The ups and downs of normal infant sleep 

If you’re a parent of young children, you’ve probably already noticed that sleep doesn’t improve in a straight line from the day your tiny person is born! In fact, sleep patterns may vary considerably over the first two years of life, with relative calm often followed by phases of frequent waking. These ups and downs reflect the many periods of rapid growth and development seen in the first few years. Sleep patterns reflect brain maturation and stages of development [1], and this may be seen in your baby’s increased need for your support at night. 

There’s no doubt that this is a tiring season, and many of us become obsessed with finding ways to help baby sleep better. But although night wakings can feel demanding or exhausting at times, it doesn’t mean that your baby has a “sleep problem”. Night wakings in babies are normal and important, promoting valuable nighttime feeds and connection [2,3] and regular arousals from deep sleep, which are thought to protect from Sudden Unexplained Death in Infancy (SUDI)[4,5].  

How we react to our baby’s sleep is also influenced by our knowledge and expectations [6,7]. Modern life and our culture often conflict with biologically normal infant sleep, making it harder for parents to manage night wakings. From an evolutionary perspective, babies are programmed to expect to breastfeed all night in close proximity to their mother, but this isn’t always easy given the way we live now.  

Read more about normal infant sleep

But here’s the secret to not only surviving but thriving:

  • Learning to roll with these intense periods in the knowledge that they soon pass
  • Accepting that your baby isn’t broken - this is hard but normal!
  • Maximising your own sleep and wellbeing, while supporting your baby’s needs. 

Feeling overwhelmed? Here are some tips to help you cope

Let’s consider night wakings further. If you’re like most tired parents, your main concern is the magical threshold at which your baby sleeps for longer periods without waking. In fact, like adults, all babies wake regularly throughout the night, moving through sleep cycles and rousing at the end of each one. What can disrupt a parent’s sleep is whether they cry out. Most babies cry for a parent’s help when they rouse after sleep cycles, needing feeding, rocking or a cuddle to move into the next cycle. But as you’ve probably noticed, some babies are able to go back to sleep without a parent’s help. 

Why is this the case?

A baby’s temperament and any health issues can influence whether they will cry for a parent during their night wakes. Some babies with a calm temperament can link sleep cycles alone from a few months of age, but they are a minority and can’t be the standard to which we compare all infants. For babies with a more intense temperament, reaching this stage will often take much longer! Where there is a true medical or developmental problem affecting sleep, this can be very stressful, so it’s important that you can access sensitive evidence-based medical advice.  

Could your baby's sleep be abnormal?

So why does some research suggest that all babies should all be able to sleep through from around 4-6 months of age? Studies may not tell the whole story. For example, almost all of the early studies that aimed to establish what was “normal” were based on formula-fed infants, who have quite different sleep patterns to breastfed babies [8]. And many modern studies rely on parent reporting of night wakes, which has been shown to be an unreliable way to determine sleep patterns [9]. 

The simple fact about infant sleep is that most children will need loving parental support during the night well into toddlerhood. It’s worth remembering that sleeping with a parent is normal in almost all human cultures, and that babies and young children (like all mammals) are biologically wired to be close to their family at night. 

Our experience with families in the Beyond Sleep Training Project is that many new parents are not sure what is normal for their baby’s sleep and often agonise over their baby’s night waking, or their need to be fed or rocked to sleep. Unfortunately, an outdated understanding of infant sleep persists in healthcare and in our culture, reinforcing the idea that night waking is abnormal or even harmful. Understanding and gaining acceptance of what is normal can lead to a much more positive outlook on your baby’s sleep, and help you focus on making the most of this precious time. 

“Your baby is a unique little human, and they will sleep through when they are ready. Freeing yourself of the idea that they should be sleeping through by a certain age means you can focus on what matters: Maximising your wellbeing, and being present to fully appreciate your beautiful baby as they grow.”


Sleep development during the first two years

Newborn to three months 

The first few months are a whirlwind of sleepless nights and unpredictable days as your baby gets used to the world outside their mother’s body.  After the newborn fog clears, most babies start to establish their circadian rhythm, or “sort their days from their nights”.  Sleep stretches get longer and the 3-month mark may actually see the best periods of sleep in the whole first year! However, what comes after this period are many phases of intense development that can affect sleep.

Read more about your newborn baby

4- 6 months

Parents are often surprised when their baby starts suddenly waking again around four months after starting to sleep for long periods. You may have heard this called the “four-month sleep regression”, but in fact, this is the first key period in which babies’ sleep cycles start to become more like those of adults [10]. “Sleep progression” is therefore a more fitting and positive term! The change to sleep cycles of 90 minutes’ length can cause frequent night wakes, and sometimes difficulty with falling asleep. Your baby may also want more closeness, rocking or feeding as they emerge from the fourth trimester and start to recognise that you can physically separate from them. 

8-10 months

Another common time for sleep disruption is the 8-10 month period. This may relate to rapid brain changes due to the development of locomotion (learning to crawl, pull up and walk) [9-11]. Many babies are also teething at about this time, and a number of other developmental changes are occurring such as language acquisition. Practically, this may mean that you need to try different strategies to help your baby find sleep. After almost a year of parenting, this can be an exhausting period, but it passes quickly. Most importantly, there are lots of ways to help both you and baby get the sleep you need.  

12-18 months

There can be some improvement in sleep after 12 months, but it may still be up and down. Recent research has found that only around 56% of babies sleep through for 8 hours at 12 months of age [12]. In this study, the babies that woke at night were developing just as well as the babies that slept through. Although babies do need more total hours of sleep than adults, there is very little evidence to support the idea that babies need uninterrupted sleep. The 18 month period often sees a language explosion, and it is probably not a coincidence that many parents notice further sleep challenges at this time. 

18 months - 2 years

Other common events that may affect sleep are the birth of a younger sibling and learning to use the toilet. Just like adults, babies and toddlers find big life changes challenging, and some disruption to sleep is likely. In addition, daytime separation from parents (such as when babies attend daycare) at any time during the first few years may cause babies to wake overnight. This is known as “reverse cycling” and may be common in breastfed babies, who often feed at night for both calories and connection if they are separated from you during the day [13].  

Contributed by: Dr Shireen Durrani, MBChB, MPP, MPH, FAFPHM, Little Sparklers Director
Banner image credit: Vida Images

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REFERENCES:

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8. Bartick M, Tomori C, Ball H. Babies in boxes and the missing links on safe sleep: Human evolution and cultural revolution. Maternal and Child Nutrition 2018; 14: 2. 

9. Rudzik A, Robinson-Smith L, Ball H. Discrepancies in maternal reports of infant sleep vs. actigraphy by mode of feeding. Sleep Medicine 2018; 49: 90-98

10. Louis J, Zhang JX, Revol M, Debilly G, Challamel MJ. Ontogenesis of nocturnal organization of sleep spindles: a longitudinal study during the first 6 months of life. Electroencephalogr Clin Neurophysiol. 1992 Nov;83(5):289-96. doi: 10.1016/0013-4694(92)90088-y. PMID: 1385085.

11. Atun-Einy O, Scher A. Sleep disruption and motor development: Does pulling to stand impact sleep-wake regulation? Infant Behaviour and Development 2016; 42: 36-44.

12. Pennestri MH et al. Uninterrupted Infant Sleep, Development, and Maternal Mood. Pediatrics 2018; 142 (6) e20174330

13. La Leche League UK website. If you leave your baby. https://www.laleche.org.uk/if-you-leave-your-baby/. Accessed 10 July 2020.