Abstract
The study aimed to determine how different baseline states of mind in each day (relaxed, ordinary, or stressful) affected the diurnal patterns of three commonly investigated salivary stress biomarkers: cortisol (sCort), alpha-amylase (sAA), and chromogranin A (sCgA). A total of 32 healthy volunteers collected saliva on three different mood days at six time points each day (awakening, 30 min after, 10:00, 12:00, 16:00, and 19:00 h). Pulse rates and subjective feeling of stress using a visual analog scale (VAS) were also recorded. The levels of sCort and sAA were highest on a stressful day at certain time points. The levels of sAA were lowest on a relaxing day in the afternoon. Surprisingly, sCgA levels showed an opposite pattern with the highest level seen on a relaxing day. Of note was that the majority of the participants chose a day during a meditation retreat as their relaxing day and participants practicing mindfulness manifested lower levels of sCort (p = 0.003) and sAA (p = 0.043) at 19:00 h compared with those choosing a general leisure day as their relaxing day. Different states of mind were associated with different courses of salivary stress biomarkers. sCort and sAA are the most reliable markers showing the expected trend with higher levels on a stressful day and lower levels on a relaxing day. While the current result cast doubt on the use of sCgA as a stress marker since it was the only marker that showed the opposite trend compared with those of the other two markers as well as pulse rates and VAS. Furthermore, this is the first study to demonstrate that mindfulness practice might have different effects on these biomarkers from just a general relaxed state of mind.