Journal Of Applied Chiropractic SciencesJanuary, 2016
The Health Implications of Proper Spinal Alignment and Support During Sleep
By Coralee A. Van Egmond, DC, FICA, CSFC, CCWP
and Ronald M. Hendrickson, MSc.
Science understands sleep to be a naturally occurring state of physical and mental respite in which we suspend our active consciousness and where most external stimuli are blocked from the senses. One popular English language dictionary defines sleep as: “…a naturally recurring state of relatively suspended sensory and motor activity, characterized by total or partial unconsciousnessand the inactivity of nearly all voluntary muscles.”[i]
It is universally agreed among researchers that sleep is an absolutely vital component of health and that sleep problems are emerging as a major threat to public health in the 21stCentury. About 70 million Americans suffer from sleep problems; among them, nearly 60 percent have a chronic disorder. Each year, sleep disorders, sleep deprivation, and sleepiness add an estimated $15.9 billion to the national United States health care bill. Additional costs to society for related health problems, lost worker productivity, and accidents have not been calculated. Sleep disorders and disturbances of sleep comprise a broad range of problems, including sleep apnea, narcolepsy, insomnia, parasomnia, jet-lag syndrome, and disturbed biological and circadian rhythms.[ii]These factors are also presenting in communities around the globe.
We remain subject to alarm and danger signals in terms of both noise and motion, but we transition into a unique state of quiet and rest for a significant period of time each day. Science has also determined that sleep is an active period of heightened anabolicstate, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. [iii]
Sleep is vital to the normal biological and psychological/emotional functions that humans must engage in to survive. Sleep enables the body and mind to rejuvenate, reenergize, and restore. Sleep allows the brain to perform vital tasks such as organizing long-term memory, integrating new information, and repairing and renewing tissue, nerve cells and other essential biochemical processes.
The health implications of inadequate sleep and an inappropriate sleep environment are serious and diverse.[iv] Regularly getting less than seven hoursof sleep increases your risk of obesity, heart disease, diabetes, high blood pressure, and other chronic illnesses.[v] Sleep deprivation affects the mind in many ways, with research observing impairmentsto short and long memory, learning, decision making, creativity, attention, reaction time and motivation.[vi]
Due to cognitive impairments, people are more likely to make errors on the job when fatigued. Research on pilots, nurses and doctors, police officers, driversand others all show increased impairments following sleep loss, and one studyestimates that insomnia results in 274,000 workplace accidents per year costing $31 billion dollars. Sleep deprivation is associated with increased depressionrisk, increased emotional reactivity, more negativityamong couples, and higher risks of mental healthissues. Children of parentswho don’t get enough sleep are more likely to miss sleep themselves, and they are also more likely to be obese. Sleep deprived kids tend to perform worse at school as well.[vii]
Falling asleep at the wheel is the most costly and devastating problem on US and European highways.[viii] Driving drowsy produces impairment on par with driving drunkafter 18 hours of wakefulness, and tired driversare conservatively linked with over 100,000 accidents, 71,000 injuries and 1,550 deaths each year. Accidents in the workplace due to sleep deprivation are commonplace and damaging to industry. Sleep deprivation is often overlooked for the role it plays in the occurrence of performance errors.[ix]These human errors caused by impaired cognitive functions after long periods without sleep have resulted in catastrophic accidents, such as the Exxon Valdez oil spill.
Ling-Ling Tsai, PhD of the National Chung-Cheng University in Taiwan, and colleagues report that the impaired error monitoring that is caused by sleep deprivation can have disastrous consequences when critical mistakes are not corrected. “Many tragic accidents involved in human errors are related not to one single error but a series of erroneous responses,” says Dr. Tsai. “One single error followed by corrections may not make it a big deal, but one single error followed by more errors leads to its own significant consequences. One night of sleep deprivation facilitates the occurrence of the latter.” [x]
The chiropractic profession has for well over a century applied a unique clinical research focus on the human spine and the many aspects of the relationship between spinal alignment and health. That focus has generated a considerable array of research that demonstrates in great detail the relationship between proper spinal support and alignment, during waking hours, in the work context and during sleep. This study is intended to identify several of the key research findings and to provide a narrative explanation of the linkage between spine support and alignment and the effect of those factors on human health, performance and also the quality of sleep.
