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How Sleep Surfaces Affect Our Backs

by Bill Ancell(more info)

listed in sleep and insomnia, originally published in issue 48 - January 2000

There are approximately three million beds and mattresses sold annually in the UK. 30% of beds and mattresses purchased are for relief from a back problem, and 35% of purchases result in a disappointment for at least one partner or both.

Traditionally, beds have been viewed as furniture, and marketed in an extremely visual way by retailers. Terms such as orthopaedic have been introduced by the bed manufacturers, which, in fact, has very little meaning as to the performance of the mattress incorporated in the bed, other than to suggest some form of medical benefit. To date, there has been little or no medical research on sleep surfaces in the form of randomised controlled clinical trials anywhere in the world.

image of spine in prone position

Mattresses should provide an environment in which the skeletal system is fully supported, whilst maintaining correct postural alignment. Equally, this needs to be achieved with comfort i.e. without exerting undue pressure on the soft surface tissue, bony prominences, or muscles of the sleeper. Shear forces also play a part in causing discomfort, particularly amongst the elderly. This is a stretching of the surface and deep tissue, often the cause of pressure sores in hospitals and nursing homes, one of the few areas that has been widely researched.

In 1997, MAS (Medical Agency Services) carried out a survey of 2500 physiotherapy patients, that showed that 98% of bed purchases were made without any input from a healthcare professional, although they were seeking relief from a medically related condition. Equally, back specialists are reticent to recommend any mattress, as they themselves find it difficult to purchase the correct mattress!

Interestingly, the survey also showed that lighter weight females sought more back and neck treatment where the partner was on average 50 lbs. heavier, and using a firm mattress that they were particularly happy with. The expression 'princess and the pea' is often used by lighter weight females, when questioned about firm mattresses.

Approximately, 28% of all patient visits to GPs involve some form of back or neck related pain; therefore, it is somewhat concerning when many GPs continue to recommend a hard mattress for back pain sufferers, although there is no medical evidence available to support this advice.

Hard mattresses are good for you! This phrase has been over-used, and been the cause of much disappointment for consumers. Hard or very firm beds certainly do support the skeletal system, but take little account of pressure affecting conditions, i.e. arthritis, rheumatoid arthritis, insomnia, bursitis, spondilosis, etc. Equally, this type of mattress can often elevate the pelvis, especially females with wider hips, causing lateral distortion of the lumbar spine and shoulder compression. Back sleepers will force the hips forwards into an unnatural position, and flatten the thoracic spine, potentially causing facet joints to lock, and irritation of sensitive joints.

Post-operative patients, particularly replacement hip recipients, having to lie supine for extensive periods to assist tissue healing, often find themselves suffering from different low back symptoms after this experience on a hard or too firm bed.

For side position sleepers, stress can be increased on the elevated hip, where the limb is brought across the pelvis. This stress would be substantially reduced if the hip in contact with the mattress was accommodated correctly, thus reducing the distance between the elevated hip and mattress surface. Many physiotherapists and other back specialists recommend the use of a pillow placed under the elevated limb, or between the knees, in order to open the gait during sleep.

Equally, height, weight, and weight distribution are key factors to take into consideration when attempting to provide low pressure, low shear, and skeletal support. Wide shouldered individuals, with smaller hips and limbs will generally experience shoulder compression on a hard mattress, although the low back is supported correctly. Narrow shouldered females particularly, with larger hips will not have sufficient upper body weight to depress the shoulder area of a hard mattress, resulting in lateral stress of the spine in the side sleeping position. These individuals will almost always have low back pain or stiffness on waking at some time, in addition to experiencing difficulties in finding the correct pillow.

Pocket sprung mattresses incorporate more springs into the mattress core in an attempt to cushion and redistribute the weight of the sleeper. The springs are normally covered with a type of fibre in order to further cushion the effect of the springs. This is an elastic surface that basically exerts a counter-pressure equal to the downwards force of the sleeper. In order to achieve a more contoured feel, and redistribute weight, many manufacturers incorporate a substantial number (hundreds) of springs.

Water Beds are excellent at redistributing pressure as the weight applied is floated across the surface, which has the effect of placing more of the mattress in contact with the body. Unfortunately, weight distribution varies enormously, and as the mattress works on displacement to accommodate the sleeper, postural alignment is difficult to achieve when the larger weight (hips) forces the water to the shoulder area resulting in shoulder compression and a curved spine to side sleepers. Some water beds are compartmentalised, but the chances of getting exactly the right balance of water for both sleepers on a double bed is difficult to say the least! This problem can sometimes be resolved by altering the amount of water.

Latex is widely used in mattresses, and provides for an elastic surface that is already a cushioning surface in itself. Latex is marketed as a natural product, although 80% of the world's latex is now synthetically produced! The latex foam normally contains ventilation holes from the top to bottom surface of the core; this is also used as a way of softening certain areas of the foam core to accommodate shoulders, etc. A mattress ticking is then used to cover the mattress, and further cushioning fibre is often added. The cover is an important component of the mattress, and if it is unable to stretch, then hammocking occurs and pressure is increased on the soft tissue of the sleeper.

