Does a brief biofeedback exercise minimise the impact of acute stress on gastric function?

INTERVENTION: Participants will be required to attend a single 90‐minute session at Alimetry Ltd. The study involves a simple test, "like an ECT for the gut" that will run continuously for the duration of the session. Individuals will also have additional cutaneous electrodes and sensors placed on their hand and shoulders to capture heart rate variability, breath rate, temperature and perspiration. Recording for HRV and associated parameters will run continuously for the duration of the session. This process is painless and non‐invasive, although participants are asked to minimise movement. Participants will be asked to fast (not eat or drink anything including tea and coffee) from midnight the evening prior to their session and asked not to smoke or vape in the morning of their test. They may also be asked to refrain from taking some medications for 48 hours before their test. These medications include: drugs that affect gastric emptying (metoclopramide, domperidone, erythromycin), antispasmodics, pain medications which contain opiates (codeine, oxynorm, morphine, and tramadol), or sedatives. This is because these medications affect normal stomach actions. Upon arrival, eligibility will be reviewed and confirmed. Participants will be asked if they have any questions or concerns about the studies. Once these are satisfied, they will be required to sign an informed consent form and randomly assigned to either the intervention group (HRVB) or control group (sham procedure) The Body Surface Gastric Mapping (BSGM) recording will then be set‐up: ‐‐A guide will be used to locate the array in a personalised manner. A portable ultrasound may be used to verify this positioning system is accurate. ‐‐Excess hair will be removed and participant’s skin will be prepped CONDITION: Disorders of Gut‐Brain Interaction ;Functional Gastrointestinal Disorders; ; Disorders of Gut‐Brain Interaction ; Functional Gastrointestinal Disorders Mental Health ‐ Other mental health disorders Oral and Gastrointestinal ‐ Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon PRIMARY OUTCOME: Expected alterations in gastric myoelectrical activity for both the intervention group (HRV BIofeedback) and control group (sham procedure). [This will be facilitated by the continuous recording of gastric myoelectrical activity using body surface gastric mapping for the duration of the observation period which is approximately 90‐minutes. Five time point periods: ; (1) at baseline for a 10‐minute period; ; (2) during 20‐minute initiation phase of HRV Biofeedback or Sham Procedure before exposure to the stressor; ; (3) during 10‐minute washout period following initiation phase.; (4) during the cold pressor test for up to 3 minutes, and ; (5) 10‐minute period after cold pressor test. ] INCLUSION CRITERIA: 18+ years of age. Fluent in English. Are able to fully understand the risks and benefits of the research and provide informed consent. SECONDARY OUTCOME: Explore subjective experience across both conditions for the duration of the observation: ; How relaxed they feel. ; [Participants state of relaxation be measured using a visual analogue scale (VAS). They will be asked: ; How relaxed do you feel right now? Far left of scale is labelled "Not at all relaxed" and far right is labelled "Extremely relaxed". ; ; The researcher will administer this measure manually. Participants will be asked verbally how they feel. The researcher will use the VAS as guidance by moving a marker along the VAS from left Researcher will ask participant to say stop when are asked to mark on the scale how stressed they feel. The researcher will then mark the relevant point on the scale with an X. Timepoints of interest are outlined below: ; 1. At the beginning of the baseline period ; 2. At the end of the initial 10‐minute HRV Biofeedback/Sham Procedure. BEFORE Cold Pressor Test. ; 3. At the end of the Cold Pressor Test, when participant extracts hand voluntarily (up to 3‐minutes after initiation of Cold Pressor Test. ; 4. Participants are asked to continue HRV Biofeedback or sham procedure for 10‐minutes after Cold Pressor Test. The level of stress will be measured at the end of that 10‐minutes. ] Explore subjective experience across both conditions for the duration of the observation: ; How stressed they feel.[Participants state of stress will be measured using a visual analogue scale (VAS). They will be asked: ; How stressed do you feel right now? Far left of scale is labelled "Not at all stressed" and far right of scale is labelled "Extremely stressed". ; ; The researcher will administer this measure manually. Participants will be asked verbally how they feel. The researcher will use the VAS as guidance by moving a marker along the VAS from left Researcher will ask participant to say stop when are asked to mark on the scale how stressed they feel. The researcher will then mark the relevant point on the scale with an X. Timepoints of interest are outlined below: ; 1. At the beginning of the baseline period ; 2. At the end of the initial 10‐minute HRV Biofeedback/Sham Procedure, BEFORE Cold Pressor Test. ; 3. At the end of the Cold Pressor Test, when participant extracts hand voluntarily (up to 3‐minutes after initiation of Cold Pressor Test). ; 4. Participants are asked to continue HRV Biofeedback or sham procedure for 10‐minutes after Cold Pressor Test. The level of stress will be measured again at the end of that 10‐minutes. ] To examine fluctuations in HRV across both conditions.[This will be facilitated by continuous objective monitoring and recording of HRV signals and related parameters for the duration of the observation session. Five time point periods: ; (1) at baseline for a 10‐minute period; ; (2) during 20‐minute initiation phase of HRV Biofeedback or Sham Procedure before exposure to the stressor; ; (3) during 10‐minute wash‐out period after initiation phase. ; (4) during the cold pressor test for up to 3 minutes, and ; (5) 10‐minute period after cold pressor test. ] To measure pain intensity of participants when exposed to cold pressor test.[A numeric rating scale (NRS) will be used to measure the intensity of pain a participant feels during the cold pressor test. ; ; Participants will be asked how much pain they feel on an 11‐point Likert scale from 0= no pain to 10=the worst pain imaginable. ; ; The researcher will administer this measure verbally and circle relevant intensity as indicated by the participant. ; Three time points of interest: ; 1. When hand is immersed into the cold pressor test. ; 2. When hand has been in the cold pressor test for 1 minute. ; 3. When participant extracts hand from cold pressor test.]