Although stress has been described as a non-specific psychophysiological response to environmental stimuli, it is possible to discern specific bodily stress responses caused by specific emotional reactions to novel, ambivalent or uncontrollable situations and stimuli. For example, social stress induces elevated cortisol levels, particularly if the stressor is uncontrollable, unpredictable, and constitutes a social-evaluative threat due to the judgment of others such as in the Trier Social Stress Test). Usually, the TSST induces a two-fold increase in saliva cortisol with peaks around 10-20 min. after stress test termination. Also, an average increase in heart rates of around 20 beats per minute (bpm) is observed during the TSST. In addition, emotional states and feelings have been shown to be affected by this stress test, such as marked increases in stress perception,anxiety and emotional insecurity as well as decreases in mood, calmness and feeling awake.