The term hypnotics has been applied to a group of substances capable of inducing sleep. A large number of these hypnotics are members of the methane series, or close derivatives. Their hypnotic action is directly comparable with that of alcohol, ether, or chloroform, but, by reason of the addition to the methane radical of different substances, other physiological actions may ensue which may modify to some extent the action of the primary substance.

As already intimated, practically the only alcohol used as a hypnotic is amylene hydrate. Its action resembles that of alcohol, but it induces narcosis more rapidly with smaller doses.