Yet humans are rarely attacked by a shark, while millions of sharks are killed by humans. Some populations of shark species, such as the shortspine spurdog, may have dropped by 95 percent. The sharksâ population decline has a ripple effect â throwing entire marine ecosystems out of balance.
Quick Answer. A normal blood oxygen level during sleep is approximately 94 to 98 percent, according to Sleep Apnea Guide. Levels below 90 percent oxygen saturation are dangerous to the human body. The human brain can only survive four minutes without oxygen before cell death occurs.
My oxygen saturation is always around 94% and falls to 80s% sometimes during sleep. My heart rate at many times during rest time will fall to 50s bpm and will feel short of breath and during sleep will go below 50 bpm causing me to wake up with adrenaline surges! Thanks. adrenaline.