Enervate

Enervate: In general use, enervate means to weaken and demoralize. In medicine, it means to remove nerve cells - an excellent way to remember the meaning. Do no confuse it with its antonym: energize.

When he saw it close-up, Jack found true poverty enervating.

A Book for Today: Contagion by Robin Cook

During the past year Blomkvist had often regretted that they hired Dahlman, who had the enervating habit of looking at everything in as negative a light as possible.