Source: BASIS Co-Sleeping Image Archive

 

One of the stressors that many new parents face is the question of whether or not their baby or child is sleeping enough.  We are bombarded with information about how important it is to get enough sleep and it can seem like the consequences are dire if we don’t reach this.  Despite the dire warnings, I actually believe that the information we do have should serve to calm parents, not stoke any fears.  As such I hope to review this information here in hopes of alleviating concerns on your own child’s sleep.

Average sleep times

Regardless of what study we look at, one thing is abundantly clear: Sleep in infancy and toddlerhood is hugely variable.  This means that it is nearly impossible to really define what constitutes ‘enough sleep’ likely because it is so different from one child to the next.  What kind of variability are we talking about?

  • One study out of Zurich included 493 children who were followed from birth for 16 years of age
[1]. Numbers were provided by percentile with the 2nd and 99th percentiles being included (along with others in between).  At one month of age, the range of total sleep (night + day) was approximately 9 hours (2nd percentile) to 19 hours (99th percentile).  By 6 months, this range had only narrowed to approximately 10.5 to 18 hours in a 24-hour period, by 1 year the range was 11.25 to 16.5 hours, and by 2 years it had only reduced to 11 to 16 hours.  Nighttime sleep was equally varied with a range of 6 to 13.25 hours at 1 month then having night increase up to one year where the range is 9.5 to 13.5 hours (2nd to 99th percentiles).  Notably, these numbers are likely inflated as the means used to assess sleep was simply bedtime and wake time.
  • A study using app data from 841 children around the world[2] found ranges for nighttime sleep of approximately 6 to 12.5 hours of sleep at 1 month, approximately 6 to 14.25 at 1 year, to approximately 7 to 12.5 at 2 years of age. Daytime sleep was also variable with ranges of approximately 0 to 4 hours a day at 1 month, 0 to 3 hours a day at 1 year, 0 to 3.5 hours a day at 2 years.
  • A meta-analysis of sleep duration across childhood[3] found a range of 9.7 to 15.9 hours in infancy and 9.9 to 13.8 hours in toddlerhood.
  • There are actually plenty of other studies that all find the same thing: huge variability.  So why do we hear that our children must reach a certain number of hours?  It’s unclear.  What you should know is that these hours are based on averages, not any research that shows that number is magical.

    What affects sleep?

    Outside of child-level factors that we just don’t know all of, there are things that can impact sleep and though we may think of these as being ‘bad’ because they may be associated with shorter sleep durations or more wakings, we need to be careful how we interpret or consider the evidence.

    • Research has highlighted that breastfed babies tend to wake more frequently and have a shorter longest stretches of sleep (e.g., [4],[5]).  This often leads families to mix feed or cease breastfeeding altogether.  However, families should know that although there is a relationship early, it disappears later and is not associated with total sleep duration[6].
    • This one is more mixed with some studies suggesting that bedsharing or co-sleeping is linked with more wakings (e.g., [4]), whereas others have found no relationship (e.g., [5]).  Parental reports can also go both ways with some families saying co-sleeping saved their sleep while other report that they sleep worse with it.
    • Total sleep varies by culture.  Specifically, Western cultures expect and create routines around greater sleep than Asian cultures.  In the systematic review of sleep patterns [3], Asian cultures were found to have children with over an hour’s less sleep per day on average than children in Western cultures.  This is likely due to the more regular practice of co-sleeping in which all family members go to sleep at the same time.

    Now, it is important to consider that while some of us may worry that more sleep is what we should be looking for, we actually need to consider these factors through an evolutionary lens.  The reality is that bedsharing and breastfeeding – or breastsleeping[7], as it is known – are the more biologically normal experiences and thus the sleep that is gotten with them should be seen as what is more normative for our species.  This does not mean that more sleep is bad or that it may even be better and that sleep was a trade-off for other benefits that have served us well, but it is the norm and thus we need to compare outcomes according to these norms.

    Conclusions

    The main purpose here is to highlight that every bit of research we have may come up with an average value of sleep, but that this average is surrounded by HUGE variability.  When you think about your infant’s sleep – too much? too little? – you have to make sure to realize that actually what constitutes ‘normal’ is a very large range of numbers.

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    [1] Iglowstein I, Jenni OG, Molinari L, Largo RH.  Sleep duration from infancy to adolescence: reference values and generational trends.  Pediatrics 2003; 111: 302-307.

    [2] Mindell JA, Leichman ES, Composto J, Lee C, Bhullar B, Walters RM.  Development of infant and toddler sleep patterns: real-world data from a mobile application.  Journal of Sleep Research 2016; 25: 508-516.

    [3] Galland BC, Taylor BJ, Elder DE, Herbison P.  Normal sleep patterns in infants and children: a systematic review of observational studies.  Sleep Medicine Reviews 2012; 16: 213-222.

    [4] Huang XN, Wang HS, Chang JJ, Wang LH, Liu XC, Jiang JX, An L.  Feeding methods, sleep arrangement, and infant sleep patterns: a Chinese population-based study.  World Journal of Pediatrics 2016; 12: 66-75.

    [5] Figueiredo B, Dias CC, Pinto TM, Field T.  Exclusive breastfeeding and three months and infant sleep-wake behaviors at two weeks, three and six months.  Infant Behavior and Development 2017; 49: 62-69.

    [6] Pennestri M, Laganiere C, Pokhvisneva I, Bouvette-Turcot A, Steiner M, Meaney M, Gaudreau H.  Sleep patterns as a function of breastfeeding: from infancy to childhood.  Sleep 2018; 41 supp 1: A98.

    [7] McKenna JJ, Gettler LT.  There is no such thing as infant sleep, there is no such thing as breastfeeding, there is only breastsleepingActa Paediatrica 2016; 105: 17-21.