“Sleep is the golden chain that ties health and our bodies together”
Thomas Dekker – English dramatist (1572 – 1632)
As a physiotherapist and ergonomist I usually ask my clients about their sleep behaviour and habits. How long do they sleep, how do they rate the quality of their sleep, what position do they sleep in and do they wake with pain at all either during the night or in the morning?
The reason that I am interested in this is because the positions and postures that we adopt during our sleep can have a profound affect on the quality and length of sleep we get. Why is this important when I have an athlete with a shoulder impingement that just wants to play tennis again? Or a runner with hip pain?
The simple answer is that sleeping posture is just as important as those we adopt whilst awake, in helping to diagnose, assess and treat injury and pain. Many athletes fail to realise that the position that they sleep in can aggravate an existing injury, slow down the healing or even contribute to the development of symptoms. Just because you have slept in a certain position for years and it feels comfortable does not mean that it is not causing you a problem!
Sleeping a neutral position is the ideal. This really just means a position in which your muscles and joints can rest naturally in mid range, without any real excess pressure or force being applied.
Sleeping prone (on your front) is not a good position. This is because to be able to breathe we turn our head to the side, placing the neck in a full rotated position, we call this an end range position because the joints cannot turn anymore and are at the end of their movement range (as when you look over your shoulder). This increases the torsion through the small joints and discs in the neck which over time can contribute to strains of the soft tissues and damage to the joints. Additionally if you use a pillow in this position, your neck is also forced in to a degree of extension which further in creases the forces to the spine. Whilst this is happening the low back is also in a position of relative extension and the joints and discs are exposed to unwanted forces too – similar to leaning slightly backwards for a few hours! Furthermore, if we consider arm position and a person sleeps with one arm up near to the head, the shoulder joint is also put into an end range rather than neutral position and just like the neck and the low back, pressure is exerted on to the joints and soft tissues.
Increased pressure or force through an area can disrupt blood flow, slowing healing or causing feelings of pins and needles. If joints are put in to an end range position the ligaments and muscles on one side can become stretched and overtime they fail to return to their ideal resting position. This means that they can no longer support and protect the underlying structures as well as they should. Mean while the soft tissues on the opposite side of the joint become tight and shortened leading to increased forces through the joints even when you are awake and moving around.
The end result is an imbalance around the joint that can contribute to altered limb kinematics (movements and control), which ultimately has an impact on skill and performance. As you can appreciate this not an attribute any athlete aspires to achieve!
In addition to the physical effects of sleeping position on your body, the effect of poor or broken sleep due to pain can have other unwanted effects. It has been demonstrated that a lack of sleep can interfere with the learning and automation of new skills. Most athletes focus on the importance of repeating a new skill over and over agin so that it becomes automatic and can be called upon unconsciously. However the role of sleep on learning is poorly understood. When an activity is performed the brain continues to learn even after the activity is no longer being performed, this further improvement has been shown to occur only during sleep, not during the equivalent time of wakefulness. (Walker and Stickergold. 2006).
Walker and Stickergold (2006) carried out a series of tests and successfully demonstrated that sleep deprivation following the performance of a task resulted in a lack of learning improvement, even after a night of recovery sleep. It is therefore vital to sleep the night of learning a new task so that neural plasticity occurs in the brain and subsequent motor improvements are gained.
It is therefore important if you do have pain, to find a comfortable sleeping position that allows you to sleep well.
Most people are aware that we need sleep to recover and repair. During sleep the body’s metabolic requirements are reduced and it releases growth hormone which is important for growth and repair. Although growth and repair is an ongoing physiological processes, it is whilst we sleep that approximately 95% of the hormones connected with this are released. The most powerful, natural ways to stimulate the body to release growth hormone are exercise and sleep. If an athlete exercises during the day , the levels of circulating growth hormone will increase during the following night, but if an athlete does not sleep or has broken sleep due to pain these levels can fall significantly (This is linked specifically to the disruption of slow wave sleep).
This can result in a change to immunity due to a depletion of circulating white blood cells, which we need to fight infections, and the altered levels of melatonin and growth hormone which are necessary for growth and repair. Even small amounts of poor sleep have been demonstrated as having a significant impact ( Irwin et al. 1996) and overtime this could lead to impaired immunity.
The best positions to sleep in are on your back or on your side. Sleeping on your back will allow your body to naturally fall into a neutral position. Try and use one pillow so that your head is not pushed up into a flexed position or if you sleep on your side one or two pillows should be used to fill the gap between your head and shoulder.
There are many ways to modify sleeping positions if your have a specific injury and talking to your physiotherapist will help you find a comfortable position that will help you. For example, some hip injuries such as impingements may respond better to sleeping on your back or sleeping on the uninjured side with enough pillows between your knees to enable the injured leg to remain in a neutral position, preventing the soft tissue from being squashed during the night.
Walker M. P, and and Stickgold R. (2006) Sleep, Memory and Plasticity. Annual Review ODF Psychology: 57: 139-66
M Irwin, J McClintick, C Costlow, M Fortner, J White, J C Gillin (1996) Partial night sleep deprivation reduces natural killer and cellular immune responses in humans. 10: 643-53