Sleep and infant development in the first year

The trajectory of sleep in the first year of age is highly dynamic and correlates with developmental progress from the neonatal to the infantile period. During this critical period of brain growth, sleep facilitates neural maturation and memory consolidation. This review article examines the current evidence regarding the relationship between sleep and neurodevelopment in the first year of age. Over the first year, total sleep time decreases, nocturnal sleep consolidates with less nocturnal awakenings, and daytime sleep decreases. The dominant sleep state shifts from active sleep in neonates to non-rapid eye movement sleep at 12 months. Specific electroencephalogram (EEG) features include tracé alternant in neonates and sleep spindles and K complexes in infants. Characteristics of sleep spindles serve as biomarkers for neurodevelopmental outcomes. Adequate sleep duration is associated with enhanced white matter development. Healthy sleep parameters are linked to improved memory, language, executive function, sensorimotor skills, and overall cognitive development, whereas abnormal sleep during infancy is associated with cognitive, behavioral, and emotional disturbances. Developmental brain disorders and certain medical conditions are also associated with sleep disruption, indicating a bidirectional relationship. Sleep evolves rapidly in the first year of age, and adequate quantity and quality of sleep are critical for neurodevelopment. IMPACT: Sleep evolves significantly and rapidly during the first year, serving critical and active processes for neuromaturation. These sleep changes occur concurrently with major neurodevelopmental progress. Certain medical conditions, environmental exposures, and socioeconomic factors can disrupt sleep, potentially resulting in neurodevelopmental delay. Additionally, neurodevelopmental disorders are frequently associated with disruption in normal sleep architecture, suggesting a bidirectional relationship between sleep disruption and abnormal neurodevelopment. Future research should explore the neurodevelopmental consequences of medical and socioeconomic conditions that disrupt sleep. It is also essential to identify interventions to mitigate cognitive and behavioral disturbance arising from sleep disruption and to protect sleep health.