This page is a review of Dr Doug Cary’s, Master’s & PhD research examining relationships between sleep posture and waking spinal symptoms, that is pain, stiffness and bothersomeness, plus the relationship with sleep quality. This research is world-leading in the examination and assessment that sleep posture contributes to spinal symptoms and poorer sleep quality.
If you are a clinician wanting to incorporate these findings into your clinical practice to optimise your client’s recovery potential then; jump directly to the Sleep Mastery online course.
If you are suffering from waking spinal symptoms and/or poor quality sleep, then the course is appropriate for the general public and while some terminology is ‘medical,’ the practical approach taken during the course is applicable to the general public.
Clinical Research: Sleep Posture and Waking Spinal Symptoms
We spend 1/3 of our life sleeping, so what happens at night is critical to optimising our ability to recover – both physically and mentally. As clinicians, we regularly discuss with clients their diurnal load, there has been a big gap in our understanding regarding the nocturnal load placed upon our spinal tissues. Our research conducted over the past 10 years has shown that we can’t rely on self-report of sleep posture from our clients to accurately inform us of their sleep postures, yet the postures we sleep in are critical to understanding the nocturnal biomechanical loads our spines experience. Essentially the more load, the more symptoms or spinal reactivity.
Identifying a need to research sleep posture
A key issue to date for clinicians is the lack of research examining sleep posture and waking spinal symptoms. Our group conducted a scoping review titled Identifying relationships between sleep posture and non-specific spinal symptoms in adults: A scoping review that was published in BMJ Open in 2019 and we found only four articles addressing this topic. Not much on which to base clinical decisions! One of the reasons for this was the lack of a low-cost, portable method to assess sleep posture, especially in the home environment, which is where all the action is. As clinicians advising clients, we were especially interested in the plausible biomechanical load that a client’s spine receives at night, with the key movements associated with rotation and extension.
My PhD focuses on sleep postures and their effect on waking symptoms and quality of sleep, with the goal of identifying provocative and non-provocative sleep postures and whether as clinicians we have the ability to influence them and how. You would think that we would have a good understanding of sleep posture, but given the findings of our scoping review, clearly, this was unexplored territory. We needed to classify sleep postures, find imaging equipment, develop and test a sleep posture recording protocol in the home environment, determine if people waking in pain slept differently and create and test the effectiveness of a simple education intervention to change sleep posture habits.
The first part of this process was a pilot study to gain some understanding of this relationship and how we could measure sleep posture in our clients’ normal sleep environment.
Developing Methods to Measure Sleep Posture
Our 2016 pilot study titled, Examining the Relationship between Sleep Posture and Morning Spinal Symptoms in the Habitual Environment Using Infrared Cameras was a sample of convenience (i.e. whoever we could convince to have cameras set up in their bedroom!). It showed that people are not able to self-report their sleep posture accurately (hence the need to video them) and while not statistically significant, it was noted that participants who spent greater periods of time in supportive side lying, had fewer mornings with symptoms per month than those that slept in provocative side lying. This gave us a plausible reason to continue to pursue this idea of biomechanical load influencing waking spinal symptoms.
We determined our recording protocol was robust and effective with good footage obtained under sometimes ‘challenging’ environments with children, pets and camera failure being some of the issues. Other technical issues with equipment and sleep posture classifications were ironed out.
Sleep posture is classically described as supine, prone and everything else is side lying. Under this classification, we spend approximately 60-70% of our sleep time side lying. A problem with this classification structure is that it doesn’t account for the wide variety of side-lying sleep postures, some being potentially provocative on spinal load, while others are not. For this reason, we wanted to sub-classify the broad side lying category based upon spinal loading into two subcategories, provocative and supportive side lying. With the footage obtained, we are able to accurately identify the cardinal sleep postures and the new sub-classified provocative and supportive side-lying postures.
Confirming Accuracy of Sleep Posture Measurement Tools
Determining the validity and reliability of equipment that assesses sleep posture in the home environment had not been done before, especially when focusing on the possible biomechanical effects of spinal rotation and extension inside lying. We created a ten-minute video of sleep postures under different conditions of bed coverings (none, sheet, sheet + duvet) to simulate a realistic home situation, and different lighting (natural light and infrared light). Unique to our protocol was the use of two cameras in two different viewing planes. This video was viewed by 20 health professionals and each sleep posture was scored. We found both the intra- and inter-rater reliability were excellent. Meaning, that clinicians can use this protocol to accurately assess sleep posture in the home environment.
This paper is titled Examining the reliability and validity of a portable sleep posture assessment protocol, using infrared cameras, under a variety of light and bed cover situations in the home environment and published in WORK: A Journal of Prevention, Assessment & Rehabilitation.
Comparing Sleep Posture in Symptomatic/Non-Symptomatic Sleepers
The fourth paper in our series of sleep studies compared symptomatic (neck or lumbar) and our control group across a broad range of pain, sleep and quality of life measures. The aims of this research were to compare sleep posture and sleep quality in participants with and without waking spinal symptoms. This is the first study using a validated objective measure of sleep posture to compare symptomatic and Control group participants sleeping in their home environment. In general, we found that participants with waking spinal symptoms spent more time in provocative sleep postures, and experienced poorer sleep quality. This paper is titled Examining relationships between sleep posture, waking spinal symptoms and quality of sleep: A cross-sectional study, published in PLOS One.
While we suspected that people sleeping in certain postures could be provocative of waking spinal symptoms, we were surprised to find that this also reflected through to their sleep quality. When sleep quality is negatively affected, this has flow-on effects to a much broader range of health outcomes like; memory & learning, fertility, maintaining a healthy body weight, cardiovascular health (high blood pressure, heart attack, stroke) and workplace injuries. So in addition to preventing waking spinal pain, improving sleep posture could also be an important aspect in a range of other health domains.
Ongoing Research
Over the course of my PhD. in collaboration with colleagues, we developed a reliable and valid method to measure sleep posture. A scoping review confirmed a lack of research in this particular area of pain science. Following the development of methods to measure sleep posture, we identified certain sleep postures that seem related to increased waking spinal symptoms, like pain and poorer quality of sleep.
In our most recent study, we used a sleep educational package in a longitudinal study of symptomatic participants (neck and lower back pain), to determine ;
- If participants are able to change their sleep posture when asleep and if they can,
- What changes are noted in their regular waking spinal symptoms and
- Validated baseline quality of life, quality of sleep and spinal disability questionnaires.
Data has been collected and analysed and will be written for manuscript submission or conference presentation in the near future so that we can spread this important clinical information.