IDEAL SLEEPING POSTURES
In the ideal sleeping posture, the following points are critical to good ERGONOMICS:
Supporting the Spine One of the major factors adversely affecting the quality of sleep is the unsatisfactory support of the spine during sleep. A good sleeping system and the correct sleeping posture allow back muscles to relax and promote the rehydration of the unloaded intervertebral discs of the spine.
Local Ischemy Ischemy arises in your body zones that are in contact with your sleeping system. It results in the formation of toxic metabolic substances that stimulate sensitive nerves, which in turn, cause you to change your posture before it gets too painful. An extreme example of the effects of local ischemy is the development of "bedsores" in bedridden persons who remain in a particular position for protracted periods of time. This undesirable reaction to your sleeping system emphasizes that a good sleeping system provides firm support but it should not be too hard to cause local ischemy to develop disturbing your sleep and making you change your position many times during the night.
Evaluating your Sleeping System Since most of your body weight is concentrated around your hip area, mattress wear is greatest at this point. If your mattress already has a depression in this area, sleeping on your back can cause increased anterior intervertebral disc pressure, or if you sleep on your side, increased torsion of the low back. Some sleeping systems have a stiffer zone corresponding to the hip area while some visco-elastic systems intrinsically disperse the concentrated body weight into the mattress material. You must also consider the type of pillow that you are using. Pillows should support your neck in its neutral and lordotic posture.
Enough Sleep? Sleeping habits are age-related. Older people sleep for a shorter time, change their positions less frequently, and have a preferred posture to sleep in, mostly on the right side and rarely in a prone position. Some research suggests that all one needs is 4 cycles of Rapid Eye Movement (REM) sleep per night to "re-organize" our brain patterns. As each REM cycle lasts about 45 minutes, some people can survive on 4 hours of sleep. But generally, 6 to 8 hours of sleep per night provide adequate mental and physical rest.
Postures - which is the best for supporting the spine? Most people have a preferred posture to fall asleep in - statistically, 65% sleep on their side, 30% on their back, and 5% on their front. Generally, sleeping on one's back provides the best support as this position spreads the weight of your body over a larger surface area. Sleeping on one's side is adequate when there is good head and neck support; that is, the neck should assume a neutral posture.
Incorrect Posture - Sleeping on your front increases curvature of the lumbar spine resulting in pressure on the posterior joints and tension on the anterior soft tissues. Furthermore, in this posture, more of your body weight rests on your rib cage and intestines, which in turn press against the diaphragm and onto the lungs. This posture also necessitates turning the head to the side for improved breathing, which increases neck rotation.
Source: Hong Kong Chiropractors' Association