Use of a non-invasive biomarker salivary alpha-amylase to assess the role of probiotics in sleep regulation and stress attenuation in surgical patients

Background and Aims: The influence of gut microbiota on human behaviour, stress and sleep is currently a novel topic of research. A prospective double-blind randomised trial was planned to find out whether probiotics by alteration of the gut microbiome can allay surgery-related stress and improve sleep. Methods: A total of 160 elective surgical patients were randomised to receive either probiotic or placebo capsule twice daily for four and a half consecutive preoperative days. They were subjected to the Perceived Stress Scale (PSS) questionnaire, a psychomotor vigilance task (PVT) and estimation of salivary alpha-amylase (SAA), a well-known biomarker of stress on the evening of admission and on the evening just before the day of scheduled surgery. Data were analysed using Chi-square test, Student's t -test and Mann–Whitney test. Results: On comparing between the two groups, there was a significant difference in PSS scores, SAA levels and PVT scores after probiotic/placebo therapy. There was a decrease in the PSS scores by 11.38% ( P < 0.05) and SAA levels by 11.38% ( P < 0.05) and an increase in the PVT scores (12.13%, P < 0.05) following probiotic treatment.There was a mean difference of 52.85 in SAA levels in probiotic group and − 69.32 in placebo group with a definite fall in SAA levels in probiotic group, which showed that these patients had reduced stress levels and improved psychomotor vigilance implying improved sleep. Conclusion: Gut microbiome alteration with probiotics results in lowering of psychological stress and sleep improvement in the preoperative period in surgical patients.