OBJECTIVE To longitudinally examine sleep patterns, habits, and parent-reported sleep problems during the first year of life. METHODS Seven hundred four parent/child pairs participated in a longitudinal cohort study. Structured interview recording general demographic data, feeding habits, intercurrent diseases, family history, sleep habits, and parental evaluation of the infant's sleep carried out at 1, 3, 6, 9, and 12 months. RESULTS Nocturnal, daytime, and total sleep duration showed a high inter-individual variability in the first year of life associated with changes in the first 6 months and stability from 6 to 12 months. Bedtime was at around 22:00 and remained stable at 6, 9, and 12 months of age. Approximately 20% of the infants had more than 2 awakenings and slept more often in the parent bed. Nearly 10% of the infants were considered as having a problematic sleep by parents and this significantly correlated with nocturnal awakenings and difficulties falling asleep. CONCLUSIONS Sleep patterns change during the first year of life but most sleep variables (i.e., sleep latency and duration) show little variation from 6 to 12 months. Our data provide a context for clinicians to discuss sleep issues with parents and suggest that prevention efforts should focus to the first 3-6 months, since sleep patterns show stability from that time point to 12 months.