Sleep Training Part 2: Sleeping Through the Night


Sleeping Through the Night by 4 months

This blog is a continuation of last week’s blog, where I break down the science that is covered in Stephanie Liu’s article “Why Sleep Training Won’t Hurt Your Child”. Stephanie’s article is published in an online blog called, which states that it is “academic rigour” with “journalistic flair”. I hope you will begin to see why that tag line is not very accurate, and that the article, with it’s references to research, has the potential to pull parents off the mark when it comes to evidence-based support of their infant’s sleep.

Henderson’s 2010 article “Sleeping Through the Night: The consolidation of self-regulated sleep in the first year of life”, published in Pediatrics, looked at consolidated sleep (sleeping longer periods of time without having a long awake period) and self-regulated night-time sleep (rousing, and falling back asleep without parent support). These two skills (consolidated sleep and self-regulated sleep) are two biggies for babies and for parents. They are developmental skills that are impacted by physiology (neurodevelopment and maturation) and the environment around a baby. They represent what most tired parents covet: a better night’s sleep for us! This study looks at when, developmentally, babies (in a sample of 75) tend to consolidate sleep.

Consolidated sleep and self-regulated sleep are two biggies for babies and for parents. They are developmental skills that are impacted by physiology and the environment around a baby.

The researchers followed 75 typically developing babies for 12 months. Moms filled in a diary 6 days per month, and her diary was validated against videosomnography (videotaping sleep). The researchers wanted to know at what age the babies in their study: (1) slept from midnight to 5am, (2) slept 8 hours straight, and (3) slept from 10pm to 6am. That last one, 10pm to 6am, was called “family congruent” sleep: sleeping during an 8 hour period when we as parents would typically want to be sleeping too. It hadn’t been studied before, and represents an attempt to look at sleep from a practical point of view (the midnight to 5am period was randomly chosen by earlier researchers for no particular reason).

What Henderson and her colleagues found was that the largest increase in self-regulated sleep length happened between one and four months of age. Those who have wee ones will generally notice this shift (despite you still being tired): it represents maturation, and it does look and feel different than the sleep of a newborn. At 2 months, many babies in the study were sleeping from midnight to 5am. At 3 months, many babies were sleeping for 8 hours. And at 4 months, many babies were sleeping 10pm to 6am. The researchers concluded that two and three months of age is the most likely age for “sleeping through the night”.

Twenty-eight percent of 12 month olds were not sleeping 10pm to 6am either. That’s helpful to know.

The researchers also pointed out that at 12 months, 15% of the babies in their study were not sleeping midnight to five am, and were not sleeping 8 hours. That’s not an insignificant number. If you have a one year old that is not sleeping through, you are not the only one! 28% of 12 month olds were not sleeping 10pm to 6am, either. That’s helpful to know.

What the study does not point out, though we know well, is that sleep is not a straight trajectory: sleeping through at 3 months does not mean sleeping through at 9 months. Parents who connect with me when their babies are 9 months old are experiencing this!

Ultimately, this study helps us understand that we can expect that the most rapid consolidation of sleep regulation will happen in the first 4 months (without us doing a thing), and that if babies are experiencing really challenging sleep over that time, it is worth exploring what may be getting in their way.

Henderson’s study does not suggest that babies who are unable to sleep through the night at four months need to be “trained” to do so.

What this study does not help us understand is why some babies do not meet these sleep criteria by four months. This study also doesn’t suggest that if babies are not meeting these criteria they need to be ‘trained’ to do so.

What does this mean for parents? It means that:

  1. You can expect big shifts towards consolidated sleep and longer stretches of sleep at night in the first 3 or 4 months;

  2. Even though this shift is expected, it may not feel like you are well rested during these early months. Sleep interruptions are still common, especially when we add in illness, prematurity, reflux, early teething, tummy troubles, and other interruptors;

  3. If you are feeling like your baby is waaaay off course for sleep consolidation, you do not need to teach the skill through sleep training. A more helpful approach may be to sleuth out what may be getting in their way while still meeting their needs for support from a loving parent. It may be reassuring to know that even if most babies are consolidating sleep, not all babies are, and it does not mean that something is wrong. If mama gut or other factors raise your concern, reach out.

  4. In the meantime, your responsive, reflective parenting will provide your baby (and you!) with the sense that needs (physical and emotional) are being met;

  5. You have needs too! Building a village of support can be tricky and yet the value of it (a neighbour’s daughter visiting as a mother’s helper, asking your mom to come by, and finding a mom friend who can relate to the challenges, as well as valuing your own needs for sleep and for connection) can be felt so deeply. Look for your supports. To borrow words from Mr. Rogers, “look for the helpers. There are always helpers”. If support from me through this process would be helpful to you, I would be honoured to be part of your village.

Next week I will be reviewing an article about a five year follow-up study on the harms and benefits of behavioural sleep intervention.