Types of Insomnia. There are two types of insomnia: primary insomnia and secondary insomnia. 1  Primary insomnia: Primary insomnia means that a person is having sleep problems that are not directly associated with any other health condition or problem.
System of a Down's music has variously been termed alternative metal, nu metal, hard rock, progressive metal, thrash metal, art rock and avant-garde metal.
Heavy metal (often referred to simply as metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in England and the United States.