Quality mattresses can be very expensive. They may be made with top quality materials but if they do not provide muscular and skeletal support for that individual, then the product is incorrect and unsuitable, irrespective of the cost.

Mechanical pain affects most people at some stage in their lives and postural changes are common. Rotation of the pelvis can cause one leg to appear short, one shoulder to drop, and the head to tilt. Because of the shorter limb, weight is transferred to this leg, often resulting in sciatic pain in one of the limbs. This condition can be extremely debilitating, and a problem for back pain specialists to stabilise if the patient sleeps on an incorrect mattress. 95% of back pain problems are mechanical and can be treated successfully by chiropractors, osteopaths, and physiotherapists.

As we grow older, muscles, ligaments, and tendons shorten, generally resulting in a stiffening of the spine and associated joints. This often leads to postural changes and mechanical pain, as the skeletal system is faced with an imbalance, causing muscles to be used out of equilibrium. One hip can be loaded when walking, causing inflammation of the joint as the hip is constantly used in the wrong alignment. Facet joints of the spine can lock causing a further stiffening of the spine, resulting in back or neck pain.

Mattresses can either assist treatment of mechanical pain, or seriously hinder recovery. If the specialist is able to mobilise the affected joints, there is no point in placing stress on the affected area for eight hours during sleep, as the brain will simply trigger a guarding action, by activating muscles and ligaments to compensate for the lack of support. With deep sleepers who lie in one position for long periods, this can have the effect of allowing the muscles to get into painful spasm. Light sleepers may toss and turn all night to overcome the problem of spasm, but of course they are not getting quality sleep.

Quality sleep is an elusive commodity for millions. The complex process of attaining a quality sleep pattern can be compromised by the wrong mattress. Of course, there are many factors that can affect sleep, not least the taking of alcohol at night to aid the sleep process. Unfortunately, this is only a short term solution, as alcohol affects the natural melatonin produced, which is the hormone governing the sleep pattern. The sleeper will often wake after a few hours, and be unable to get back to sleep. Stress is an important factor when trying to physically get to sleep in the first place. Muscles will be tense, blood flow decreased, the brain will be overactive. Therefore, a comfortable, cosy, yet supportive environment, with low pressure and low shear is required in order to: allow for muscular recovery, remove pressure from bony prominences (shoulders, hips, knees, and ankles) and enable the musculo-skeletal system to relax.

The reduction of pressure will normally enable those with difficulty in staying asleep, to sleep for longer periods.

Profound sleep can have side effects if the individual has postural problems. Lying in the same position for long periods, where some form of pelvic dysfunction is identified, will certainly result in substantial muscle spasm in the lumbar area on waking.

Restlessness during sleep can be extremely frustrating for many individuals, as there is often an uncontrollable urge to continually reposition themselves before, and during sleep. Restless legs is a relatively common condition, normally exacerbated by pressure to the hips when sleeping in the side position. It is much misunderstood, but increasingly suggested by specialists that excessive pressure to the soft tissue and muscle surrounding the hips causes these muscles to become traumatised with reduced circulation, resulting in stimulation of the limbs.

Sleep should be a fully remedial and refreshing experience. The average number of movements in sleep is approximately 50-80, although this can be reduced to 18-20 on the correct sleep surface. The human body has approximately 700 muscles, most of which need to relax during sleep! Certain muscles, such as calf muscles act as blood pumps and assist circulation during sleep, but most muscles associated with the spine should relax when sleeping.

Insomnia, a total lack of sleep, can be attributed in many cases to a poor or unsuitable mattress, or even something as simple as an incorrect pillow. Many insomniacs are simply over-sensitive to poor skeletal support, shoulder compression, or dysfunction of the cervical spine (neck). Stress related insomnia can be relieved when the muscular system is afforded the chance to recover during sleep, which will normally give longer periods of sleep to these sufferers.

Visco-elastic mattresses comprised of heat and weight sensitive polymers, have been shown to be of great help in reducing pressure whilst maintaining skeletal support. Used widely in hospitals and nursing homes, these mattresses conform exactly to each individual's shape, and weight distribution, and immediately reform to the new shape when turning in bed. Generally, this type of mattress is only available through a specialist source and is not normally found in retail stores. One advantage of this type of material is that two sleepers of vastly different weights can be correctly accommodated on the same mattress, avoiding the need to resort to twin beds after years of companionship during sleep.

Pillows made from visco-elastic material support the skull and neck without applying undue pressure, as they conform to the exact shape of the sleeper, thus spreading the weight evenly and uniformly along the vertebrae.

Pillows are a constant cause of frustration for many. It has been shown that probably 80% of pillow problems are not related to pillows at all. The problem is normally mattress related, where the sleeper is unable to get the shoulder into the correct position, and feels the need to elevate the skull. In addition, on the wrong mattress, the skull is at a different height when sleeping on the back or side. This can have the result of forcing the head forward when turning involuntarily onto the back, resulting in neck pain, and stiffness between the shoulder blades on waking.

