Prior Nighttime Sleep and Face Recognition in 6‐ and 12‐Month‐Old Infants

The role of prior sleep, particularly nighttime sleep, in memory encoding is poorly understood in infants. The present study, therefore, focused on possible associations between nighttime sleep and memory encoding in the first year of life. First, the sleeping behavior of 6-month-old (n = 32) and 12-month-old (n = 35) infants was assessed for one night using actigraphy and sleep diaries. The following day, infants participated in a visual recognition memory task in the laboratory, which included photographs of female adults showing happy, angry, and neutral facial expressions. Six-month-old infants did not recognize any of the faces, whereas 12-month-old infants recognized the emotional, but not neutral faces, as indicated by novelty preference scores. Correlation and hierarchical regression analyses revealed that sleep efficiency and light sleep predicted novelty preference scores for angry and neutral faces in 6-month-olds, whereas light sleep and co-sleeping predicted novelty preference scores for angry faces in 12-month-olds. These results suggest that specific sleep parameters have distinct and age-specific significance for subsequent memory encoding.