One of my students was recently listening to a webinar in which the presenter claimed that it was the number of night wakings that was important at night, rather than the total sleep duration. Given that this is at odds with what many of us in the responsive sleep space understand from sleep biology and the available literature, this confused her, and she reached out to the presenter who provided the requested literature to evidence this bold statement. The presenter duly provided a reference list, and my student sent them along to me to peruse.
This is not the first time someone in the mainstream sleep world has claimed this association of poor behavioural/cognitive outcomes with more frequent night wakings. It’s problematic because of course the usual follow up advice if a child is perceived to be waking an excessive number of times is to reduce these wake-ups, often with a non-responsive behavioural style of sleep training.
I want to be clear that the distinction in this case is that the drive to reduce the wake ups is not parent-led, but researcher/sleep trainer led. Of course my personal approach is to support all parents who are genuinely struggling with sleep to find sustainability. But that’s not what this is about. It’s about an attempt to pathologise night waking under the misguided belief that it is somehow harming infants’ development long term.
Let’s first think about what constitutes problematic sleep. This is actually the first discrepancy we have, because most sleep researchers and sleep trainers use the Avi Sadeh (2004) classification of sleep in 6-30 month old children which warrants a referral for intervention, which is:
1. More than 3 wakes per night
2. Spends more than 1 hour in wakefulness in the night
3. Achieves less than 9 hours of total sleep in 24 hours
What I find slightly tricky about this classification is the frequency of waking. I totally agree that more than 3 night wakes is hard work, but does it require intervention as a standalone criteria? I also have a problem with 6-month-old babies having the same referral criteria as 30-month-old toddlers. The Hysing study (2014) that I often quote found that 70% of 6 month olds wake 1-3 times per night, with 20% waking more than 3 times per night. The Brown and Harries (2015) study of 6–12-month-old babies found that nearly 80% were waking at night. The average number of wake ups was 1.77, but the range was 0-7. So it’s clear that night waking is pretty common.
The issue is whether something so common can sensibly be classified as pathological. Whenever a significant proportion of a population are doing something, to me, that always sounds pretty normal. Hard, yes, but probably within a normal range. Nevertheless, this is the criteria for ‘problematic’ sleep requiring intervention according to someone who is often cited as a highly influential sleep researcher.
Next, what is the rationale for suggesting that the number of night wakes is more significant than the total 24-hour sleep duration? Well, more frequent night waking in 6-month-olds does seem to be predictive of more night waking at 18 months in the Hysing study, though other studies find that generally, night waking reduces over time. But are there any other reasons for suggesting that night waking in and of itself is harmful, outside of an underlying problem causing the night waking (which obviously is different)?
Often, sleep trainers will claim that night feeding deprives little ones of sleep, but this is not a sound rationale, because infants and young toddlers feed during sleep, and if responded to promptly, will rapidly return to sleep, even if they are feeding simultaneously. There is a big difference between a child waking at night being unsettled and wakeful, and a child who promptly returns to sleep when comforted.
The two studies provided in this instance as evidence that more frequent night waking is linked with later development of problematic emotional, behavioural and neurodevelopmental outcomes were the Cook et al (2020) the Cook et al (2021) studies.
The 2020 paper is an Australian longitudinal study which uses parental report of problematic sleep with no objective corroboration of the waking patterns, and lacks ethnic and socioeconomic diversity. Essentially, the infants with more unsettled sleep patterns were more likely to be diagnosed with emotional disorders, but not psychiatric disorders. It’s very important to note here that these diagnoses were not formally given, but were agreed on the basis of parental report of behavioural criteria. This computerised data was then analysed by psychologists and grouped into various classifications of disorders. Obviously this has potential for bias and inaccurate diagnosis – both over reporting and under reporting of pathological findings. One other interesting aspect of this study was that more unsettled infants had more problems with separation anxiety at age 10. This may suggest that those infants needed more co-regulation from their parents because they had more anxious/sensitive temperaments. However, one of the problems is that because this study relied on parental reporting of infant characteristics, there was no objective assessment of attachment style, which would have been interesting.
The 2021 paper explores the association between regulatory problems in the first year, with language and communication challenges at age 5. One of the first problems with this is that sleep, crying and feeding problems are collectively labelled as regulation challenges. The researchers suggest that difficulties with regulation in the first year are at ongoing risk for dysregulation later in childhood. Once again, this cohort study used parental report of feeding problems. Interestingly there was no input from lactation specialists, or speech and language therapists in infancy even though many of the feeding challenges named (such as choking, gagging, inability to tolerate pureed or lumpy foods) under regulation problems clearly would be an indicator for referral to IBCLC or SLT (or both). The children were seen by SLT at age 5 and 11 years. Essentially, the study found that severely unsettled infants had a greater likelihood of language difficulty at age 5.
Where I get frustrated with this study being used to back up the theory that more waking is more problematic is that when you break the data down, having unsettled sleep without the other measures of ‘dysregulation’ (feeding and crying challenges) was NOT associated with poorer language development. It was only the children who were unsettled across the whole spectrum of dysregulated behaviour who were at risk.
With both of the studies, I want to stress that they clearly demonstrate that some parents are having a really hard time with their dysregulated infants, and these infants seem more likely to go on to be diagnosed with a language, behavioural, neurodevelopmental challenge. But there is absolutely no evidence that the poor sleep is causative. The poor sleep may well be a very early indicator of a more global challenge (in the context of other difficulties with settling and regulation) but there is no suggestion, even from the researchers, that poor sleep or more night waking causes these problems.
So why are they being used to claim that there is? It’s not the first time my friends, and it probably won’t be the last. I stress that I’m not necessarily criticising the studies. No study is perfect and there are problems with most data collection. It’s easy to pick holes in a research study you haven’t spent years designing, implementing and analysing. No, what I take real issue with is the perpetual use of related research to attempt to back up a claim that the paper isn’t making.
So let me say it one more time for those at the back. There is no evidence that frequent night waking causes long term emotional/cognitive/behavioural/neurodevelopmental problems.
I’m not suggesting that we shouldn’t support parents who are struggling. But let’s not worry unduly about night waking unless it’s problematic for a family. Sleep training should never be suggested to ‘prevent’ future problems or scare parents into believing that if they don’t address their child’s sleep, it will cause future challenges. That’s just BS.
If you need sensible, up to date information about sleep biology and how to support sleep without sleep training, check out the Holistic Sleep mini course, and if you’d like a really deep dive, the Holistic Sleep Coaching Program.
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