The Association Of Limbic System Activation With Dream, Bad Dream And Nightmare Generation

ABSTRACT

Despite the fact that nightmares occur with regularity in the general population, most

previous research has focused on clinical samples, and the genesis of idiopathic

nightmares remains poorly understood. The aim of the present research was therefore

to investigate the neuropsychological mechanisms of idiopathic bad dream and

nightmare generation, with a particular focus on the limbic system. High versus low

levels of limbic activation and its effect on the frequency of dream, bad dream, and

nightmare recall, characteristics, and content were investigated using retrospective and

prospective measures. Psychosocial stress – a phenomenon which increases activity in

the limbic system – and its relationship to bad dreams and nightmares was also

investigated, using questionnaires and a prospective dream diary study. Oral

contraceptive use was included as a moderator variable as previous research has

indicated that this may temper reactions to stress. The general hypothesis that greater

activation of the limbic system results in a greater frequency of recall of bad dreams and

nightmares, and also results in more negative dream content, was confirmed. It was also

found that external factors which increase limbic activation such as psychosocial stress

lead to a greater recall of bad dreams and nightmares. Although oral contraceptive use

did not moderate the relationship between stress and bad dream and nightmare recall

frequency, more generally positive dream content was found in users of oral

contraceptives compared to non-users. Taken together, the results of the studies

indicate that similar neuropsychological mechanisms may underlie the formation of

idiopathic nightmares and nightmares in clinical conditions, and also that increased

levels of limbic activation may result most commonly in negative dream content.