Your baby's first words are a critical milestone in their development - and parents focus on encouraging them with'baby talk'. But now researchers have shown the importance of sleep when it comes to an infant learning to talk. In particular, sleep helps the important process of associating meanings to words - and not just perceive them as random noise. They found that babies as young as six to eight months old were capable of the association - which until now was thought to happen later on. And this occurred as a direct result of them being put down for a midday nap, the researchers say.