) is linked to worse executive function and inattention , as well as poorer sleep. Parenting style/emotional support: Warm, authoritative parenting (rules plus warmth) fosters self-control and emotional regulation in this age. Conversely, harsh or unpredictable discipline is associated with behavior problems. Secure, loving interactions continue to buffer stress and encourage exploration. Physical activity and sleep: Preschoolers require ~10–13 hours of sleep for optimal learning; better sleep is consistently tied to improved mood and cognition . Regular active play (outdoor running, jumping) strengthens motor skills and even executive function – exercise programs in 7–12 year-olds show small but significant boosts in inhibitory control .
Middle childhood (7–12 years): School-age children deepen academic and social learning. Nutrition: A balanced diet still underpins health and learning. Overweight or nutrient-poor diets can impair concentration and mood. In low-resource settings, undernutrition during this period is linked to lower test scores and poor growth. In fact, even at 6–12 years, undernourished children given nutrition interventions show gains in cognitive tests . Education: Formal schooling becomes the dominant influence on intelligence and academic skills. Quality of teaching, learning resources and enrichment determine cognitive progress. Nutrition plays a supporting role (e.g. breakfast programs can modestly improve attention), but intensive mental stimulation through school is the main driver of cognitive gains. Screen time: Video games and internet use rise in middle childhood. Excessive gaming/social media is associated with increased sedentary behavior and obesity , and can distract from homework or family interaction. It also can impact social skills (e.g. cyberbullying or reduced face-to-face play). Parenting/emotional support: Steady, supportive parenting continues to shape behavior and social learning – consistent rules and emotional dialogue help children regulate emotions and peer interactions. Physical activity and sleep: Childhood is peak time for organized sports and active play. Regular exercise not only builds strength and immunity but also improves cognition – as noted, chronic physical activity yields better executive function . Adequate sleep (9–11 h) remains linked to sharper memory, mood stability and fewer behavioral issues .
Adolescence (13–18 years): Teenagers undergo another growth spurt and neural reorganization (prefrontal cortex maturation). Nutrition: Teens need increased calories and nutrients (iron for growth/spurt, calcium/vitamin D for bones). Poor diet (high sugars, fats) can worsen mood and weight. Evidence on diet–mental health in teens is emerging: cross-sectional studies link sugary diets with anxiety/depression, and teen nutrition programs suggest potential mental health benefits (though research is mixed) . Education: School quality and academic support remain crucial. Homework, advanced instruction and cognitive challenges shape intelligence and later achievement. Nutritional status can affect energy and concentration – e.g. studies show adolescents with improved nutrition (especially correcting deficiencies) show better cognitive outcomes – but schooling and motivation are often larger factors at this age. Screen/media: Screen use often peaks in adolescence. Excessive screen and social-media use is repeatedly linked to sleep disturbance and to higher rates of depression and anxiety . Poor sleep from late-night devices can directly impair cognitive performance. Limiting screen time or encouraging quality content can mitigate risks. Parenting/emotional support: Teens seek independence, but parental guidance and emotional support still buffer stress and encourage healthy decisions. Authoritative parenting remains associated with better emotional stability and social skills, whereas neglect or harshness can exacerbate risk-taking or anxiety. Physical activity and sleep: Physical activity often declines in adolescence, but maintaining regular exercise is vital – it helps regulate mood (endorphins reduce anxiety/depression) and sustains cognitive function . National recommendations (≥60 min/day) aim to embed lifelong habits. Sleep is critical yet under-met: most teens need ~8–10 h, and sleep deprivation is linked to worsened grades, memory deficits, and mood disorders .
Comparing Factors Across Domains: Recent research highlights that nutrition is essential for brain and body foundation—especially in infancy and early childhood . For cognitive development and intelligence, early nutrition (breastfeeding and micronutrients) plays a major role in the first 2–3 years , but as children age, education and cognitive stimulation often dominate. A comprehensive review notes that targeted school feeding programs can enhance cognitive function and academic performance, especially in underprivileged kids , yet overall it finds that learning environment (education + enrichment) and parenting are equally critical factors. In contrast, emotional regulation and behavior are largely driven by parenting style and support . Good nutrition supports stable mood (e.g. steady blood sugar, essential fatty acids for neurotransmitters), but its influence is moderate compared to the secure attachments and self-regulation modeled by caregivers. Notably, poor nutrition can worsen behavior and social functioning , but interventions on diet alone produce only modest emotional gains . Sleep quality emerges as another strong factor here: consistent sleep boosts emotional well-being and reduces behavioral problems .
For physical health and immunity, nutrition and physical activity are paramount. Proper feeding ensures normal growth, strong bones, and a robust immune system (e.g. breastmilk delivers antibodies in infancy, and ongoing healthy diet reduces infection risk). Multiple studies show even healthy children see immune boosts from regular exercise , and physical fitness combats obesity. Screen sedentism, by contrast, consistently correlates with obesity and poor metabolic health . Sleep also bolsters immunity (chronic sleep loss elevates inflammation and infection risk). In summary, nutrition, exercise and sleep work together to optimize physical outcomes; of these, nutrition (calories/nutrients) is fundamentally necessary, but activity and rest are almost equally important for resilience.
Regarding academic performance and social skills, education and the learning environment are key drivers. Nutrition contributes by enabling concentration and reducing absenteeism (malnourished children miss more school). One systematic review concluded that school-based nutrition programs tend to improve not only health but also cognition and grades , especially in disadvantaged settings. However, the overall weight of nutrition on achievement is modest: meta-analyses suggest that factors like parental involvement, teacher quality, and students’ emotional well-being often have larger effects on academic success. Screen time can indirectly hurt academic and social development by displacing study or face-to-face interactions and by fragmenting attention . Parenting and peer influences heavily shape social skills and learning attitudes. In practice, nutrition is a necessary foundation for learning (it supplies energy/brain nutrients), but early education and nurturing home/school environments exert the most powerful effects on academic and social outcomes.
Summary of Key Influences by Age: In infancy, feeding and nurturing care top the list: adequate nutrition and secure attachment jointly build the brain’s architecture . By early childhood, balanced diet plus rich learning opportunities (preschool, language-rich play) are critical; screens should be limited, and consistent routines (sleep, activity) support all domains. In middle childhood, formal education and healthy lifestyles (good diet, exercise, sleep) drive development – nutrition prevents deficits, but cognitive gains come mostly from schooling and active engagement, while physical health benefits from movement and rest. In adolescence, psychosocial support and healthy habits become crucial: nutrition sustains the body’s final growth and brain maturation, but mental health (peer support, family stability), sleep hygiene, and physical activity strongly influence mood, cognition, and social skills.
Overall, nutrition plays a vital foundational role – especially early on – but its relative importance shifts as children grow. In infancy and early childhood, nutrition (along with caregiver bonding) may be the single most critical factor for brain/physical growth . In later childhood and adolescence, education, emotional support, and lifestyle factors (sleep, exercise, media habits) often have greater additional impact on outcomes, even though good nutrition remains necessary. Policy and expert guidelines therefore emphasize a holistic approach: combine healthy feeding practices (breastfeeding, varied diet, micronutrient sufficiency) with quality early education, limits on screen time, warm parenting, and regular sleep/activity. This multifaceted strategy best supports cognitive performance, emotional health, physical growth, and long-term success at every stage .
Sources: Recent reviews and studies on child development, nutrition, sleep, screen time, and parenting are cited above (e.g. ). These document the roles of diet and other factors at each developmental stage.