北象鼻海豹每年約有 9 個月在海洋中生活，平均每天只睡 2 小時。 最近的一項研究發現，牠們在深潛過程中睡眠 10 分鐘，而且身體會繼續螺旋下降到水深377米，牠們的大腦會在氧氣耗盡之前喚醒牠們。在深水中睡覺可以避開通常在水面捕食的虎鯨及鯊魚。當北象鼻海豹回到陸地上時，每天會睡大約 10 個小時。
Northern elephant seals spend around 9 months in ocean each year, and sleep for only 2 hours each day in average. A recent study found they spiral down for about 10 mins during deep dives of up to 377meters below surface, and their brains will wake them up before running out of oxygen. Sleeping in deep water can avoid orcas and sharks’ attack where they usually hunt at the surface. On the other hand, when they are on land, they will sleep about 10 hours per day.