Shallow Water Blackout
Learn more about the dangers of Shallow Water Blackout
The term ‘Shallow Water Blackout’ is commonly used to describe a loss of consciousness under water caused by a lack of oxygen to the brain following breath-holding. Although the term refers to ‘shallow water’, it can occur at any depth. It occurs because the normal, protective “breakpoint” – the irresistible urge to breath - has not been reached before consciousness is lost.
The most common cause is voluntary hyperventilation before submerging. Hyperventilation, or overbreathing, involves breathing faster and/or deeper than the body requires. There are other less common causes, relating to heart abnormalities, which lead to loss of consciousness in the water following hyperventilation.
Royal Life Saving urges people to never hyperventilate before enjoying underwater aquatic activities.
Royal Life Saving supports the campaign by the Divers Alert Network (DAN) to raise awareness of the risk of breath-hold blackout in breath-hold diving and surface snorkelling. The breath-holding blackout campaign was created to reinforce the message that breath-holding blackout remains responsible for on-going deaths in both the experienced and inexperienced and needs to be taken seriously.