We asked Physiotherapist Catherine Jones from the Clinikind Practice in South Wales (www.clinikind.com) to give us the science behind neck pain, sleep posture and selecting the correct pillow. She put this together from the most up to date scientific research: -
In a twelve-month period, 37% of the UK’s population will experience neck pain (Rizello 2019), a condition ranked globally as the fourth cause of chronic disability (GBDS 2015). As well as the personal cost in terms of quality of life, this problem places an enormous burden on the economy and healthcare systems of developed countries, as technological advancements establish increasingly sedentary occupations and pursuits that highly correlate with neck pain (Gerr and Fethke 2011; Buckley et al. 2015).
Non-specific neck pain is defined as neck or shoulder girdle pain with or without referral to the arms. In most cases, although it is considered multifactorial in origin, with no specific cause found, poor posture is a risk factor (NICE 2018). Taking the contemporary view of osteoarthritis as the failure of multiple tissues, although facet joint articular cartilage cannot directly cause pain, its degeneration affects surrounding tissues through altered biomechanics and postures, meaning that it could be the initial trigger for the degenerative cascade, along with the intervertebral discs and muscular loading. Although osteoarthritis is considered an inevitable health problem (Diao et al. 2018), strong evidence exists to suggest that pathologic loading patterns can accelerate degeneration (Jaumard et al. 2011; Anderst 2015; Kim et al. 2015). Such pathological mechanical loading could activate nociceptors, leading to neck pain and the potential for central sensitization and the development of chronic pain (Gellhorn et al. 2013; Kim et al. 2015).
Cohort studies have also found evidence to support a reciprocal relationship between sleep problems and chronic pain (Finan et al. 2013). The frequency of self-reported sleep problems increases with age, whereas 40% of individuals who consult a GP will complain of sleep problems, this rises to 63% for individuals aged 60 years and over (Almeida and Pfaff 2005; Desaulniers 2018). As life expectancies rise in the vast majority of industrialized countries, sleep problems and neck pain will become a growing concern. Therefore, given that high-quality sleep is essential to well-being, that humans spend a third of their life in sleeping positions and that the ever more vulnerable cervical region is potentially effected by postural concerns, a window of opportunity to prevent degeneration may exist. This could indicate that it is increasingly more important to consider sleep posture in the management of neck pain.
Sleep posture as an opportunity to contribute to reduced pain?
Static postures such as sleeping positions display forces that are in biomechanical equilibrium and so the static sleeping positions we adopt may be mistakenly dismissed as innocuous. However, this does not indicate an absence of tissue loading. Nachemson and Elfstron (1970) state that the primary function of the lying down position is to support the weight of the body, allowing the muscles and intervertebral disks to recover from the almost continuous load sustained throughout the day. For that to occur, sleep postures require symmetrical muscle activity between the two sides and minimal electrical activity to restore the musculoskeletal system (Sacco et al. 2015). It has been demonstrated that a pillow height that brings the alignment of the spine into lateral flexion in either direction in side-lying increases the electrical activity in the neck and mid-upper back. Whereas, a 10cm pillow height emitted the lowest EMG activity in the middle trapezius and resulted in the best perception of comfort. With muscle activity similar in the lower and upper sides of the side-lying upper body, better alignment and reduced loading was potentially indicated (Sacco et al. 2015). Therefore, the difference between the forces supporting the head and those supporting the neck reflects the capability to maintain spine alignment. As such, this has been included in pillow design as a key factor (Huysmans et al., 2006; Verhaert et al., 2011) as poor pillow design is known to provide inadequate support of the cervical spine, resulting in discomfort and pain (Liu, Lee & Liang, 2011; Wang et al., 2014).
However, people often choose a pillow based on their immediate perception of comfort, usually opting for softer pillows, which could lead to selecting an inappropriate pillow that induces or worsens neck pain (Hurwitz et al., 2009; Leilnahari et al. 2011; Liu et al. 2011). However, although a firm surface would theoretically offer more postural support (Bridges et al. 2003), helping to stabilize the spine and reduce undesirable spinal distortion over time (Sacco et al., 2015; Verhaert et al., 2011), a firm surface is likely to be poorly tolerated, as reduced skin perfusion leads to reduced comfort (Bridges et al. 2003). Therefore, a properly designed pillow should allow greater surface contact with the head and neck, for a more even distribution of pressure (Chen and Cai 2012) with a retained perception of softness and the mechanical ability to maintain its supportive properties.
Unfortunately, selecting the correct pillow height can be difficult, as the optimal pillow height does not always correlate with individual anthropometrical dimensions, such as length or width of the head-neck complex (Erfanian et al. 2004; Wang et al., 2014), with issues such as cervical muscle strength having an input into optimum pillow height for comfort (Wang et al. 2014). Never the less, pillow comfort affects sleep quality and a simple change of pillow can effectively improve sleep (Persson 2006; Gordon and Grimmer-Somers 2010), with almost half of the participants in the study of Desaulniers et al. (2018) reporting that their pillow was not comfortable and effected their sleep. Therefore, a credible hypothesis may be that simple, relatively affordable; minor changes could promote sleep, benefitting both physical and psychological health.
So, what would justify keeping an uncomfortable pillow? It is possible that the vast choice of materials, sizes and shapes available combined with a lack of guidelines for consumers would affect some peoples decision to take action. This is perhaps an opportunity for physiotherapists to make a difference to this population? But how is this achieved based on the limited evidence available?
With the variety of materials reporting differences in comfort (Gordon and Grimmer-Somers 2010) and as anatomical body measurements are not necessarily good predictors of optimal pillow height, the solution may be as suggested in the study of Persson (2009), that concluded that the optimum pillow should be one that is specially selected and individually tested, that is soft, with good shape, comfort and support to the neck. At this stage, although we understand that loading may be exacerbated in certain pillow designs in terms of their supportiveness, our best advice may still be dependent on the opportunity to try the pillow, especially as most patients will make mistakes in this area that they will stick with and miss the chance to reduce pain and improve quality of sleep (Persson 2009; Gordon and Grimmer-Somers 2010).
Catherine's advice? Choose a pillow, like the Gx Suspension Pillow, that comes with a 30-day comfort guarantee, but give the pillow long enough to get used to it. If you have been sleeping in the wrong position it might take a while to get used to sleeping in the correct position.
References
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