Sleep Cycling

The only organ that needs to sleep is the brain, Some hormones, such as adrenaline, make us feel more alert and prepared for action. This then makes it hard for us to go to sleep and even then it is still quite active. When blood is needed in a prioritized manner in certain areas of the body, for example during a marathon the muscles and the heart need more oxygen There is no organ that sleeps. The brain as a whole is highly active during sleep, even secreting certain hormones predominantly during that time.