The Sleep Question That We Can Put to Rest

“Is the baby sleeping through the night yet?”

It’s always the first question new parents hear when returning to work or introducing their little one to friends and family. The phrase ‘sleeping through the night’ can be anxiety-provoking to new parents. Not only are they likely not experiencing five-hour stretches of consolidated sleep (the definition of ‘sleeping through the night’), but parents may also fear that something is wrong with their baby if they aren’t sleeping all night by a certain age.

There is clearly a mismatch between societal expectations for infant sleep and normal biological infant development. Having an awareness of infant development and realistic expectations for infant sleep before baby arrives is crucial for helping new parents recognize that there is a wide range of ‘normal.’

Infant and toddler sleep cycles differ greatly from those of adults; newborn sleep cycles last an average of 45-50 minutes, whereas adult sleep cycles are closer to 90 minutes[i]. Older children and adults who have reached sleep maturity link several sleep cycles together, whereas a newborn baby is likely to wake after each sleep cycle. This is for good reason, as the tiny tummy needs to be filled frequently in early weeks. But even after the first few months, recurrent night-waking is NORMAL and protective, as it helps prevent baby from slipping into a deep state of sleep where arousability can be compromised. Unlike adults who spend only about 20% of the sleep cycle in light sleep, newborns spend as much as 75% of sleep in light, active sleep[ii], which may appear restless and sound noisy. Nonetheless, this sleep is critical for proper brain development and is not a sign that your baby isn’t getting good sleep. As counterintuitive as it seems, this is the desired state of sleep for healthy development!

What is healthy for infants is likely exhausting for parents; I often say that babies don’t have a sleep problem – but their parents do! The circadian rhythm is not inborn. It begins to develop around eight weeks[iii] but is not well established until around month three or four for full term infants[iv]. This means that babies may sleep more during the day than at night, but know that this stage is temporary as development progresses. To promote the development of the circadian rhythm, expose baby to bright sunlight during the day (getting outside in fresh air for 15 minutes helps), and do not darken the daytime sleep environment.

Perhaps the biggest takeaway for understanding infant sleep is knowing that infant sleep is not linear – meaning even if the baby has five hours of consolidated sleep for a month straight, the next month might be marked by night-waking every hour or two. This may be the case well into the second or even third year for some babies. Attaining sleep maturity, or the linking of several sleep cycles together for a longer stretch of consolidated sleep, is a biological (hormonal, emotional, and neurological) process, not a parenting or behavioral issue. Infant and toddler sleep is impacted by developmental milestones, growth spurts, changes at home (parent returning to work, new daycare, change from bassinet to crib, etc.), teething, illness, travel, and separation anxiety, just to name a few! One longitudinal study found that night waking continued throughout the first year for the majority of infants (58% at 9 months and 55% at 12 months),[v] and there is a wide range for when babies first start consistently sleeping through the night.[vi]

“Perhaps the biggest takeaway for understanding infant sleep is knowing that infant sleep is not linear – meaning even if the baby has five hours of consolidated sleep for a month straight, the next month might be marked by night-waking every hour or two.”

 

Our fast-paced, productivity-focused society places a high value on early independence, but this does not align with babies’ primal mode of operation. Their biological development has not adjusted to modern day demands, and nor should it as night-waking is both normal and protective. Infants don’t even recognize that they are separate beings from their primary caregiver until around roughly seven months. Babies need care around the clock, and their reasons for waking at night vary.

Besides waking for hunger, babies and toddlers often need the warm and comforting arms of their parents to help them settle back to sleep. ‘Self-soothing’ is a term mentioned frequently in baby sleep books, and this is cited as a skill babies need to learn on their own to achieve independent sleep. However, neuroscience shows that infants are not developmentally capable of emotional regulation. The part of the prefrontal cortex where executive functioning and rationalization originate doesn’t develop until late preschool years, and it isn’t fully functioning until early adulthood. For those babies who do settle back to sleep easier and don’t require as much nighttime parent involvement, it is likely a reflection of baby’s unique temperament and personality. Babies who are more sensitive will tend to have more fragmented sleep and need parental comfort at night (these babies are not likely to do well with being put down ‘drowsy but awake’). This doesn’t mean that they are a difficult or ‘bad’ baby! Changing our mindset as to how we view these nighttime disruptions is half the battle.

The transition to sleep is one of the most vulnerable and difficult times for a little one. The more parents can positively assist children with this transition and help create a healthy attitude toward sleep, the easier the process will eventually become. The development of emotional regulation takes time, and until then, parent co-regulation is invaluable. The process cannot be rushed, and every baby develops at his or her own pace. Knowing this from the start of parenting can help with setting realistic expectations, help parents view the experience through the eyes of their children, and reduce the stress from worries that their baby isn’t normal.

As for fielding all those questions about how the baby is sleeping, try the response, “Like a baby.”

[i]Jenni, O.G., Borbely, A.A., Achermann, P. 2004. ‘Development of the Nocturnal Sleep Electroencephalogram in human infants. Journal of Physiology – Regulatory, Integrative, and Comparative Physiology, 286: R528-38.

[ii]Poblano, A., Haro, R., Arteaga, C. 2007. ‘Neurophysiological measurement of continuity in the sleep of fetuses during the last week of pregnancy and in newborns,’ International Journal of Biological Science, 4 (1): 23-8.

[iii]Antonini, S.R., Jorge, S.M., Moreira, A.C. 2000. ‘The emergence of salivary cortisol circadian rhythm and its relationship to sleep activity in preterm infants,’ Clinical Endocrinology, 52 (4): 423-6.

[iv] Mirmiran, M., Maas, Y.G., Ariagno, R.K. 2003. ‘Development of fetal and neonatal sleep and circadian rhythms,’ Sleep Medicine Reviews, 7 (4): 321-34.

[v] Scher, A. 1991. ‘A longitudinal study of night waking in the first year,’ Child Care Health Development, 17 (5): 295-302.

[vi]Wooding, A.R., Boyd, J., Geddis, D.C. 1990. ‘Sleep patterns of New Zealand infants during the first 12 months of life,’ Journal of Pediatric Child Health, 26 (2): 85-8.