Between 1974 and 1984 we have studied 204 control infants (C) comparing them with 650 SIDS siblings (SS) and 146 near-miss for SIDS (NM). These 1,000 full-term infants were recorded by day polysomnography (DPSG; n = 417), night polysomnography (NPSG; n = 257) and cardiopneumography (CPG; n = 2,600). Records were visually analyzed. In DPSG and NPSG, total amount of central, mixed and obstructive apnea as well as the percentage of periodic breathing was studied in each sleep state (active sleep, AS; quiet sleep, QS; indeterminate sleep, IS, and total sleep, TS) and over the total recording time (TRT). In CPG, only the total amount of central apnea and percentage of periodic breathing over TRT were studied. Infants were grouped according to postnatal age: less than 5, greater than or equal to 5 to less than or equal to 13, and greater than 13 to less than or equal to 26 weeks. In each age group results were compared as follows: C vs. SS, C vs. NM, and SS vs. NM for each parameter studied. Before 5 weeks and after 13 weeks there was no significant difference between C and SS, C and NM, and SS and NM in DPSG and NPSG for all categories of central, mixed and obstructive apnea as well as the percentage of periodic breathing in different sleep states and over TRT. Similar results were obtained in CPG for all categories of central apnea and percentage of periodic breathing over TRT.(ABSTRACT TRUNCATED AT 250 WORDS)