Thus, sleep has effects on the quality and the quantity of adult memories.
Recently, research has shown that, unlike in adults, sleep seems especially valuable for declarative, rather than nondeclarative, memory consolidation in preschool- and school-aged children (7–11).
However, very little is known about the role of sleep in early memory processing.
Here we test 6- and 12-mo-old infants’ declarative memory for novel actions after a 4-h [Experiment (Exp.) 1] and 24-h delay (Exp. Infants in a nap condition took an extended nap (≥30 min) within 4 h after learning, whereas infants in a no-nap condition did not.
Does sleep already contribute to memory consolidation in the first year of life?
Here we test in two experiments whether sleeping after learning facilitates 6- and 12-mo-old infants’ declarative memory consolidation, using a well-established deferred imitation paradigm (18–21).
The potential benefits of infant sleep for memory processing are largely unexplored.
Here we show evidence that having an extended nap (≥30 min) within 4 h of learning helps 6- and 12-month-old infants to retain their memories for new behaviors across a 4- and 24-h delay.
In addition to facilitating memory consolidation and, thus, helping adults to retain memories over time (4), “sleeping on it” enhances, for example, the obtainment of new insights into previously encountered problems (5) and the flexible connection of existing stores of knowledge (6).
In Experiment (Exp.) 1, we assessed memory after a 4-h delay during which infants in a nap condition slept for at least 30 min uninterruptedly.
A 4-h delay was chosen because this interval has been successfully used in previous studies (15, 16) and because the longest awake period for 6-mo-old infants is typically just over 4 h (26).
Critically, however, it is not clear which form of memory underlies these effects (17).
Knowing which type of memory is measured when assessing effects of sleep on memory in a certain developmental phase is vital.