First, it is important to examine the research record on the relationship between pressure on the human spine, and the nerves it houses and protects, and overall human health. In this area, landmark research sponsored by the International Chiropractors Association (ICA) was done at the University of Colorado in the 1980’s by C. H. Suh, PhD, SK Sharpless, a neuropsychologist PhD, and others which definitivelyshowed that even very minimal pressure on spinal nerve roots can have significant impact on neurological efficiency. In a landmark paper presented at a conference sponsored by the US National Institutes of Health, Dr. Sharpless presented a paper which included findings that showed that:
As little as 10 mm Hg. pressure, maintained for 15-20 minutes, reduces the compound action potentials of dorsal roots to about half of their initial values…It is probable that the compression block produced by even by such small pressures is due to mechanical deformation rather than ischemia.[xi]
Other research[xii]has confirmed the impact of even minimal torque-derived pressure and distortion on spinal nerves and provides an anatomical basis for the extensive repetitive motion and static position injury research that continues to explore all aspects of the relationship between compression and a wide range of symptomatology. Additional studies have been published that focus on other dimensions of the effects of nerve root compression including circulatory issues. Dr. B. M. Rydevik reported in a 1992 study[xiii] that: “Venous blood flow to spinal roots was blocked with 5-10 mm Hg of pressure. The resultant retrograde venous stasis due to venous congestion is suggested as a significant cause of nerve root compression. Impairment of nutrient flow to spinal nerves is present with similar low pressure.” Dr. M. Hause found in a 1993 study[xiv]that compressed nerve roots can exist without causing pain. Also described in the paper is a proposed mechanism of progression, where mechanical changes lead to circulatory changes, where inflammatogenic agents may result in chemical radiculitis. This may be followed by disturbed CSF flow, defective fibrinolysis and resulting cellular changes. The influence of the sympathetic system may result in synaptic sensitization of the CNS and peripheral nerves, creating a “vicious circle” resulting in radicular pain.
The research on cumulative spinal stress, from repetitive motion and load-related injury to static disuse and distress, is considerable and significant for the discussion here as it documents the relationship between spinal injury and torque or distention. Research has been extensively done that highlights the probability of spinal damage caused by sustained compressing and loading and the results leave no doubt as to the vital importance of spine support and the maintenance of minimal distortion stress on the spine.[xv] The logical next step is to explore the potential for avoiding and fostering cumulative load complications and other proper alignment and support issues during sleep.
The literature on bedding design and characteristics, spine support and the health implications of both proper and improper spine support during sleep is significant, voluminous and growing. Much of the literature had focused on the relationship between bedding characteristics, and back, neck and shoulder pain. It is significant that many if not most scientific papers on sleep surfaces start from a premise of straight line spine support as being optimal for healthy sleep. The landmark paper, A 3-D Active shape model for the evaluation of the alignment of the spine during sleeping, stated: “An optimal sleeping system for normal individuals should support the spine in its natural position…the same as that in an upright position.” [xvi] Another milestone paper stated that, “The back should be kept in a more or less neutral position, so that long lasting end-range positions of one or more tender spinal joints are avoided.” [xvii]
The influence of bed design on spine support and other elements is of central importance to the health and well-being of the individual as these elements directly correlate with the physical/psychological/physiological components of health. This includes key factors such as the mechanical properties of a mattress affecting body support and bodily postures — in short, the body, from neuromusculoskeletal standpoints, needs a sleep surface that can satisfactorily support the spinal column. Not only are the different postures undertaken during sleep interactive with and influential for the body’s structural and physiological functioning, including key elements of respiration and circulation, it involves the spine and spinal cord itself, responsible for the protection, control and coordination of the entire body.
The potential for natural sleep to have a healing effect on back pain is widely recognized.[xviii]It is further noted in references, for example as described in Back and Bed: Ergonomic Aspects of Sleeping, that “If the spinal column is unloaded during the night and if it is supported in its natural physiological shape, it should be able to recuperate from daily activities.”[xix]
There are several measurement techniques and modeling methods that are utilized to evaluate the alignment of the spine during bed rest. These include comparing the spine position on a sleep system with the spine position during upright standing. These also include diverse configurations of different bodies among individuals in the population. In multiple research studies, the influence of different types of body support on supporting the spine is studied in depth through detailed measurements that include the relation between the bed support and the anthropometrical properties (body size, surface, weight, body part configuration) of the subject.
