Sleep, Baby, Sleep… And Stay Asleep

Baby sleep patterns appear to be split into two categories of children

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Some debates never seem to have hope for resolution. One of those may be the discussion of whether parents should let babies cry themselves to sleep or not.

A recent study looked into this question a bit more by seeking out possible influences on baby's sleeping and waking patterns.

The study found that babies could be divided into two groups: Sleepers and Transitional Sleepers. Transitional Sleepers wake up much more often until 18 months old.

Transitional sleepers are also more likely to be breastfed and to have difficult temperaments, such as irritability or distractibility.

"Ask your pediatrician for baby sleep tips."

The study, led by Marsha Weinraub, PhD, a psychology professor at Temple University in Philadelphia, aimed to understand patterns of babies' sleep and what factors might affect those patterns.

The researchers included 1,364 families in the study who were socio-economically, racially and educationally diverse. None of the babies involved had been hospitalized for more than seven days.

The children were assessed at 6 months, 15 months, 2 years and 3 years old with home visits and questionnaires filled out by the mothers.

The mothers and their children also visited the research lab for child assessments and observation of the two playing when the child was 15 months, 2 years and 3 years old.

By 6 months old, most of the babies slept through the night except on one or two nights a week. Some children, however, followed a different developmental pattern.

Dr. Weinraub labeled these two groups as Sleepers – which was 66 percent of the children – and Transitional Sleepers, which included 34 percent of the babies.

The Sleepers only woke up their mothers an average of one night a week from age 6 months old to 3 years old. But the Transitional Sleepers woke up their mothers every night of the week at 6 months old. Not until 18 months old did the Transitional Sleepers awaken only one night a week as the Sleepers did.

By 15 months old, Transitional Sleepers only woke up their moms twice a week, which dropped to 1 night a week by the time the kids were 2 years old.

Dr. Weinraub and her colleagues also identified some significant differences between Sleepers and Transitional Sleepers.

Transitional Sleepers were more likely to be boys and were more likely to be breastfed at 6 months old and 15 months old.

The mothers of Transitional Sleepers were also more likely to be depressed when the babies were 6 months old and were more likely to describe their child's temperament as difficult at 6 months old.

The partners of Transitional Sleepers' moms were also more likely to have health issues, and Transitional Sleepers were more likely to come from large families and to spend less time in daycare at 9 months old.

However, Weinraub did not find any connection between the infants' sleeping patterns and the level of attachment between the mother and her child. The mother-child bond and the child's level of separation anxiety appeared unrelated to whether the child was a Sleeper or Transitional Sleeper.

Across both groups, Weinraub found that the children were more likely to wake their parents up if they had a difficult temperament, they were breastfed, they were sick or their mother was depressed.

Strangely, even though the level of mothers' sensitivity was not linked to whether the babies were Sleepers or Transitional Sleepers, in the overall analysis, the mothers' sensitivity was actually associated with how often the children woke their parents during the night.

"Infants whose mothers display sensitivity during play and structured interactions are more likely to continue to awaken more frequently than infants whose mothers are less responsive," the researchers wrote. "One explanation may be that generally sensitive mothers during the day are also more inclined to intervene when the infant shows signs of struggling with sleep."

In a release about the study, Dr. Weinraub pointed out that it may help the frequency of night wakings if parents allow babies to learn to fall back asleep on their own.

"When mothers tune in to these night time awakenings and/or if a baby is in the habit of falling asleep during breastfeeding, then he or she may not be learning to how to self-soothe, something that is critical for regular sleep," Dr. Weinraub said.

Birth order, family economic status, birth weight and the number of parents in the household were not related to how frequently the children woke their parents.

The research therefore revealed that even a "normal" child might not initially have "normal" sleeping patterns until a year-and-a-half old.

"These findings suggest that parents and primary healthcare providers should be aware that some infants who are generally healthy and typically developing might nevertheless have mothers who report sleep awakenings that extend into their infant’s second year of life," the researchers wrote.

"However, for nearly all healthy infants, sleep awakenings tend to abate by the middle of the second year," they wrote.

The researchers recommended that children who continue to wake up frequently past 18 months old be seen by a healthcare provider.

William Kohler, MD, the director of Pediatric Sleep Services at Florida Hospital Tampa and a dailyRx expert, noted that it can be difficult to tell what might be causing what with some of these findings.

"The children that do not sleep as well are more irritable – is that because of genetic factors or is the irritability from the poor quality of sleep?" Dr. Kohler said. Likewise, he noted that poor sleep can lead to depressive symptoms, and mothers of babies who don't sleep well will sleep poorly themselves.

"Is disrupted sleep the primary cause of the depression in the mothers, or is the depression a genetic problem which is contributing to a genetic issue in the children?" Dr. Kohler said. "It could be both."

Dr. Kohler's general advice to parents is to find out why their child is unable to go back to sleep after waking up.

"All children and adults wake up during the night and most of us turn over and go back to sleep and never remember waking up," he said. "There are children that wake up and can't get back to sleep. Why? Why aren't they self-soothing?"

In some situations, the child may have difficulty if the conditions that put them to sleep are not there when they wake up. "Once they wake up during the night, they're going to expect those conditions to be there," he said.

The study was published January 2 in the journal Developmental Psychology. The research was funded by the National Institute of Child Health and Human Development. No information was provided regarding disclosures.

Reviewed by: 
Review Date: 
January 11, 2013
Last Updated:
January 15, 2013