At night whilst you sleep your body is able to repair and grow as the pituitary gland releases growth hormone. Your nerve cells are active, communicating and reorganizing to support healthy brain function.
The brain also uses this time to file, filter and store new information and clear out any toxic waste. In fact, according to a news article by the BBC, a team of US researchers completing a sleep study reported that "the 'waste removal system' was one of the fundamental reasons for sleep".
Their study, which looked at the brain function during sleep, identified that when asleep our cells shrink, opening gaps between neurons and allowing fluid to wash the brain clean!
The study also raised the question as to whether failing to clear away some toxic proteins could be a contributing factor to brain disorders.