Sleep and neurofunctions throughout child development: lasting effects of early iron deficiency.

Iron-deficiency anemia (IDA) continues to be the most common single nutrient deficiency in the world. Infants are at particular risk due to rapid growth and limited dietary sources of iron. An estimated 20% to 25% of the world's infants have IDA, with at least as many having iron deficiency without anemia. High prevalence is found primarily in developing countries, but also among poor, minority, and immigrant groups in developed ones. Infants with IDA test lower in mental and motor development assessments and show affective differences. After iron therapy, follow-up studies point to long-lasting differences in several domains. Neurofunctional studies showed slower neural transmission in the auditory system despite 1 year of iron therapy in IDA infants; they still had slower transmission in both the auditory and visual systems at preschool age. Different motor activity patterning in all sleep-waking states and several differences in sleep states organization were reported. Persistent sleep and neurofunctional effects could contribute to reduced potential for optimal behavioral and cognitive outcomes in children with a history of IDA.

Sleep alterations and iron deficiency anemia in infancy.

Iron deficiency anemia (IDA) continues to be the most common single nutrient deficiency in the world. An estimated 20-25% of the world's infants have IDA, with at least as many having iron deficiency without anemia. Infants are at particular risk due to rapid growth and limited dietary sources of iron. We found that infants with IDA showed different motor activity patterning in all sleep-waking states and several differences in sleep states organization. Sleep alterations were still apparent years after correction of anemia with iron treatment in the absence of subsequent IDA. We suggest that altered sleep patterns may represent an underlying mechanism that interferes with optimal brain functioning during sleep and wakefulness in former IDA children.

Iron deficiency anemia in infancy is associated with altered temporal organization of sleep states in childhood.

The highest prevalence of iron deficiency anemia (IDA) in infancy coincides with a time of rapid changes in sleep organization. Since IDA in infancy is associated with long-lasting neurofunctional effects despite iron treatment, the normal development of sleep patterns might be affected. Night polysomnographic recordings were performed in 55 healthy 4-y-old children (former IDA = 27, nonanemic controls = 28). Both groups were followed from infancy and were similar in background characteristics. The duration of each waking episode was measured, as was the duration of each episode of nonrapid eye movement (NREM) sleep stages 1 (NREM1), 2 (NREM2), and 3-4 (SWS), and rapid eye movement (REM) sleep. The data were analyzed according to the successive thirds of the total sleep time (TST). Relative to controls, former IDA children showed: a) longer duration of REM sleep episodes in the first third and shorter in the last third; b) more REM sleep episodes in the first third and fewer in the second third; and c) shorter latency to the first REM sleep episode and shorter NREM stage 2 and SWS episodes within the first sleep cycle. The results show that early IDA is associated with long-lasting alterations in the temporal organization of sleep patterns.