Sleep disturbance and motor development

 

It’s a common enough situation. A parent brings their little one to the practice for a milestone check because little johnny or lucy has started crawling, standing or walking and mom and dad want to make sure its all going well and the progression is developmentally where it should be. during the history one of the issues that comes up is broken sleep. Often we are presented with these kiddies that have mastered the art of sleep months ago only to now start experiencing these longer awake times at night for no discernable reason. They aren’t sick, their food intake is adequate and they are thriving in all other facets of life, however it looks like sleep is regressing  This, of course, can often be quite worrying for parents because they were getting used to unbroken sleep again and now they feel they back to square one. And a child moving back to frequent night waking in the night is generally a red flag to a parent that something is wrong and needs to be addressed. Clinicians will look to aspects like illness, nutrition, behavioural issues or possibly even poor biomechanics for the manual therapists out there to explain these unexpected wakings…but what if there is another, more deep seated reason behind this phenomenon behind this observed sleep issue in conjunction with developemental milestone achievement?

 

To help answer this question, we’re going to turn initially to the authors Scher and Cohen who published a study called: “Sleep as a mirror of developmental transitions in infancy: The case for crawling”. This work was published in 2015. Now they had the goal in mind of finding out if these increased long waking periods us as practitioners and parents were seeing were perhaps temporally linked to crawling aquiisition.

 

Before we get into their findings lets get some background and context into what we are looking at.

 

For infants: uninterrupted, continuous sleep and being able to regulate that transition from awake-to-asleep states is generally happens gradually over the first year of life and it gets better and more consolidated as time goes on. A main focus in the first months of infancy is to establish the circadian pattern so that sleep their occurs at night and they are more wakeful during the day, by 3-4 months the awake-and-sleep states are synchronized with day night cycles thanks, in part, to the appearance of meaningful amounts of melatonin at this time. However, fragmented sleep and night waking still seems to characterize the second half of the first year, and this is a phenomenon has been noted by clinicians, researchers and parents alike. This Re-occurance of disrupted sleep after periods of successful continuos sleep, like they have this down, especially in the absence of disease or malnutrition, almost begs a developmental explanation.

 

Looking in terms of development, the first year of a baby’s life involves attaining a series of neuro-motor milestones and changes in bio-behavioural regulation, with both of these relying on the interplay between brain maturation on the one hand and context dependant experiences on the other. So basically, the way milestones and behaviour develop has to do with how mature the brain is when it experiences what it experiences in the environment.

 

Now, gaining the ability to move yourself, or as the researchers refer to it ‘self-produced locomotion’ is one of the most significant milestones involved in early development of infants. In short, It’s a complete game-changer.  So much so that much research has gone into the relationships between the acquisition of crawling and other facets of development such as: fear of heights, memory retrieval, emotional regulation and seeking proximity of their caregiver.

 

The idea of sleep being affected by crawling has been proposed before this 2015 trial, in fact in a few pieces of work, many of them involving the researcher Anat Scher, with preliminary findings that indeed sleep in crawlers is more disrupted than non crawling peers but results don’t show if the acquisition of crawling contributes to sleep dysregulation or if infants with advanced motor skills, who aquire crawling early are also charaterized by more sleep disruption.

 

The suggestion that the new motor skill might trigger longer and more active night time arousals, stir emotions and anxiety fits with Dahl’s proposed a model from 1996 – stating that “the neurobiology underlying the regulation of sleep overlaps with the neurobehavioural systems involved in the regulation of emotions and behaviour.” The research paper we are focused on here took this to mean that changes in sleep could be  interrelated with advances in other developmental domains. Although little evidence exists around sleep changes and developmental transitions, reduced sleep quality has in the past been noted with pubertal changes and Emde eta l 1976 showed changes in sleep reflect basic shifts in the central nervous system and mirror rapid changes in early development.

 

 

 

Current research followed infants from pre to post crawling stage and looked primarily at long wake episodes. The normative age range for crawling has been shown by previous research to be  5 – 11 months and this is the age group involved in the study.

 

Also wanted to find out if age at which crawling is attained shapes the relationship between changes in motor and sleep variables. Earlier research (Biringen et al 1995) found the effect of crawling on sleep to be more pronounced in infants who start crawling at a younger chronological age. To ascertain this, they broke down into groups of early and late crawlers – not delayed development. WHO states median age for crawling hands and knees is 8.3 months.

