Disc bulges/prolapsed/slipped are very common back complaints/injuries, but its no wonder with the amount of work they are put through.
From the second cervical vertebrae right down to the sacrum, the bodies of adjacent vertebrae are separated by these discs.
Each disc has a tough outer fibrous ring and an inner, soft, very elastic core. The discs cushion the vertebrae and permit movements of your spine while absorbing vertical shock.
The inner jelly like core of the disc can absorb fluid and swell. However this is normally counteracted by the weight of the body pressing the discs between the vertebrae.
At night while you are asleep the swelling process is not put under any pressure so the discs can then expand back to normal again. This explains why we are somewhat taller when we get up in the morning than we are towards the end of the day.
The slipped disc is in fact a disc from which the jelly like content has bulged or escaped their normal boundaries (herniated or prolapsed) causing the disc to impinge on your ligaments and nerves. And, although herniated discs do not always cause problems, they can produce some painful symptoms.
Looking after your discs is therefore very important and some contributing factors to slipped/prolapsed/herniated discs are often the result of bad posture and poor body mechanics during daily activities. Things like bending and lifting incorrectly can cause them as can an injury due to sports. As we age, the discs gradually lose water and become less springy so keeping fit and carrying less excess weight, is another important factor.