Fig. 1. Changes in reflex threshold (Tr, upper panel) and subjective pain threshold (Tp, lower panel) during the follicular and the luteal phases in 14 healthy women. Thin lines illustrate single-subject variations, while the thicker line represents the mean value. The shaded gray areas located on the extremes of the thicker line represent the standard deviation limits. Student’s t test for paired data: follicular vs. luteal phase p< .05 for both Tr and Tp.