Providing the capacity for support and the ability to move freely helps us minimize spinal deformation while essentially being unconscious during sleep. The sleep system, which is supporting the body during sleep, is clearly critical to protecting the spine and supporting the nervous system that it houses. Sleep systems can, however, force us into positions that limit body positioning during sleep. In fact, the influence of bed firmness on sleep quality has been found, such as in the study by Bader and Engdal, to show that the choice of a firm or a soft mattress is not only a matter of likes or dislikes but that individual subjects can indeed have specific needs. It is also noted in this study that an “optimal sleep surface should facilitate the naturally occurring movements by posting the least resistance, thus demanding minimal energy needs.” [xx]
The impact of custom-made bed design on back support is researched and assessed through multiple parameters, involving such physical factors as anatomy, body weight distribution, contact area diversity, and spinal alignment; behavioral and psychological components including sleep posture and relaxation; and physiological factors including components of respiratory control, thermoregulation, and the sleep-wake cycle. In short, the combined actions of these components, and their interaction, affect the physical, mental and metabolic qualify of our sleep.
Ergonomic elements of sleeping involve the combined synergy of physical, physiological, and psychological conditions which in turn affect the quality of sleep. In addition, these factors, particularly as they affect and are affected by interaction with the sleep system, in turn are critical to the sleeper’s health. The sleep system is certainly correlated with multiple issues affecting health: it is important to appreciate that while the sleep system (in particular, the mattress) may be principally recognized as the physical component of the sleep experience affecting our condition during the night, its effects are also consequently quite pertinent to our condition during the day. As described in Back and Bed: Ergonomic Aspects of Sleeping, the role of sleep systems on the spine are directly related to health and performance: “Due to an insufficiently adapted sleep system, the human body – especially the vertebral column – is often supported unsatisfactorily, resulting in low back pain or sleeping disorders.”[xxi]
A variety of evaluation methods exist for studying factors relating to mattress design that are utilized to research various elements of sleep, sleep systems, and the impact on health status along different parameters – ranging from back, neck and shoulder pain to respiration and stress measures. One basic study comparing beds and their influence on low back pain evaluated three structurally different mattresses and patients with chronic lower back pain, finding that there were differences in the influence of back symptoms, daily function (activities of daily living), and sleep, and that there seemed generally to be a correlation between lower back pain and sleep. xxii
A key study on effects of mattress firmness on para-spinal muscle electromyography[xxii]reports that subjects sleeping on soft/medium/and firm mattress systems undergoing para-spinal muscle electromyography showed an increase in para-spinal EMG readings between the soft and hard mattresses, especially in the lumbar spinal region. The findings in this full night sleep study also indicated that motor activity in sleeping subjects is significantly greater on harder mattresses. These findings pose clinical implications for patients to consider where those with muscle disorders that may find relief from bed structures that promote better relaxation, while others may benefit from bed structures that influence higher levels of muscle tension during sleep to maintain some physical stimulus while sleeping.
In addition to finding patterns of sleep system effects involving conditions such as chronic non-specific low-back pain, bedding system effects are also related to numerous changes in function and physiology such as sensation and respiration, and can be influential on sleep and sleep stages. For example, individual differences in sensitivity to the firmness of supporting surfaces (beds) were noted in the study previously referenced by Bader and Enddal (2000), and factors such as weight distribution and contact pressure, skin temperature and vapor exchange between the subject and the bedding system, as reported by Rithalia and Kenney (2000), show different physical and physiological variables are associated with comfort and ensuing quality of sleep.[xxiii] In addition, in a study conducted on bedding selection factors and the bedding effect on sleep by Tsai and Liu (2007), differences were observed with regard to sleep-related respiratory disturbances and the percentage of slow-wave sleep in relation to different bedding systems.[xxiv]
In 2010, the Committee on Posture and Technique of the International Chiropractors Association (ICA), in cooperation with King Koil Sleep Systems and the Foundation for the Advancement of Chiropractic Tenets and Science undertook the largest human subject posture study ever conducted on the issue of sleep systems and proper spine support.[xxv] The objective of this project was to study the reliability and validity of various processes to direct patients on an appropriately constructed sleep surface based upon a combination of morphometric data and subjective sleep surface preference. Three methods of measurement including pressure mapping, anthropometric measurement and still photography were conducted.Pressure images were analyzed using designated surface area analysis for each anatomical region. This regional data was exported from XSENSOR X3 PRO software into spreadsheet format. Data was analyzed using SPSS.
