 Studies have shown that preterm infants, full-term infants, and older infants have greater time periods of quiet sleep and also decreased time awake when they are positioned to sleep on their stomachs.In both human infants and rats, arousal thresholds have been shown to be at higher levels in the electroencephalography (EEG) during slow-wave sleep.In 1992 a SIDS risk reduction strategy based upon lowering arousal thresholds during SWS was implemented by the American Academy of Pediatrics (AAP) which began recommending that healthy infants be positioned to sleep on their back (supine position) or side (lateral position), instead of their stomach (prone position), when being placed down for sleep.