Dose-Response Effects of Mindfulness Meditation

The goal of this randomized controlled trial is to test for evidence of dose-response effects in a sample of healthy adults with little to no prior experience with meditation. The main question it aims to answer is whether larger doses of mindfulness meditation yield greater positive changes in wellbeing than smaller doses. Our hypotheses are that (1) larger doses of mindfulness training will yield significantly larger effects, and (2) different doses will be significantly associated with variation in participant engagement, with lower engagement associated with higher doses. Researchers will compare each of three dose conditions, 10-min, 20-min, 30-min, against a minimal dose condition of 3-4 min. Participants will take a 28-day mindfulness meditation course, with guided audio instructions provided daily throughout the intervention period (excluding one rest day per week). They will also be asked to respond to surveys before, during, and after the intervention.

The study will compare the efficacy of receiving different "doses" of mindfulness training over a 28-day period in a prospective 4-armed, parallel-group randomised controlled trial. Participants will be randomised into one of the 4 groups: 10 minutes of meditation per day, 20 minutes of meditation per day, 30 minutes of meditation per day, or a minimal dose of 3-4 minutes of meditation per day. All participants will be encouraged not to complete any further mindfulness training or practice during the intervention period, apart from informal practice during daily life. Self-reported biopsychosocial measures will be evaluated at four time points; before randomization (baseline; T0), 2 weeks after randomisation (mid-intervention, T0.5), 4 weeks after randomization (post-intervention; T1), and 2 months after randomization (post follow-up; T2). In addition, weekly and daily outcomes will be evaluated between T0 and T1. Individual adherence and meditation-related experiences (including adverse events) will be monitored and compared across treatments. The trial will consist of three main phases: the Run-in Period, the Intervention Period, and the Follow-up period, as described below.

Inclusion Criteria: * Reside in Australia, with no plans to relocate or travel overseas during the intervention period; * Sufficient comprehension of the English language to complete measures; * Register for an account and agree to the Terms and Conditions of Unforgettable.Me; * If suffering anxious or depressive symptoms of moderate severity (defined by \> 19 on the Patient-Reported Outcomes Measurement Information System \[PROMIS\] Level 2 Anxiety or \> 22 on the PROMIS Level 2 Depression), must agree to continue recommended routine medical treatment for eligible underlying mental and/or physical health conditions or the duration of the study and to seek additional treatment if indicated by deterioration of symptoms; * No or minimal experience with meditation, defined as less than 25 hours over the past 6 months; never attended a multi-day mindfulness course (e.g., Mindfulness-Based Stress Reduction, Vipassana). If 50% of our target sample size has not bee recruited within the first three months of active recruitment, the inclusion criteria will be broadened to include participants with up to 100 hours in the past 6 months. Exclusion Criteria: * Self-reported current or lifetime serious mental illness (e.g., neurodevelopmental, schizophrenia spectrum, bipolar, obsessive-compulsive, trauma-related, dissociative or personality disorder); * Anxious and depressive symptoms in the severe range (defined by \>27 on the PROMIS Level 2 Anxiety or \> 32 on the PROMIS Level 2 Depression); * Psychological distress symptoms in the severe range (Kessler Psychological Distress Scale \[K10\] \>= 30); * Threshold scores on pre-screening and follow-up measures exceeded for Mania, Suicidal Ideation, Psychosis, Repetitive Thoughts \& Behaviors, Dissociation * Moderate alcohol, tobacco, or drug use; * Self-reported diagnosis of neurological condition (e.g., traumatic brain injury, amnesia, epilepsy, stroke, etc.); * Self-reported presence of any serious medical condition (e.g., cancer, thyroid disorder, multiple sclerosis, etc.); * Recent bereavement or major loss; * History of unexplored, untreated traumatic experiences or adverse childhood events.