Straight jackets were historically used to prevent individuals from harming themselves or others in asylums during the 17th and 18th centuries, providing a humane alternative to chaining patients to beds. However, with changing attitudes towards mental illness treatment, especially highlighted by King George III's case, straight jackets gradually fell out of favor as the concept of curing mental illnesses emerged. The successful treatment of King George III marked a revolutionary shift in the approach to mental health care, paving the way for more progressive methods of treatment and the eventual decline of straight jackets in mental health practices.