The effects of iron and/or zinc supplementation on maternal reports of sleep in infants from Nepal and Zanzibar

BACKGROUND: There is some evidence that sleep patterns may be affected by iron deficiency anemia but the role of iron in sleep has not been tested in a randomized iron supplementation trial. OBJECTIVE: We investigated the effect of iron supplementation on maternal reports of sleep in infants in 2 randomized, placebo-controlled trials from Pemba Island, Zanzibar, and Nepal. DESIGN: In both studies, which had parallel designs and were carried out in years 2002 to 2003, infants received iron-folic acid with or without zinc daily for 12 months, and assessments of development were made every 3 months for the duration of the study. Eight hundred seventy-seven Pemban (12.5 ± 4.0 months old) and 567 Nepali (10.8 ± 4.0 months) infants participated. Maternal reports of sleep patterns (napping frequency and duration, nighttime sleep duration, frequency of night waking) were collected. RESULTS: Mean Hb concentration was 9.2 ± 1.1 for Pemban and 10.1 ± 1.2 g/dL for Nepali infants. Approximately, one-third of the children were stunted. Supplemental iron was consistently associated with longer night and total sleep duration. The effects of zinc supplementation also included longer sleep duration. CONCLUSIONS: Micronutrient supplementation in infants at high risk for iron deficiency and iron deficiency anemia was related to increased night sleep duration and less night waking.