Because dreams are so subjective, they frustrate the methods of objective, empirical science—we have nothing like a “dream microscope” that allows us to observe the dreams unfolding within the sleeper’s mental field. Despite some important precursors, modern laboratory-oriented dream research did not really get off the ground until after Eugene Aserinsky and Nathaniel Kleitman’s 1953 discovery of rapid eye movement (REM) sleep and the subsequent linking of REM sleep with dreaming. Although later studies showed that significant dreaming could take place during non-REM sleep, the postulate that there was a close correlation between dreams and REM sleep guided scientific dream research for over a decade. While sleep labs had existed prior to 1953, the rapid expansion of the field of sleep and dream research in the wake of the discovery of REM sleep stimulated the establishment of more such laboratories as well as the expansion of existing ones.
A typical sleep lab consists of a number of separate rooms where experimental subjects sleep and an instrumentation room where data from various measuring devices are recorded. In most cases, the data being collected are bioelectrical in nature, and a device called a polysomnograph records ongoing variations in the sleeper’s bioelectrical state. The two primary measures are EOG (electro oculogram, which records eye movements, the primary indicator of REM sleep) and EEG (electroencephalogram, which records brain waves, used to determine the sleeper’s stage of sleep). Depending on the data being gathered, other instruments might include a closed-circuit TV, a tape recorder, devices for measuring respiration, and so on.
Subjects may be paid or may be students earning credit for one of their classes, usually a psychology course. Participants arrive several hours beforehand to fill out forms and to have electrodes or other instruments attached. Often a physical examination is also conducted. Usually the first night of sleep is atypical because one tends not to sleep as well in a new environment. Depending on the nature of the experiment, the data from this first night might be thrown out or ignored.