The authors exposed 10 healthy human volunteers to the stress of loud
(100 dB) noise under controllable and uncontrollable conditions on two
separate days. Subjects reported higher self-ratings of helplessness, lack
of control, tension, stress, unhappiness, anxiety, and depression; had
greater hypothalamic-pituitary-adrenal axis function as measured by
elevations in plasma adrenocorticotropic hormone; and had higher levels of
sympathetic nervous system and electrodermal activity after the
uncontrollable stress condition than after exposure to controllable stress.
Thus, lack of control over even a mildly aversive stimulus can produce
alterations in mood as well as neuroendocrine and autonomic nervous system
changes in healthy subjects.