Sleep 101 [infographic] | Daily Infographic Sleep is absolutely necessary for human life. Almost every living creature requires some little bit of sleep to recharge for the next day ahead. As we slumber, different stages of sleep occur. And whether or not we wake up in the correct stage determines whether we feel rested the next day.
Sleeping sperm whales by Magnus Lundgren. Whales are voluntary breathers, so only half of their brain can sleep at any time - they have to think to breath! Scientists found this out the hard way when they tried to put a dolphin to sleep for an operation. Its whole brain was asleep so it could not think - it's time to take a breath!