sensational adj.

1610s, "a reaction to external stimulation of the sense organs," from French sensation (14c.) and directly from Medieval Latin sensationem (nominative sensatio) "perception," from Late Latin sensatus "endowed with sense, sensible," from Latin sensus "feeling" (see sense (n.)).

The general sense of "action or faculty of receiving a mental impression from any affectation of the body" is attested in English by 1640s.

The great object of life is sensation — to feel that we exist, even though in pain. It is this 'craving void' which drives us to gaming — to battle, to travel — to intemperate, but keenly felt, pursuits of any description, whose principal attraction is the agitation inseparable from their accomplishment. [Lord Byron, letter, Sept. 6, 1813]

 The meaning "state of shock, surprise, or excited feeling or interest in a community" is recorded by 1779. Meaning "that which produces excited interest or feeling in a community" is by 1864.

1846 in philosophy, "theory that sensation is the only source of knowledge and ideas;" 1865 in reference to journalism, "writing or language that aims to excite the feelings," from sensational + -ism. Sensation novel is attested by 1856 (Wilkie Collins's often are cited in early examples).

Sensation novels, novels that produce their effect by exciting and often improbable situations, by taking as their groundwork some dreadful secret, some atrocious crime, or the like, and painting scenes of extreme peril, high-wrought passion, etc. [Century Dictionary]