All of us are stressed, every now and then. Acute stress can have a profound impact on the human body and mind: both physical and psychological stressors affect the autonomic nervous system and the hypothalamic–pituitary–adrenal axis, leading to changes in cardiovascular and neuroendocrine measures. Stress also is shown to affect cognitive functions like memory and attention. Just recently, however, research discovered that acute stress also can influence our moral behaviour.

In a fascinating study, published in ‘Psychological Science’, 34 male participants were put under acute stress by using a standardized psychological stressor, well-established in stress research. Compared to the not stressed control group, the stressed participants not only showed physiological responses like increased heart rate and a higher levels of the ‘stress hormone’ cortisol – they also behaved more pro-socially. When offered to either share some money they got with another participant or to keep all for themselves, the stressed participants shared more. They also acted in a more trustworthy manner and were willing to trust others more themselves.

Another study, published in ‘Psychoneuroendocrinology’ this month, suggests that this phenomenon cannot be transferred to altruistic behaviour in general: participants under acute stress did not donate more money to an anonymous charity than their unstressed counterparts. Apparently, being confronted with an actual other person is necessary for stress to increase pro-social behaviour. An explanation might be that people under acute stress behave more pro-socially towards their peers in order to seek their comfort and support (‘tend and befriend hypothesis’).

When thinking about stress, most of us have its negative effects in mind like unpleasant emotions and health problems. Who would have thought that acute stress can serve the moral good?