The investigators are conducting a randomised-controlled trial comparing coherent breathing at ~5.5 breath cycles per minute-bcpm (with equal inhalation/exhalation durations of ~5.5secs each) to a well-designed placebo (paced breathing at 12bcpm with equal inhalation/exhalation durations of 2.5secs each). The metric of 12bcpm is in line with guidance from the British Journal of Nursing, Royal College of Physicians, and Johns Hopkins University which state that the average, healthy bcpm should range from: 12-20bcpm, 12-18bcpm, and 12-16bcpm, respectively, hence the investigators chose the minimum/lower bound for the active placebo control group. The main questions that our study attempts to address are: Does coherent breathing (and placebo coherent breathing) lead to improved mental health and wellbeing in a general population adult sample?

The study will be conducted entirely online through the research platform Prolific, so participant data will be anonymous. The investigators will collect self-reports of mental health and wellbeing before and after the four-week breathwork period, along with a follow-up one-month later. Pre-post intervention and follow-up questionnaires will be completed online via the survey platform Qualtrics which will be linked to Prolific. Participants will also be asked how many times they practiced out of the assigned 28 days, to gauge self-reported adherence to the protocol. The investigators can then observe whether self-reported adherence correlates with changes in mental health and wellbeing, if any. Data on the self-reported credibility/expectancy of the breathwork randomly allocated to participants will also be collected, along with open-ended responses on participants' overall experience of the protocol/study.

Inclusion Criteria (self-assessed):

• 18+ years of age (18 is the automatic minimum age on Prolific)
• Able to breathe through nose
• Have access to headphones
• The following pre-screeners on Prolific will also be set so only those eligible on Prolific will see the study: Located/living in UK, Fluent in English, approval rate of 98% and at least 20 previous submissions (as recommended by Prolific to increase retention and reduce dropout rates in longitudinal and multi-part studies)

Exclusion Criteria (self-assessed):

• Any problems which affect ones ability to pace their breathing (i.e., active/chronic respiratory infection including blocked nose/cough/cold/fever, etc.), breathlessness, cardiovascular problems, respiratory conditions or diseases (i.e., uncontrolled symptomatic asthma, COPD, lung cancer, etc.), abnormally slow breathing (bradypnea), or abnormally fast breathing (tachypnoea)
• Any other physical/mental health conditions or current life events which impair or affect ones ability to engage in activities involving breath control

All participant data will be anonymous (only Prolific user IDs will be seen). No identifiable personal information will be collected. Participants will be able to check a box if they are happy for our research team at the University of Sussex to include the data again in future studies related to breathwork and meditation if these have gained independent ethically approval, based on the strict confidentiality terms described in the participant info/consent form.

Indefinitely after the study has been completed.

Our research team at the University of Sussex will have access. The datasets used and/or analysed during the current study will be available from the principal investigator on reasonable request to other researchers working on meditation and breathwork.