The effect of mood, the common cold, amount of sleep, and sunshine on recurring herpes simplex virus (HSV) infection was investigated using daily self-reports over a 3-month period from 23 female and 15 male patients with genital herpes and 26 female and two male patients with oral herpes. Results showed recurring genital HSV infection to be preceded by reduced and decreasing overall emotional well being over a period of 10 days, with a temporary improvement in the middle of the period. This pattern was significantly represented by rated nervousness and rated alertness. Females showed more marked trends for reported mood than did the males, which could not be attributed to the menstrual cycle. Conversely, males showed a more marked, strongly significant fourth-order trend for reported amount of sleep, with nadirs on the 8th and the 3rd day before the recurrence. Neither exposure to sunshine nor the common cold showed any relation to recurrence of genital HSV infection. The common cold appeared as the major precipitating factor in oral herpes. Except for a significant fourth-order trend for rated alertness, no relationship between mood and subsequent onset was found. This negative finding was interpreted as a masking effect of the common cold. Two alternative physiological theories, the ganglion trigger theory and the skin trigger theory, were discussed in relation to present findings. It was suggested that various possible mediators between mood states and recurring herpes should be investigated using the present approach, with structured diaries as complement to the rating scales.