Methodology in clinical sleep research.

This review presents traditional and cutting-edge interventions in sleep research, including descriptions of the relationship of rapid eye movement-non-rapid eye movement sleep with the autonomous nervous system, and dream research methodology. Although sleep and dreaming are overlapping and non- separable phenomena, they are not typically addressed simultaneously in the scientific sleep research literature. Therefore, a more extensive overview of dream research has been included with a focus on objective dream content analysis and the theory of neurocognitive analysis. A bridge is made between dream content analysis and current sleep research methodologies.