The aim of this study was to investigate the influence of the use of headphones in salivary cortisol levels in newborns (NB) during periods of nap aimed at noise reduction, brightness and handling NB, measure the concentrations of salivary cortisol before (baseline) and after the use of hearing protection (response) in the NICU nap periods and compare the influence of the use and non-use of hearing protection in salivary cortisol levels and sleep patterns of infants during nap periods of the NICU. Being the chance prosposta the use of headphones during periods of environmental control has an influence on the level of salivary cortisol and sleep in preterm infants.