Sleep, glorious sleep, still remains a bit of a mystery to scientists. However, if you’ve ever pulled an all-nighter, you’ll know all too well the effect a lack of sleep can have. Adults are recommended to get seven to eight hours of sleep every day, although it’s estimated that 30 percent of adults and 66 percent of adolescents in the United States are regularly sleep-deprived.

While any Monday morning can tell you that sleepiness can cause irritability and impaired brain function, prolonged and chronic sleep deprivation can also cause hormonal imbalances, physical illness, hallucinations, and even death.

But why is it so necessary? This video from TED-Ed gives you the low-down on the science behind sleep and why we need it so much.

^{Main image credit: Matthew Rice/Flickr. (CC BY-NC-ND 2.0)}