Acute and chronic stress increase salivary cortisol: a study in the real-life setting of a national examination undertaken by medical graduates

Figures & data

Table 1. Sampling days with activities and measured variables.

Sampling day	Variables measured	Activity of the participants
Day 1	Salivary cortisol at five time points. Psychological evaluation (STAI and PSS) n = 36	Study day plus mock examination* (16:00–21:00) at the academy.
Day 49	Salivary cortisol at five time points n = 36	Study day plus mock examination* (16:00–21:00) at the same location as for the official test. Participants were summoned at 45 min before the start of the examination, as in the official test.
Day 62	Salivary cortisol at five time points. Psychological evaluation (STAI and PSS) n = 36	Relaxation day. No mock examinations. No study.
Day 65	Salivary cortisol at 16:00 h only† n = 36	Official examination (16:00–21:00)*. No study.
Days 106–111	Salivary cortisol at five time points. Psychological evaluation (STAI and PSS) n = 8	10–15 days after receiving the national examination result and rank order

STAI, State-Trait Anxiety Inventory; PSS, Perceived Stress Scale.

*The mock and real examinations may represent acute stressors within the general stressor background of the examination preparation course.

†Only one sample was taken (at 30 min before the official examination) in order to minimize interference with the activities of the participants on this critically important day.

Table 2. Results (mean ± SD) obtained with the validated Spanish version of the State-Trait Anxiety Inventory (STAI). These values were compared with the reference values for the Spanish population using a one-sample Student’s t-test.

	Day 1	Day 1	Day 62	Day 62	Day 106–111	Day 106–111
	Males	Females	Males	Females	Males	Females
	n = 13	n = 23	n = 13	n = 23	n = 3	n = 5
STAI-State	25.77 ± 7.17	28.00 ± 8.64	27.07 ± 7.95	27.04 ± 6.95	19 ± 4	20.12 ± 4.21
	p = 0.022	p = 0.016	p = 0.017	p = 0.017	p = 0.317	p = 0.155
	t = 2.62	t = 2.60	t = 3.08	t = 2.58	t = −0.76	t = −1.58
STAI-Trait	25.38 ± 6.78	28.39 ± 6.56	29.61 ± 6.221	29.30 ± 7.51	18.33 ± 1.57	20.00 ± 1.60
	p = 0.021	p = 0.021	p = 0.000	p = 0.004	p = 0.131	p = 0.267
	t = 2.58	t = 2.48	t = 5.47	t = 3.21	t = −1.57	t = −2.17

In the male and female Spanish reference populations, threshold STAI-S values are 20.54 and 23.30, respectively, and threshold STAI-T values are 20.19 and 24.99, respectively. p = significance of the difference between the mean value and the reference Spanish value.

Figure 1. Salivary cortisol profile (mean ± SD) between 07:00 and 21:00 h on each sampling day. Cortisol concentrations are expressed in μg/dl; n = 36 for sampling days 1, 49, 62 and 65, n = 8 for sampling days 106–111. Statistically significant comparisons for same time of day: *p < 0.007 versus day 49; +p < 0.012 versus day 1; **p < 0.002 versus day 1; ***p < 0.001 versus day 49, day 65; +++p < 0.001 versus day 1, day 49. All possible pairwise comparisons, using the Bonferroni test, between the within-subject factor (salivary cortisol concentration) and the levels of each factor (sampling day).

Table 3. Cortisol Awakening Response (CAR) and Area Under the Curve (AUC) from salivary cortisol concentration measurements.

	Day 1 n = 36	Day 49 n = 36	Day 62 n = 36	Day 106–111 n = 8
Area under the curve (μg h/dl)	7.70 (±2.70)	8.82 (±3.47)	5.10 (±1.73)	2.63 (±0.88)
Cortisol awakening response (μg/dl)	0.124 (±0.104)	0.145 (±0.116)	0.078 (±0.119)	0.140 (±0.183)

Significant pairwise differences in AUC values (p < 0.001, Bonferroni test) were found between all sampling days. The CAR was only significantly different (p < 0.05, Bonferroni test) between days 49 and 62. Values are mean ± SEM.