The Circadian Variation of Psychophysiological Reactivity to Stress : A Study of Individual Differences
Abstract
The present study assessed the circadian variation of cardiovascular and affective reactivity to stress, and performance. Thirty-five healthy males and females were administered a series of tasks in a within-subject design with sessions counterbalanced at 7:30 a.m. and 3:30 p.m. on separate days. Affective responses were greater during the AM as demonstrated by higher self-reported levels of "frustrated". However, attention and cardiovascular responses appear to be greater during the PM. Marginally significant effects revealed that the Continuous Performance Test (CPT), a test of attention, yielded more correct responses and a faster reaction time during the PM session while the number of omissions were greater during the AM session. Cardiovascular levels were higher during the PM session for heart rate (HR) and marginally higher for rate pressure product (RPP) and systolic blood pressure (SBP). Changes from rest to task revealed greater cardiovascular reactivity during the PM session for diastolic blood pressure (DBP) and SBP. These measures were also examined for interactions between time of day and circadian type. Subjects were classified as Morning or Evening subjects based on the Morningness-Eveningness Questionnaire (Horne and Ostberg, 1976). Significant interactions were found for cardiovascular and affective measures in response to stress, but not for performance on the CPT. Overall, Morning subjects responded to stress more during the AM session whereas Evening subjects responded more during the PM session for levels of RPP and changes in RPP and SBP. Similarly, levels of "bored" and marginal levels of "interested", and changes in "bored", and marginal changes in "anxious", "frustrated", "happy", and "challenged" also interacted with circadian type. The existence of different patterns of stress responses depends upon circadian type and time of day and is discussed regarding methodological and health implications.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 25, 1994
- Accession Number
- AD1011358
Entities
People
- Linda Nebel
Organizations
- Uniformed Services University of the Health Sciences