Sleep-states alter the influences exerted by suprapontine structures on respiratory and cardiac patterning. These influences consist of normal modulation exerted by descending cortical and limbic structures, and include hypothalamic temperature control. Rapid eye movement sleep dissociates hypothalamic activity from temperature control and nearly abolishes blood pressure rises and respiratory pattern changes induced by stimulation of suprapontine regions. Sleep-states also regulate the occurrence of aberrant cardiorespiratory influences from epileptiform activity manifested in suprapontine structures by altering the threshold for seizure incidence. Thus, sleep may pose particular states of vulnerability for the Sudden Infant Death Syndrome (SIDS), since both temperature influences on respiration and aberrant suprapontine epileptiform activity may be factors underlying the mechanism of failure in SIDS.