Stress System Dynamics during “Life As It Is Lived”: An Integrative Single-Case Study on a Healthy Woman

Little is known about the dynamic characteristics of stress system activity during “life as it is lived”. Using as representative a study design as possible, this investigation sought to gain insights into this area. A healthy 25-year-old woman collected her entire urine over a period of 63 days in 12-h intervals (126 measurements) to determine cortisol and neopterin (immune activation marker) levels. In addition, she filled out questionnaires on emotional state and daily routine in 12-h intervals, and was interviewed weekly to identify emotionally negative and positive everyday incidents. Adjusted cross-correlational analyses revealed that stressful incidents were associated with cyclic response patterns in both urinary cortisol and urinary neopterin concentrations. Urinary cortisol levels first decreased 12–24 h after stressful incidents occurred (lag 1: −.178; p = 0.048) and then increased a total of 72–84 h later (lag 6: +.224; p = 0.013). Urinary neopterin levels first increased 0–12 h before the occurrence of stressful incidents (−lag 1: +.185; p = 0.040) and then decreased a total of 48–60 h following such stressors (lag 4: −.181; p = 0.044). Decreases in urinary neopterin levels were also found 24–36 and 48–60 h after increases in pensiveness (lag 2: −.215; p = 0.017) and depressiveness (lag 4: −.221; p = 0.014), respectively. Findings on emotionally positive incidents sharply contrasted with those dealing with negative experiences. Positive incidents were followed first by urinary cortisol concentration increases within 12 h (lag 0: +.290; p = 0.001) and then by decreases after a total of 60–72 h (lag 5: −.186; p = 0.039). Urinary neopterin levels first decreased 12–24 h before positive incidents occurred (−lag 2: −.233; p = 0.010) and then increased a total of 12–24 h following these incidents (lag 1: +.222; p = 0.014). As with previous investigations on patients with systemic lupus erythematosus (SLE), this study showed that stress system response can be considerably longer and more complex and differentiated than findings from conventional group studies have suggested. Further integrative single-case studies will need to be conducted in order to draw firm conclusions about stress system dynamics under real-life conditions

Adjusted cross-correlation functions indicating that positive incidents related to “educational and/or social accomplishment” are associated with cyclic responses in urinary cortisol and urinary neopterin levels.

<p>Each lag represents a time interval of 12 h. Coefficients (bars) reaching the upper or lower confidence limits (lines) are significant at <i>p</i><.05. In <b>A</b>) positive incidents are followed by urinary cortisol concentration increases at ±lag 0 (0–12 h) and decreases at +lag 5 (60–72 h). In <b>B</b>) positive incidents are precipitated by urinary neopterin level decreases at −lag 2 (12–24 h) and followed by urinary neopterin level increases at +lag 1 (12–24 h).</p

Examples of “somewhat, moderately, and marked stressful” daily incidents.

<p>Examples of “somewhat, moderately, and marked stressful” daily incidents.</p

Adjusted cross-correlation functions indicating that negative (“somewhat, moderately, and marked stressful”) incidents are associated with cyclic responses in urinary cortisol and urinary neopterin levels.

<p>Each lag represents a time interval of 12 h. Coefficients (bars) reaching the upper or lower confidence limits (lines) are significant at <i>p</i><.05. In <b>A</b>) negative incidents are followed by urinary cortisol concentration decreases at +lag 1 (12–24 h) and increases at +lag 6 (72–84 h). In <b>B</b>) negative incidents are preceded by urinary neopterin level increases at −lag 1 (0–12 h) and followed by urinary neopterin level decreases at +lag 4 (48–60 h).</p

Time series of urinary cortisol and urinary neopterin levels of the healthy woman under study.

<p><b>A</b>) shows the time series of urinary cortisol levels, and <b>B</b>) shows the time series of urinary neopterin levels. Both the raw data (solid black) and the fit from the ARIMA model representing the series' internal structure (dotted grey) are plotted. Time series cover a period of 63 days or 126 12-hour time-units during which the subject collected her entire urine in day portions (08:00–20:00 h, uneven numbers) and night portions (20:00–08:00 h, even numbers).</p