How baby sleep requirements are estimated

Everybody knows that babies need more sleep than older children do. But how much?

When I began researching baby sleep requirements, I assumed that those authoritative charts we see published everywhere—the ones telling us that the average newborn needs 16 hours of sleep, for example—were based on scientifically-established, biological needs.

I figured that somebody must have identified a link between, say, a certain minimum number of sleep hours and optimal rates of childhood growth. Or between sleep hours and rates of infection.

I was wrong.

It turns out that scientists know relatively little about baby sleep requirements. The sleep charts that you see in parenting books and websites are based on how much time parents—typically, American or European parents—say their babies spend sleeping.

For instance, studies of Western babies reveal that the average newborn sleeps about 16-17 hours a day (So et al 2007).

Do such average sleep times predict your baby's sleep requirements?

Maybe. It seems plausible that most infants are pretty good self-regulators of their own sleep needs. Give your baby enough opportunities, and he may naturally meet his own baby sleep requirements. If that's true—and if most parents give their babies the necessary opportunities—then studies of real-world sleep behavior may tell us a lot about baby sleep requirements.

But it's a bit more complicated than that.

For one thing, different individuals have different needs. This may be especially true for baby sleep requirements. As the data below show, babies vary tremendously in the number of hours that they sleep.

Another important point is that sleep habits vary from culture to culture. Children in living in different nations get different amounts of sleep, and average sleep times have changed from generation to generation.

Based on a recent telephone survey conducted by the National Sleep Foundation, American kids—including babies—seem to be sleeping less than they used to (National Sleep Foundation 2004).

A similar trend towards less sleep has been documented in Switzerland, (Iglowstein et al 2003), Saudi Arabia (Bahamman et al 2006), Hong Kong (Ng 2005), Australia (Smedje 2007), Israel, and Finland (Tynjala et al 1993).

Are contemporary kids in these countries getting the right amount of sleep? Some researchers suspect not. But until more research has been done, nobody knows for sure.

So sleep charts are not necessarily the Last Word on baby sleep requirements. To estimate your baby's own, individualized needs, you need to supplement information from sleep charts with your own observations of your baby's behavior.

Below I provide data from one of the best, most recent studies of average sleep times (Iglowstein et al 2003). As you check the numbers out, be sure to notice how widely sleep times vary for each age group.