Did you know when a dolphin sleeps it has one eye open? Not only that, half of its brain also keeps working so that it doesn’t forget to breathe while in water. This is interesting. Read more here https://www.mic.com/p/how-much-sleep-you-need-depending-on-your-age-78265688?utm_source=pocket-newtab-intl-en [The image is taken from www.mic.com]