Over the first months of life, the relative amount of time spent in the different _______ of sleep changes. The stage of sleep characterized by flickering eyes behind closed lids and _______ is called ______ ____. During the stage of sleep, brain waves are fairly _____ over the first months, as does the dozing stage called ____ ___. Slow wave sleep, also called ____ ____, increases markedly at about ____ months of age.