Figure 3.
Serum cortisol levels prior to and during sleep comparing results from two studies, stratified into HC (N=31 Study A, N=24 Study B) and IBS (N=30 Study A, N=42 Study B). Vertical intervals show geometric means and 95% confidence intervals. Note that the values on the ordinate are shown in linear measurement units, but are plotted on an axis with logarithmic spacing. Study A = prior study, with no threat of public speaking; Study B = current study, with threat of public speaking but otherwise similar to study A; IBS = Irritable Bowel Syndrome; HC = Healthy Controls; * = p-value < 0.05, ** = p-value < .01, from ANCOVA controlling for age and body mass index.