The "blackout challenge" is a dangerous social media trend that has gained popularity in the last two years.
The deadly online game encourages people to restrict their breath until they fall unconscious. This can cause low levels of oxygen in the brain that can lead to seizures, serious injury or death.
It has existed for more than a decade under different names - including the "choking game" and the "pass-out challenge" - and has since popped up on TikTok.