The results of this complex study and analysis process allowed for the evaluation of sleep system design elements that included zones of support to comply with various pressure and body-shape elements, appropriate edge reinforcement and other key components that provide for optimal spine support to allow for the optimal straight-line spine configuration during sleep in a variety of positions. This study represented a unique cooperative effort between science and industry with the objective of offering consumers of all ages and sizes sound sleep system advice based on sound assessment procedures and principles.
Research into all aspects of sleep, sleep environment and the impact on human health will continue and likely will swiftly increase as the scientific community and industry respond to the growing awareness of sleep problems as a rapidly growing and highly significant, costly, and dangerous new public health challenge. Responsible and public health oriented companies will most certainly utilize both the current data and emerging findings to design and produce better and better sleep systems for consumers of all ages, shapes and sizes. The positive results for company and consumer alike make this an important and productive endeavor.
[i]Macmillan Dictionary for StudentsMacmillan, Pan Ltd. (1981), page 936.
[iv]Osmun, Rosie, “Lessons Learned From Trends in Insufficient Sleep Across the United States,”The Huffington Post,October 27, 2015, http://www.huffingtonpost.com/rosie-osmun/lessons-learned-from-trends-in-insufficient-sleep-across-the-united-states_b_8297212.html
[v]Christopher Ryan King, BS; Kristen L. Knutson, PhD; Paul J. Rathouz, PhD; Steve Sidney, MD, MPH; Kiang Liu, PhD; Diane S. Lauderdale, PhD, Short Sleep Duration and Incident Coronary Artery Calcification, Journal of the American Medical Association (JAMA) 2008;300(24):2859-2866.
Shahrad Taheri, Ling Lin, Diane Austin, Terry Young, Emmanuel Mignot, Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index, Howard Hughes Medical Institute, Stanford University, Palo Alto, California, United States of America, 2Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin, United States of America.
[vi]DianeS.Lauderdale, Kristen L. Knutson, Lijing L. Yan, Paul J. Rathouz, Stephen B. Hulley, Steve Sidney, and Kiang Liu, Objectively Measured Sleep Characteristics among Early-Middle-Aged Adults: The CARDIA Study, Am. J. Epidemiol., 1 July 2006; 164: 5 – 16.
[vii]Van Egmond, Coralee, A., DC, FICA, CSFC, CCWP, Sleep and Your Child’s Performance in School, Journal of Applied Chiropractic Sciences, January m 2012.
[ix]“Just one night of sleep deprivation greatly hinders the ability to detect and correct errors,” Sleep,Associated Professional Sleep Societies, 06/01/2005.
[x]“Just one night of sleep deprivation greatly hinders the ability to detect and correct errors,” Sleep,Associated Professional Sleep Societies, 06/01/2005.
[xi] Sharpless SK: “Susceptibility of spinal roots to compression block.” The Research Status of Spinal Manipulative Therapy. NINCDS monograph 15, DHEW publication (National Institutes of Health 76- 998:155, 1975.
[xii]Bentley, F. H. and Schlapp, W. The Effects of Pressure on Conduction I Periphral Nerves, J. Physiol. 102, 72-82. Causey, G, The Effect of Pressure on Nerve Fibers, Journal of Anatomy, 82, 262-270. MacGregor, R., Sharpless, S. and Luttges, M. A Pressure Vessel Model for Nerve Compression, Journal of Neurological Sciences, November, 1975.Meek, M. W. and Leaper, W. E., The Effect of Pressure on Conductivity of Nerve and Muscle, American Journal of Physiology 27, 308-322.
[xiii]Rydevik BL: “The effects of compression on the physiology of nerve roots.” JMPT15(1):62, 1992.
[xiv]Hause M: “Pain and the nerve root.” Spine18(14):2053, 1993.
[xv]van Dieen JH, Toussaint HM. Evaluation of the probability of spinal damage caused by sustained cyclic compression loading. Hum Factor Bisschop A, Kingma I, Bleys RL, Paul CP, van der Veen AJ, van Royen BJ, van Dieen JH. Effects of repetitive movement on range of motion and stiffness around the neutral orientation of the human lumbar spine. J Biomechanics, 2013;46:187-91 Hoogendoorn WE, Poppel MNMv, Bongers PM, Koes BW, Bouter LM. Physical load during work and leisure time as risk factors for back pain. Scandinavian Journal of Work and Environmental Health, 1999; 25:387-403. Bisschop A, Kingma I, Bleys RL, Paul CP, van der Veen AJ, van Royen BJ, van Dieen JH. Effects of repetitive movement on range of motion and stiffness around the neutral orientation of the human lumbar spine.J Biomech 2013;46:187-91.
