More than half of infants sleep through the night by age 5 months

By the age of 5 months, more than 50% of infants are following their parents’ sleep times and sleep through the night. The finding offers reassurance to concerned parents.

In study results published online in Pediatrics, researchers investigated the sleep patterns of 75 infants over the first year of life. Self-regulated nocturnal sleep was measured according to 3 criteria: 1) sleeping uninterrupted from midnight to 5 AM; 2) sleeping uninterrupted for a minimum of 8 hours between sleep onset and time awake in the morning; and 3) sleeping uninterrupted from 10 PM to 6 AM, congruent with family sleep.

The data were obtained from sleep diaries kept by the parents.

The start time for the longest self-regulated sleep period decreased from 10:30 PM at 1 month to 8:30 PM at 12 months. The largest increase in the length of self-regulated sleep occurred across the first 4 months.

Most infants satisfied criteria 1 and 2 by 2 months; for criterion 3, it was 3 months. The age at which at least 50% of the infants met each criterion was 3 months for criterion 1 (58%), 4 months for criterion 2 (58%), and 5 months for criterion 3 (53%).

By 12 months, 73% (criterion 3) to 87% (criterion 1) of the infants were sleeping through the night.

At age 3 months, there was evidence of concordance between the initial sleep onset time (9:46 PM), the longest self-regulated sleep period (8.2 hours), and typical family sleep schedules. The rate of sleep time plateaued between 4 and 9 months and lengthened again between 10 and 12 months.

Researchers believe that criterion 3 should be adopted to define “sleeping through the night” for infants. These findings about infant sleep development should provide a context to discuss sleep issues with parents, and indicate that sleep intervention can begin as early as 1 month “to be synchronous with the onset of sleeping through the night.”

Henderson JM, France KG, Owens JL, Blampied NM. Sleeping through the night: the consolidation of self-regulated sleep across the first year of life. Pediatrics. 2010;126(5):e1081-e1087.