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.
Progressive rock (often shortened to prog or prog rock) is a form of rock music that evolved in the late 1960s and early 1970s as part of a mostly British attempt to elevate rock music to new levels of artistic credibility..