Plenty of parenting websites will tell you the "right" time to put your children to bed. Many of these resources even include age-based charts broken into 15-minute sleeping and waking intervals so you'll know that if your five year old goes to bed at 6:45 she should be up at 6:00.
Surprisingly, these sleep guidelines are based on remarkably little evidence.
Before you waste time charting your child's sleep, or struggle to get your kids into bed while the sun's still up, read up on what's known about sleep, what's unknown, and what's negotiable.
Sleep is Poorly Understood
We all know we're supposed to be getting 8 hours of sleep a night. We know that our kids are supposed to be getting more than that. We also know that our families generally fall short of those guidelines, whether it's demanding work schedules, sleep-resistant toddlers, or just needing to enjoy our quiet houses in the late-night hours.
But how do we know how much sleep we need? Emmanuel Mignot, director of the Center for Sleep Sciences and Medicine at Stanford, calls sleep "one of the last remaining mysteries in biology." We know we need to sleep, but we don't really know why we need to sleep for a third of our lives, or why sleep-deprivation is so profoundly damaging.
Part of why sleep is poorly understood is that it is really hard to study. Sleep is governed by the brain, and brains are hard to study. Sleep studies are time consuming and expensive. They often require getting subjects to sleep in a lab, connected to various wires and measurement tools, for a prolonged period of time.
As a result, sleep studies tend to be quite small. And even then, the results are not necessarily applicable to the population at large. Children with sleep issues may undergo sleep testing to study their sleep patterns. These sleep studies are helpful in diagnosing and treating a range of medical concerns, from sleep apnea to sleepwalking. But they cannot be generalized to how all children should sleep.
Sleep Recommendations are Broad
If the available sleep studies don't explain how much we should sleep, where do these recommendations come from? How do professional sleep organizations know what amount of sleep is ideal for children of each age group?
In a review of 100 years' of sleep recommendations, Lisa Anne Matricianni and colleagues found that only 1 of 35 formal recommendations provided specific scientific rationale behind its conclusions. The reviewers concluded that, "after more than 100 years, sleep recommendations are still being issued in the acknowledged absence of meaningful evidence." In short, the organizations making recommendations about children's sleep are not necessarily their guidelines on very strong evidence about children's sleep habits. The evidence tends to be largely anecdotal and practice-based, and while these observations have value, they are often the starting point, not the end point, of scientific research.
The lack of good sleep evidence makes sense. No study is going to definitively prove how much sleep anyone needs, because such a study would need to follow a subject over the course of a lifetime. It would require decades-long data collection on daily sleep, diet, and exercise, and even then there would be so many confounding variables that it would be difficult to draw definitive conclusions about how much sleep is necessary.
Although they were not able to pinpoint strong evidence undergirding each set of recommendations, Matricianni and colleagues found remarkable similarities between the rationales for the amount of sleep recommended in each set of guidelines. In nearly every case, there is expressed concern for children not getting "enough" sleep. The reviewers noted that, whether it was 1897 or 2007, people believed children's sleep to be adversely affected by modern life, from schoolbooks then to the internet now.
Perhaps the most comprehensive sleep guidelines to date are those put out by the American Academy of Sleep Medicine (AASM) in 2016. Drawing from hundreds of sleep studies, the AASM recommends the following daily sleep amounts for children:
12-16 hours for infants aged 4-12 months
11-14 hours for 1-2 year-olds
10-13 hours for 3-5 year-olds
9-12 hours for 6-12 year-olds
8-10 hours for 13-18 year-olds
These recommendations, which were endorsed by the American Academy of Pediatrics, are for total sleep time, including naps, during each 24-hour period.
The first thing to notice about these guidelines is how broad they are. There are wide gaps between the low and high sleep amounts for each group. There are also no optimal bedtimes included within the guidelines, or even the requirement that the sleep be continuous. The looseness of the guidelines suggests that either individual humans' sleep needs are so different as to defy categorization, or there is just not enough strong data to draw a definitive conclusion about sleep needs.
The American Early Bedtime
The above AASM recommendations do not recommend a specific bed time or wake time, but instead an overall amount of sleep by age group. But when translated into articles about parenting, those recommendations turn into strict requirements for children's ideal bedtimes.
That's not necessarily because earlier is better, but because American parenting--and American daily life in general--requires early bedtimes of us all.
First, our kids have to go to bed early because they have to get up early, a point Slate parenting columnist Melinda Wenner Moyer makes in her defense of the "absurdly early bedtime."
When we say that putting kids to bed early is better, we gloss over a really important distinction. It's not the early bedtime that matters so much as the amount of sleep children get. Children who go to bed at 7:00 can get 11 hours of sleep. Children who go to bed at 9:00 can get 11 hours of sleep. The difference is that, when parents have to be at work early, kids have to be awake early.
Second, our kids have to go to bed early because we need "alone" time.
Stories about early bedtimes often include the "me" time that parents want away from their children. There's no evidence that late bedtimes need to disrupt this sacred time for parents. That need for "me" time stems from more than just sleep schedules. It comes from our own cultural expectation to be 100% present with our children.
The combination of early morning wake times and the hyper-involved parenting expectations of many Americans is a losing combination that means somebody--maybe everybody--isn't going to get enough sleep.
Sleep is Cultural
The sleep guidelines offered by the AASM suggest that there are many different routes to the "right" amount of sleep. And internationally, that seems to be true. How kids get their sleep differs dramatically from one country to the next.
Even as we try to find the "right" bedtime, we can probably all recognize that people sleep differently and happily in different countries. (Think siestas!) Joanna Goddard's eye-opening Motherhood Around the World series helps showcase the difference in a wide range of parenting styles, including attitudes toward sleep, from Italian playdates that extend past many American kids' bedtimes, midnight snuggles during Icelandic summers, shared bedtimes for Indian parents and kids alike.
As examples from different countries show, there isn't necessarily a "right" way to get a full day's sleep. Armed with that knowledge, parents should feel more comfortable negotiating sleep times that work best for their kids and themselves, whether that's two-hour midday naps or getting the kids in bed before sunset.
This article originally appeared on Parent.co, which has been sleeping since 2018.