Chronic stress exposure decreases the cortisol awakening response in healthy young men

Figures & data

Table 1. Descriptive statistics by group: mean (SD).

	Exam group (n = 42)	Control group (n = 21)
Age (in years)	22.54 (0.98)	22.51 (1.05)
Education (in years)	15	15
PSS10*	17.16 (2.53)	14.90 (4.71)
STAIt**	64.64 (12.53)	53.81 (10.22)
Sleep duration (in hours)**	6.95 (0.75)	7.80 (0.64)
Average wake up time**	07:04 (29 min)	07:28 (35 min)
Review duration (in months)	6.15 (2.44)	–
Review intensity (hours/day)	9.56 (1.56)	–

PSS10 = Perceived Stress Scale (10-item) score; STAIt = State and Trait Anxiety Inventroy – total score. SD, standard deviation.

*p < 0.05; **p < 0.01.

Table 2. Mean cortisol values over two days by group: mean (SE) nmol/L.

	Exam group (n = 42)	Control group (n = 21)
S1	15.13 (1.24)	14.76 (1.01)
S2	16.43 (1.23)	16.70 (1.26)
S3	16.02 (0.89)	18.01 (1.52)
S4	12.57 (0.61)	13.39 (0.97)
R30**	1.07 (0.86)	5.15 (0.86)
AUCg	15.13 (0.84)	15.88 (1.05)
AUCi *	0.18 (0.70)	3.02 (0.94)

S1, S2, S3 and S4 represent cortisol concentration at awakening and 15 minutes, 30 minutes, 60 minutes thereafter respectively; R₃₀, cortisol increase in 30 minutes after awakening; AUC_g, area under the curve with respect to the ground; AUC_i, area under the curve with respect to the increase.

*p < 0.05; **p < 0.01.

Figure 1. Mean awakening cortisol levels over two days in high-stress exam (n = 24), low-stress exam (n = 18) and nonexam (n = 21) groups. The x-axis represnets time points of saliva sampling, and the y-axis represent averaged raw cortisol levels across two days. Error bars represent the standard error of the mean.

Figure 2. Values of four different CAR measures over two days in the high-stress exam group (n = 24), low-stress exam group (n = 18) and nonexam group (n = 21). The graph shows mean value, with error bars representing the standard error of the mean. *p < 0.05; **p < 0.01.

Table 3. Bivariate correlations.

	PSS10	STAIt	S1
STAIt	0.64**
S1	0.12	0.21
R30	−0.30*	−0.30*	−0.54**
AUCg	−0.05	0.04	0.77**
AUCi	−0.26*	−0.30*	−0.67**

*p < 0.05, **p < 0.01.