Sleep is composed of four stages, the deepest of which are known as slow-wave sleep and rapid eye movement.
Нойр нь 4 үе шатаас бүрдэнэ. Хамгийн гүн нойрны үе нь удаан долгионы үе болон нүдний хурдан хөдөлгөөний үе юм.