Final answer:
Decompression sickness (DCS), also known as 'the bends', is a potentially serious condition caused by ascending too quickly during a dive, which can lead to gas bubbles forming in the bloodstream.
Step-by-step explanation:
The numbing aesthetic effect experienced while diving is commonly referred to as decompression sickness (DCS), or "the bends". This condition arises when a diver ascends too rapidly to the surface, causing ambient pressure to decrease and the gases dissolved in their blood to become less soluble. The rapid pressure change can result in the formation of gas bubbles in the bloodstream, leading to various symptoms which can include rashes, joint pain, and even paralysis or death if severe. To prevent DCS, divers are advised to ascend slowly, at about 10 or 20 m/min, and take decompression stops as needed. However, if preventative measures fail, hyperbaric oxygen therapy in a decompression chamber may be necessary as treatment.