The Science of Infant Sleep Part III. Relationships that Influence Babies' Sleep

In this series, we've been sharing information about how and why infants' sleep patterns change as they grow. In this post, we'll focus on the how characteristics of babies, parents, and sleep environments interact to influence how infants sleep.

In other posts, we've talked about why a "one size fits all" sleep intervention is not likely to work for all babies. That's because there is no one reason why babies sleep the way they do. Their own bodies and abilities, how and when they are cared for, and where they sleep, all work together to help or hinder babies' sleep. Parents need to keep this bigger picture in mind.

Baby Characteristics

While parents can and do shape many of their babies' behaviors, babies come into the world as unique human beings with combinations of traits all their own. Your baby's sleep patterns will be affected by her age, health, physiology (like her ability to make and respond to hormones), exposure to medications or stimulants (like caffeine), her development, stomach capacity, day time activity level, feeding pattern, intake, temperament, and sensitivity to the environment. Each of these factors can influence her sleep patterns differently.

Family Characteristics

Parents and other caregivers are, of course, as unique as their babies. Some important characteristics that may influence infant sleep include parents' own physical and emotional health, cultural and family experiences, sensitivities to baby behaviors, and infant feeding practices. Most of these factors affect babies' sleep because they have powerful influences on parents' day and night time infant care behaviors.

Sleep Environment Characteristics

Babies' sleep patterns may also be influenced by their physical environment. Sounds, sights (like lights from a TV), movement, comfort, and temperature of the places where babies sleep all make a difference for sensitive babies. These factors affect babies differently depending on whether they are in a lighter (active) or deeper (quiet) state of sleep and babies' bodies influence how long they stay in each type of sleep.

Interactions and Babies' Sleep

All this means that babies' sleep patterns emerge when all of these factors come together, like puzzle pieces. We can't always predict what babies will do. For example, older babies with bigger stomachs may wake when they are sick, teething, or sleeping in a room that is too hot or cold even after they have slept for longer stretches for awhile. City-dwelling younger babies may stay asleep despite loud noises and lights because their bodies have adapted to what goes on around them. Parents' interactions can make a difference too. Parents checking on babies in active sleep might inadvertently wake their babies or babies might sleep longer at night for parents who make sure that their babies have lots of daytime activity. But parent interactions can only go so far if babies bodies are not ready to sleep longer or they are sleeping in an unfamiliar environment (like grandma's house).

Next time, we'll wrap up this series and talk about what all this means for tired parents, how sleep patterns change in older babies, and the research we found about putting babies down partially awake.


Next time: The Science of Infant Sleep Part IV: Older Babies, Falling Asleep versus Staying Asleep