The aroma of camphor seems to be very effective for a particular type of nervous depression where great agitation precedes a loss of energy and stamina and a feeling of deep despair.
Camphor has been used, in dilution, to stimulate circulation, metabolism, and digestion. Camphor is also a strong disinfectant and decongestant. It has a reputation as anti-inflammatory and as a pain reliever. I find the aroma and the list of cautions of camphor oil daunting, and personally, almost always use something else instead.