The shoulder should not be placed at 90 degrees to the mattress as this may trigger spasm in the trapezius muscle. The trapezius muscles perform a variety of actions, including acting as a platform for elevating the skull and need to recover during sleep. If the shoulder is placed slightly forward on the mattress, in front of the sleeper, assuming the mattress can accommodate this position, the risk of forcing the scapula towards the spine is reduced. When positioned in the 90 degree position sleepers may wake with upper arm pain and sensation to the little and ring fingers.

If a pillow applies excessive pressure to the neck in the back sleeping position, particularly the C2, C3, vertebrae, then treatment that has been provided will almost always be compromised. Pressure can irritate the nerve sheaths, sensitive muscles, and facet joints in the neck. Equally, if the joints are not resting easy, the inflammatory process may be sustained and any recovery will be much more difficult.

Shoulder compression on a firm surface will often force the scapula (shoulder blade) towards the junction of the upper spine and neck, and affect the C6/C7 vertebrae. The nerve pathway at this site travels down the arm, and causes either upper arm pain or pins and needles in the little and ring fingers or both, especially if there is already a problem in this area.

Many shoulder problems are caused by referred pain from the neck, therefore, stabilising the neck during sleep is of paramount importance. The skull is, in the main, held up by the shoulder muscles, therefore any compromising of these muscles during sleep will generally not be solved by a pillow, if the shoulders are being compressed for long periods.

How do you buy a bed? A question asked by so many. Surely, if the muscles and ligaments take on average, 5-7 nights to adjust to a new mattress, how can lying in a bedding showroom for ten minutes or so, be the safe route to a successful purchase?

You cannot test a bed when you are awake! Even our night attire will have an effect on the comfort level of a mattress. Tight, daytime clothing can often give a false perception of a bed, as the fabrics do not give on the mattress. Loose clothing should be the order of the day when trying a mattress in a showroom.

Involuntary movements made during sleep, are not normally tested when we are awake in a retail store. Most purchasers in showrooms test their prospective purchase lying on their back, although they sleep on their side for the most part.

Many European retailers allow purchasers to try a bed or mattress for at least a week. Therefore, in order to rest easier, you may have to insist that the retailer allow you to trial the bed or mattress at home!

Advice from Wendy Emberson MCSP SRP, Chartered Physiotherapist:

 

1 If you sleep well on your current mattress and get up feeling lithe and ready for the day – do nothing.

2 If your mattress is too firm, i.e. your shoulders and hips don't sink into the bed, and you feel as though you're balanced on top of the bed rather than supported by it – then
consider the possibility of buying an overlay of the new visco-elastic polymer material.

3 If your mattress sags in the middle – then consider buying a new supportive mattress that allows for your shape and weight. You may prefer a conventionally sprung mattress – not too firm and probably with standard posture springing. You may like to try the visco-elastic material as a full thickness mattress.

4 Pain in the neck and shoulders? Sleep with one pillow. Again there are now pillows in this same material. But also look carefully at your mattress – if your shoulders don't sink into the bed then you may be pushing your shoulders into your neck and causing the pain.

5 Don't forget to check your children's beds as well. They can suffer disturbed nights just like adults. [With the increase in back pain in children, their beds are equally important.]

6 If you are not sure whether your mattress is a problem, then ask someone who has the required knowledge – not just an opinion!

7 Ask the supplier if you can return the mattress within a specified time, if it does not improve your night's sleep. You cannot tell by lying on a showroom bed for a few
minutes. After all, if you are allowed to test drive a car, then why not a bed?

Buying a new bed can be an expensive mistake. It is not just the cost of the bed, but the loss of work, the loss of income to both employer and employee, and the enormous personal cost in terms of pain and possible disability that can be reduced and maybe even avoided. Most people will keep a bed for about 10 years. Make sure you don't buy 10 years of
avoidable pain!

Reference

• With sincere thanks to Jonathan Betser DO Woodside Osteopathy Clinic, Dunstable, Bedfordshire for his kind contribution to this article.

Comments:

  1. Dr Karen Evangelista said..

    Excellent information and advice. I am terrible for trying to skirt over loads of written information and trying to deduce an answer ~ I actually read all of this and it was extremely helpful. Thanks.


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About Bill Ancell

Bill Ancell is the Managing Director of Medical Agency Services (MAS) Ltd. In recent years he has concentrated on designing marketing strategies for healthcare products to both the medical sector and consumers. In 1993, Bill was introduced to visco-elastic materials and became fascinated by the implications of sleep surfaces and the lack of credible medical evidence on mattresses and beds in general. In 1994 MAS started work with osteopaths, physiotherapists, and chiropractors, in order to gain more knowledge about mechanical pain and the effect of mattresses on treatment provided. MAS currently deals with over 4000 clinics throughout the UK.

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