Stress: Common themes toward the next frontier.

"Stress is complicated". A phrase uttered by many a stress researcher. This is true, from the vast array of stimuli considered "stressors" to the interactive and hormetic nature of the molecular, cellular, endocrine, and behavioral responses generated by such stressors. This commentary takes the position that stress researchers are poised to make even bigger contributions if they begin to shift from investigating the myriad effects of stress on brain and body, and to refocus a larger part of our efforts on more in-depth investigations of common themes in stress biology, with the goal of uncovering potential "universal principles" of stress that may help us better interpret the findings at higher levels of analysis, and provide a structured approach to help breach the next frontiers of stress research.