From the 1940s to 1985, Calvin S. Hall collected more than 50,000 dream reports at Western Reserve University. In 1966 Hall and Van De Castle published The Content Analysis of Dreams in which they outlined a coding system to study 1,000 dream reports from college students. It was found that people all over the world dream of mostly the same things. Hall’s complete dream reports became publicly available in the mid-1990s by Hall’s protégé William Domhoff, allowing further different analysis.
The Hall data analysis shows that sexual dreams occur no more than 10% of the time and are more prevalent in young to mid teens. Another study showed that 8% of men’s and women’s dreams have sexual content. In some cases, sexual dreams may result in orgasm or nocturnal emission. These are commonly known as wet dreams.
While the content of most dreams is dreamt only once, many people experience recurring dreams — that is, the same dream narrative is experienced over different occasions of sleep. Up to 70% of females and 65% of males report recurrent dreams.
Color vs. black and white
A small minority of people say that they dream only in black and white.