I’m often inundated with questions about sleep in the 6-12 month age group. This is a fascinating stage, with so much development. It’s also, I think, a really difficult age because many people expect that their child will be sleeping through by this point. Societal, peer, and health professional expectations are often at odds with what is biologically normal. Parents can therefore often feel like they are getting it very wrong.

There are also a lot of other misconceptions. I want to talk about 2 main ones today:

1. Firstly, there is the idea that sleep is a developmental milestone, and children will gradually work towards it, and the older they get, the more likely they are to achieve this milestone.

2. Secondly, there is a widely held belief that once a child has achieved this important milestone, that they have sort of ‘cracked it’ and no more will they wake at night as a general rule.

I was digging into this lately, as these misconceptions don’t fit with what I see in clinical practice and from the thousands of families I support. I wanted to know if I had any science to back me up on this. Well, friends, turns out, someone has researched this, and it’s interesting, and validating.

In a recent issue of Sleep Medicine, Marie-Helene Pennestri and colleagues wrote up their research looking at the variable nature of sleeping through the night (STTN) which in this study was defined as 6 hours straight among infants at 6 months of age. They first of all acknowledged that this is a subjective term, and noted a number of problems, including the fact that STTN is sometimes defined as 5 hours, and sometimes 10-12. They also noted that in some studies, there is an ever/never classification of STTN – which means that even if an infant slept through the night once during the study period (using whatever definition of STTN that the researchers used) they were counted as having slept through the night as a kind of binary concept, even if it didn’t happen again for another 6 months.

Pennestri found that infant sleep was highly variable between 8-14 months – which fits with what I observe, and noted that it tends to be especially variable at key developmental stages. It is variable between infants, and within infants. This means that infants vary between each other in terms of their longest stretch of sleep, but they also vary from night to night within the same infant. There were more wake ups at 12 months than at 6 months, which flies in the face of the commonly held belief that sleep gradually gets better with age.

Notably though, what they also found was that there was a huge range in their sample of the longest stretch of consolidated sleep, between just over 2 hours, to over 10 hours. They found that 20% of infants never slept through the night (6 hours), and only 6% always did. The rest had highly variable sleeping patterns. 40% of the babies in the sample slept through the night for 5 out of 13 nights, but the rest were much less consistent than this.

The takeaway point here is that if a baby sleeps through the night, this does not mean they’ve cracked it. It is likely to continue to have variability, especially around key developmental stages.

Interestingly, Sleep Medicine is not a fluffy, responsive-parenting friendly journal as a rule, so the findings are even more meaningful to me, in a journal that usually promotes behavioural sleep training.

It’s significant because many sleep research articles are using the ever/never definition, and therefore the number of children who STTN may be significantly less if a more realistic definition was used. This would be very likely to alleviate anxiety around consolidated nighttime sleep for parents.

The study is useful as an expectation check. The myth that 6 months is some kind of magic age for cracking sleep is unhelpful as it leads many parents to feel that their child simply didn’t get the memo, or that if they haven’t started sleeping now, they’re basically screwed. It piles on yet more pressure when the truth is that you can’t fix normal. The takeaway from the study was that 6% of 6-month olds sleep 6-hours straight. All the sixes. Nice and easy to remember. And also – important to share far and wide to prevent parents the world over feeling they like their baby is a sleep delinquent.

If you need more support with infant sleep, check out my second book Let’s talk about your new family’s sleep, and also my Responsive sleep support class.

Lyndsey Hookway is a paediatric nurse, health visitor, IBCLC, holistic sleep coach, PhD researcher, international speaker and author of 4 books. Lyndsey is also the Co-founder and Clinical Director of the Holistic Sleep Coaching Program, co-founder of the Thought Rebellion, and founder of the Breastfeeding the Brave project. Check Lyndsey’s speaker bio and talk brochure, as well as book her to speak at your event by visiting this page. All Lyndsey’s books, digital guides, courses and webinars can be purchased here, and you can also sign up for her free monthly newsletter here.