Somnology Somnology Somnology is the scientific study of sleep. It includes clinical study and treatment of sleep disorders and irregularities. Sleep medicine is a subset of somnology. After the invention of the EEG, the stages of sleep were determined in 1936 by Harvey and Loomis, the first descriptions of delta and theta waves were made by Walter and Dovey, and REM sleep was discovered in 1953. Sleep apnea was identified in 1965. In 1970, the first clinical sleep laboratory was developed at Stanford. The first actigraphy device was made in 1978 by Krupke, and continuous positive airway pressure therapy and uvulopalatopharyngoplasty
Sexual selection in humans penis towards larger size was the result of female choice rather than sperm competition, which generally favors large testicles. However, penis size may have been subject to natural selection, rather than sexual selection, due to a larger penis' efficiency in displacing the sperm of rival males during sexual intercourse. A model study showed displacement of semen was directly proportional to the depth of pelvic thrusting, as an efficient semen displacement device. There are a variety of factors that drive sexual selection in humans. Current available research indicates that selection preferences are biologically driven, that is, by the display of phenotypic