Basic Concepts about Sleep and Insomnia

Abstract

In the 1870s, the English physician Richard Caton described spontaneous electrical activity in the brains of animals. The observation of these “feeble currents of the brain” was all the more remarkable in that it was done without the benefit of electronic amplification, which was not available for biological research for another 50 years (Brazier, 1973). Caton went on to observe that these electrical events could be altered by sensory stimulation, anaesthesia, and sleep (Schoenberg, 1974). It was not until 1929 that Hans Berger, a German psychiatrist, recorded similar phenomena from electrodes placed on the scalp of humans. Over the next 10 years, he reported that these recordings, which he referred to as electroencephalograms, changed with age and sensory stimulation, and were abnormal during epileptic seizures. Eight years after Berger’s original observations, Loomis, Harvey, and Hobart (1937) studied the first electroencephalographic recordings during human sleep. They reported that sleep is composed of several discontinuous stages, and speculated that their spontaneous changes were governed by “internal stimuli.” Although the descriptions have evolved over the years, the observation that sleep is composed of several recurring electrophysiologic stages remains an important principle in sleep research.