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