This evidence-based baby sleep chart can't tell you exactly how long your baby needs to sleep.
But researchers have collected information from parents about their babies' sleep habits.
Based on these surveys, we have a pretty good sense of what's typical -- the normal range of variation that parents report.
So what does normal sleep look like in babies?
The quick answer is summed up in this baby sleep chart.
* Nighttime sleep duration and range for middle 50% of the population derived from a study of Canadian and U.S. parents only (Sadeh et al 2008).
Other estimates derived from review of multiple, international studies (Galland et al 2012). Numbers rounded to nearest 0.5.
To create this chart, I have relied primarily on a meta-analysis by Barbara Galland and her colleagues (2012).
These researchers estimated average values for baby sleep statistics by combining data from studies conducted in Australia, Canada, China, Italy, Israel, Russia, Switzerland, the United Kingdom, and the United States.
Information in my chart about average total sleep duration, the range for 95% of the population, naps, night wakings, and the longest reported sleep bout reflects these values.
But Galland's team didn't provide estimates for every variable. For example, their analysis didn't include detailed data about the range for total sleep duration for half of the population. Nor did they report information about nighttime sleep duration.
So I used another source to fill this gap -- a survey of Canadian and U.S. parents (Sadeh et al 2008).
We shouldn't assume that information from this North American study will be representative of babies internationally (see below).
However, for every age group, the average total sleep duration for the North Americans was very close to the international averages. And the range for total sleep duration looked roughly consistent with graphical information provided by Galland's team (figure 3, p. 218, Galland et al 2012).
Averaging together international data is helpful for getting the big picture. But if we take a look at specific countries, we learn something more:
Studies report substantial variation from one society to the next.
For example, in a study conducted in Switzerland, the average total sleep duration for babies aged 6-12 months was about 14 hours -- an hour higher than the international average (Iglostein et al 2003; Galland et al 2012).
And researchers have found evidence for a broad cultural trend. Children living in Asian countries tend to sleep less than
do children living in Western, predominantly Caucasian countries (Galland et al
2012; Mindell et al 2010).
As you can see from the baby sleep chart, there is consideration variation.
What does this variation mean? Is there an optimal sleep duration for infants? Should you be worried if your baby sleeps less than average?
It's hard to answer these questions because researchers lack a clear understanding of the behavioral and health consequences of baby sleep patterns. We need more studies to sort this out.
As a result, the American Academy of Sleep Medicine has declined to offer concrete recommendations for sleep duration in babies under 4 months of age (Paruthi et al 2016).
For older babies (4-12 months), the Academy has advised that babies who get 12-16 hours every 24 hours are less likely to experience behavioral problems (Paruthi et al 2016).
But there is at least one reassuring observation for parents with babies who get less sleep than normal: For most of these babies, total sleep duration moves closer to average as they get older (Magee et al 2014).
And when researchers track these individuals over time, they have found no obvious long-term differences in emotional or social functioning. Infants who sleep less than average tend to be more irritable. But as long as sleep duration becomes more typical over time, kids seem to turn out pretty well (Magee et al 2014).
It's also helpful to keep in mind that the sleep times reported in this baby sleep chart don't reflect objective measures of how much babies sleep.
Instead, the reports are based on the (fallible) impressions of parents.
In some studies, parents are asked to keep careful sleep diaries. In other studies, parents merely fill out brief questionnaires about their children's past habits -- questionnaires which they answer from memory.
Either way, parents can be wrong, and research suggests that parents tend to overestimate how much their babies sleep.
This is understandable, because parents don't lie awake all night to confirm what their babies are doing. If the night seems quiet, parents may simply assume that their infants are sleeping. But are they really?
When researchers have measured baby sleep using objective methods -- like continuous, overnight video recordings -- they've found that babies sleep less (and awaken more frequently) than parents realize.
For example, one study found that babies 6-12 months woke up, on average, about 3 times during the night (Goodlin-Jones et al 2001). Yet many parents with babies this age report only one waking per night.
The Swiss study mentioned above (Iglowstein et al 2003) included information about total hours of daytime sleep, a statistic that wasn't provided in the international analysis by Galland and colleagues.
For this reason, I offer this last baby sleep chart based on the Swiss research. But remember that baby sleep patterns may vary by culture and region. We can't assume that the average number of daytime sleep hours is the same in other places.
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Content of "What's normal? An evidence-based baby sleep chart" last modified 5/2018
image of sleeping newborn by Guian Bolisay/flickr