Background/Aims: The purpose of this within-subjects feasibility study was to determine whether two different homeopathic remedies, Nux Vomica (NV) and Coffea Cruda (CC), exert effects on subjective mood ratings in healthy adults with a history of coffee-induced insomnia. The impact of individual personality traits, anxiety sensitivity or Type A cynical hostility, and homeopathic constitutional type (HTYPE-NV, HTYPE-CC), on remedy effects was examined to evaluate differential responsivity, in accord with clinical claims. Subjects and Methods: Young adults of both sexes (ages 18–31) with above-average scores on standardized personality scales for either cynical hostility or anxiety sensitivity, and a history of coffee-induced insomnia, participated in the month-long study. At-home polysomnographic recordings were obtained on successive pairs of nights once per week for a total of 8 recordings (nights 1, 2, 8, 9, 15, 16, 22, 23). Subjects (N = 59) received placebo pellets on night 8 (single-blind) and verum pellets in 30c doses of one of two homeopathic remedies, NV or CC, on night 22 (doubleblind). Subjects completed the Profile of Mood States Scales at bedtime. Results: The remedies produced differential effects on anger and overall mood, with improved mood following CC administration. A similar trend for depression was observed. Anxiety sensitive subjects experienced less tension following CC, whereas hostile subjects receiving CC became more tense. The high HTYPE-CC receiving CC experienced less vigor. The high HTYPE-CC receiving NV experienced more vigor.