In clinical practice, I focus on applying practical assessment and intervention approaches. I will share my experiences on those in the future. For now, I am looking at what sleep looks like across cultures and countries.

In a previous post, I re-graphed data from the National Sleep Foundation’s 2026 survey of North American families alongside sleep guidelines from the National Sleep Foundation and the American Academy of Sleep Medicine. One implication for practice is that more awareness of the recommended total sleep durations is warranted, which could inform the timing of children’s bedtime. You can toggle on and off the different studies in the visual here.

As I have continued to look at research on sleep timing and duration of children, I noticed parent-reported sleep durations published by research teams from different countries. I was interested in studies that provide fine-grained, parent-reported sleep duration data in 1-year or 1.5-year intervals rather than aggregating across wide age bands (e.g., 3 to 5 year olds, 6 to 13 year olds). Below is a visual I created comparing data from four studies of families in the USA, Switzerland, Germany, and China.

You can toggle off and on the mean data from each country as well as the variability bands in the interactive graphical depiction here.

Above are data from Iglowstein and colleagues (2003; Switzerland) and Schlarb and colleagues (2015; Germany). The lines represent means; the bands represent the 25th to 75th percentile (50% of children). Swiss children slept 30 to 50 min longer than German children from about age 1 to age 6. The Iglowstein et al. cohorts were born between 1974 and 1993, which is 10 to 30 years before the other three studies collected their data. It is plausible that the sleep durations of Swiss children have decreased since the study was conducted, which would be consistent with a trend of later bedtimes and relatively unchanged wake times observed across the Swiss cohorts in the Iglowstein study.

Above are additional data from a Massachusetts (USA) cohort and Chinese families as obtained by Cespedes and colleagues (2014) and Li and colleagues (2013), respectively. On average, North American children slept less than German and Swiss children. Children in China slept the least for older age ranges.

The graph above shows pairwise differences between countries at each age. For example, German children slept more than American children across all overlapping ages, as indicated by the blue data points in the bottom left panel.

These data are descriptive, and there are differences in when and how these data were obtained. How much children sleep varies considerably depending on where and when children are raised. Cultural practices around bedtime (e.g., finishing academic work, later mealtimes, screen use near bedtime) and wake times likely contribute to these differences. This will be explored more in the future.

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The Study - National Sleep Foundation. (2026). Sleep in America Poll: A focus on America’s youngest sleepers

The National Sleep Foundation has conducted the Sleep in America Poll since 1991, with each edition focusing on a different theme (e.g., teens, technology). In 2004, The National Sleep Foundation surveyed parents of children up to age 10. The 2026 edition returned to children and families, covering ages 0 to 13.

The NSF surveyed 977 parents and caregivers in English and Spanish around September 2025. The sample included 53% biological mothers, 33% biological fathers, and 14% other caregivers (i.e., step-parents, grandparents, aunts, and uncles). The children are represented four age groups: 206 under 1 year old, 320 ages 1 to 2, 207 ages 3 to 5, and 244 ages 6 to 13.

All of these data are based on parent report. Parents are not always in the room when a child falls asleep, and they are not there when the child wakes at night without making enough noise to alert them. Every number in this poll reflects a subjective estimate.

The Commonly Referenced Standards for Sleep Durations

In 2015 and 2016, two independent organizations reviewed the evidence as perceived by sleep experts. The National Sleep Foundation convened 18 experts who reviewed 312 studies. The American Academy of Sleep Medicine assembled 13 experts who reviewed 864 studies. Three of five shared age groups got identical ranges. Where they differed, the gap was one hour.

The National Sleep Foundation’s 2026 survey data used the Hirshkowitz and colleagues (2015) ranges as the benchmark when they surveyed 977 parents. They asked: How much sleep does your child need? At every age group, the average parent estimate fell below the recommended range.

Because parents are not familiar with the recommended sleep ranges, it may be one factor leading to children not meeting the age-based sleep recommendations.

In Addition to Parents Underestimating How Much Sleep is Needed, Parents Overestimate their Child’s Sleep when Compared to Objective Measures (i.e., actigraphy).

From Prokasky and colleagues (2019), parents overestimate how much their young child sleeps. When 185 toddlers wore wrist actigraphy devices for two weeks, parents overestimated their child's sleep by 2 hours and 10 minutes per night.

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I had the rare opportunity to write a chapter with my wife, Dr. Nicole Rodriguez, on Pediatric Sleep: A Behavioral Account.

While writing, Dr. Derek Reed suggested we co-author and independently publish a children’s book to support parents. A bedtime book that could help parents peacefully complete the bedtime routine and initiate sleep in the desired location without extensive negotiation seemed to fit the mission.

So, we have been deep in designing and crafting a children’s book that has several evidence-based strategies built into the book itself. We have not found another children’s book that takes this approach, which requires specialty printed features.

We have partnered with Melinda Martin as our publishing consultant and editor (and all-around solution finder). She has been a perfect it. Three weeks ago we officially partnered with the illustrator, Gary Wilkinson, to bring Sleepy Star: Bedtime by the Book to life.

One of the first steps for Derek and myself was to try to make some sense of the economics of our decision to independently publish a self-help tool for parents as a children’s book.

In response, we built a calculator in an attempt to predict cost, revenue, and profit. We built ways to toggle the type of sales channel (e.g., Direct, Amazon, Distributor, etc.) and fulfillment provider (e.g., Amazon MCF, Acutrack, Fulfillrite, etc.). In addition, we attempted to take into account all the expenses associated with the initial costs of creating the book and costs as more books are printed and sold.

We know there are likely errors in the calculator, and it was built around the idea of an 8 by 8 hardcover children’s book.

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I have been inspired by people who talk about the journey of publishing while trying to help people, such as Jonathan Goodman, Alex Wiechowski, Ben Putano, and Paul Millerd. As such, we created a generic version of the calculator in case it could help anyone else in a similar position.

Here is a link to the Book Calculator on the web.

If you find value in it or want to make modifications, here is a link to download the HTML file here.

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I am Dr. Kevin Luczynski, a behavioral scientist helping families with sleep and challenging behavior. Co-authoring Sleepy Star: Bedtime by the Book with Dr. Derek Reed. Equal parts bedtime story and bedtime tool for parents — one book that handles the routine, the goodnight, and staying in bed. Follow our journey of directly publishing this book — plus notes on sleep science and behavioral parenting — by subscribing to Atomic Parenting on Substack.

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