So, in other words, a biological stressor without a psychological component.

换句话说，没有掺杂心理因素的生物压力。

But there may also be a psychological component. The stress of a recession can make people less likely to bare their arms.

但这也可能有心理因素：经济下滑所造成的压力使人们更不愿意伸出胳膊献血。