Effect of infant sleeping position on sleep spindles

SUMMARY Sleep spindles play an active role in inducing and maintaining sleep and may affect arousal by blocking the transmission of external stimuli through the thalamus to the cortex. Previously we have demonstrated that sleeping in the prone position impairs arousal in infants at 2–3 months of age, but not at 5–6 months. We aimed to examine if sleeping position and postnatal age affected duration and/or density of sleep spindles. Twenty‐one healthy term infants were studied using daytime polysomnography at 2–3 months and 16 were again studied at 5–6 months. Infants slept both prone and supine at each study. The mean duration of non‐rapid eye movement (NREM) sleep was not different between the two studies in either position. At 2–3 months both spindle density (P