A baby's brain is constantly working and creating new knowledge even while they sleep, according to scientists from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and researchers from the University of Tubingen. Head of the study Angela Friederici said, "The waking infant brain quickly forgets newly learned names, but during sleep, words are more durably linked to objects and imprinted."
Sleep is much more than just relaxation for our brain. The flow of information from the sensory organs is largely cut off when we sleep, but many regions of the brain are especially active. Most brain researchers believe that the sleeping brain retrieves recent experiences, thereby consolidating new knowledge and integrating it into the existing memory by strengthening, re-linking or even dismantling neuronal connections. Thus, sleep is indispensable for memory.
During the study, 9 to 16 months' infants were taught the names of individual objects during a training session, irrespective of their age. The situation with categorization, however, was different and at the end of the training session, it was seen that they were unable to assign new objects to the names of similar objects which they had heard several times. During the subsequent testing session, the brain activity of infants who had a short nap after the training session was remarkably different from that of the group who had stayed awake.
The group who had stayed awake had forgotten the names of the individual objects, while the children in the sleep group remembered the object-word mappings. Radical differences in their abilities to categorize the objects were also noted.
The children's age had no effect on the learning outcome. But, a particular type of rhythmic activity of the sleeping brain called the sleep spindle had a significant impact on learning outcomes. Infants with high sleep spindle activity are particularly good at generalizing their experiences and developing new knowledge while sleeping. Researcher Manuela Friedrich explained, "The greater an infant's spindle activity, the better it can assign category names to new objects after sleep."