[xvi]Huysmans, T., Haek, B., De Wilde, T., Van Audekercke, R., Vander Sloten, J and Van der Perre, G., A 3-D Active shape model fort the evaluation of the alignment of the spine during sleeping, Gait & Posture, 24 (2006) 54-61.
[xvii]Bergholdt, Kim, DC, Fabricius, Rasmus S, DC, Bendix, Tom, MD, Better Backs by Better Beds, SPINE, Volume 33, Number 7, pp. 703-708, 2008.
[xviii]Ray Hayek*, BSc(Hons)., MChiro., Sharin Eaton**, DC., MPh., & Rod Bonello***, BSc., DC., DO., MHA, The Effects Of Mattress Firmness On Para-spinal Muscle Electromyography, Australian Spinal Research Foundation, http://www.spinalresearch.com.au/bedtest/default.html Beaumont, B., and Paice, E., Back pain, Occas. Pap. R. Col. Gen Pract., 1992, 58, 36-38. Bader, G. G., Engdal, S, The influence of bed firmness on sleep quality, Ergonomics, 31 Oct. 2000, 487-497, Jacobson, Bert H., Boolani, Ali, Dunklee, Guy, Shepardson, Angela, Acharya, Hom, Effect of prescribed sleep surfaces on back pain and sleep quality is patients diagnosed with low back and shoulder pain, Applied Ergonomics, 2010, dol:10.1016/j.apergo.2010.05.004. Huysmans, T., Haek, B., De Wilde, T., Van Audekercke, R., Vander Sloten, J and Van der Perre, G., A 3-D Active shape model fort the evaluation of the alignment of the spine during sleeping, Gait & Posture, 24 (2006) 54-61. Jacobson, Bert H., Gemmell, High A., Hayes, Brad M., Altena, Thomas S., Effectiveness of a Selected Bedding System o n Quality of Sleep, Low Back Pain, Shoulder Pain and Spine Strffness, JMPT,0161-4754/2002. Bergholdt, Kim, DC, Fabricius, Rasmus S, DC, Bendix, Tom, MD, Better Backs by Better Beds,SPINE, Volume 33, Number 7,pp. 703-708, 2008.
[xix]Haex, Bart. Back and Bed: Ergonomic Aspects of Sleeping CRC Press, Washington, DC: 2009.
[xx]Bader, Gaby G., Engdal, Sten, The influence of bed firmness on sleep quality, Applied Ergonomics, 2000 Oct; 31(5): 487-97
[xxi]Haex, Bart. Back and Bed: Ergonomic Aspects of Sleeping CRC Press, Washington, DC: 2009.
[xxii]Ray Hayek*, BSc(Hons)., MChiro., Sharin Eaton**, DC., MPh., & Rod Bonello***, BSc., DC., DO., MHA, The Effects Of Mattress Firmness On Para-spinal Muscle Electromyography, Australian Spinal Research Foundation, http://www.spinalresearch.com.au/bedtest/default.html
[xxiii]Rithalia and Kenney, 2000) Hospital bed mattresses: an overview of technical aspects. J. Med. Eng. Technol. 24, 32, 29.
[xxiv]Tsai, Ling-Ling, Liu, Hau-Min, The effects of bedding systems selected by manual muscle testing on sleep and sleep-related respiratory disturbances, Applied Ergonomics 39 (2008), 261-270.
[xxv]Betz, Joseph, DC, Hirsh, Donald, DC, Rathbun, Stephen, PhD, Van Egmond, Coralee, DC, et al, Sleep surface design, body mass index and morphology, and pressure interface distribution in perception of comfort, Journal of Applied Chiropractic Sciences, October, 2012.
The International Chiropractors Association is presently engaged in a comprehensive review of sleep research with the aim of making those findings available to chiropractic practitioners worldwide. We also believe that this review of the current state of sleep research will point to areas of where additional study is needed and, in cooperation with our affiliated educational institutions and with the support of our sleep products partner King Koil, we hope to help fill such gaps in sleep knowledge. For more information contact ICA at firstname.lastname@example.org, TEL. 01-703-528-5000.