 

 

So 28 full temers (small number), looked in every 2-3 weeks, sleep recordings (actigraphy - wristwatch like computerized movement detector provides valid sleep assessment in infants, valid and reliable sleep assessment for infants), sleep diary – motor milestones diary and motor observations

 

Results – ave crawling age was 7 months – not far off from the WHO average, age of crawling onset wasn’t associated with gender and fussiness/difficulty wasn’t correlated to age of crawling or number of long wake episodes.

 

 

Sleep of low risk infants improved significantly from 5-11 months. But this study also captured periods of increased long wake episodes. Study reveals sleep of crawlers was more disrupted than that of same age non crawlers and study reveals a link between locomotion progress and changes in sleep-wake regulation. More sleep interupptions were prevelant once crawling milestone was acquired. So sleep adds to the growing list of behavioural and psychological domains that are functionally and temporally associated with crawling onset.

 

This study also talks about timing – the timing of experiences shapes the development in terms of trajectory and outcomes. By comparing younger and older crawling achievers and showing crawling was a marker of rise in long waking episodes in both groups. Younger achievers showed increase sleep disrtuption from pre-crawl to emergence of the milestone followed by a significant decrease in post crawling phase. Whilst later adopters increase from pre to post crawling period

 

 

To explain the findings, we can again look to dahls model “the neurobiology underlying the regulation of sleep overlaps with the neurobehavioural systems involved in the regulation of emotions and behaviour”. The rise of long wake episodes may accompany the increased regulatory and emotional reactivity seen with locomotion onset. Locomotion dependant emotional arousal and heitened excitement could comprimize childs ability to self regulate back to sleep after a brief night waking. (goes along with Mahlers theory).

 

Could also be developmental reorganization underlying the achievement of crawling involves restructuring of sleep wake states. This leads us to the premise that developmental progress may entail periodic instability in behavioural regulation and behavioural disorganization. There are studies which speak of the Dynamic System Principle which is a: “downward trends in performance and in behavioural control often marking the emergence of a new skill or ability.” This is a pattern that has been seen in crawling acquisition and  manual reaching, vocal production and language acquisition and now thanks to sher and cohen …sleep as well.

 

T Berry Brazelton, who well known for his work in identifying the universal crying curve in infants has a ‘touchpoint’ model which maintains that developmental spurts are periods of disruptions and behavioural reorganizations involving child and caregivers and that sleep is a recurrent touchpoint theme and its disruption during the second half of the first year is tied to the advancement of new capacities such as crawling and standing. You can get hold of the book touchpoints.

 

Limitations

Small sample and so limited power to detect between group differences. But its bigger than other studies looking at infant behaviour interelations with samples of no more than 14 participants.

 

 

 

Another paper I looked at was from Atun – Einy and Scher 2016 called – sleep disruption and motor developemtn: does pulling to stand impact sleep – wake regulation? This study focused on pull to stand and if this new skill also entails disrupted sleep. Pull to stand launches the upright posture. Causing a change in vestibular response and sensitivity to detect movement in the body in planes they have not previously experienced by crawling and rolling. Importantly Pull to stand takes infant out of supine position ( a posture which encourages sleep).

 

Here looking at 20 participants – from 7 to 12 months. Parents given motor diary, actigraphy

Again early and lates -

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Average pull to stand was at 8 months and 20 days.

Again similar between girls and boys

 

Results – again overall sleep consolidation improved over time but again the sleep disruption was observed around the milestone but this time only in infants who pulled to stand during the 7-8 month age window – for kids who achieved the milestone later, sleep consistenly improved through the study. In early group night waking increased with emergence of the milestone. Answer is its possibly age dependant.

Could be because PTS is not as impactful as crawling is. Ramifications of PTS may not be as massive as the crawl changes even tho its such a big milestone for us as parents to see out baby pull itself to standing for the first time.

 

So taking all of this new information reminds me of the quote by the research author Campos who states that “Travel broadens the mind”

 

 

How to apply this in practice?

There is evidence to suggest that achieving the crawling milestone and temporary sleep disruption are tremporally linked and it’s a finding that may crop up in your practice. In children around 7-8 months old PTS we may see this phenomenon as well.

 

Being able to tell parents that, in the absecnce of red flags, illness, malnutrition, in the low risk child developmental progress may entail periods of disrupted sleep and that these disruptions are time-limited, so not to worry,  is likely to be reassuring to the parent dealing with sleep regression.

 

Again thank you for downloading the show, ill back back with you soon.