The goal of this clinical trial is to learn if a mindfulness booster course can reduce stress in healthcare staff who have previously attended a mindfulness course. The main questions it aims to answer are:

• Is a mindfulness booster course for healthcare staff effective at reducing their stress levels?
• Are any benefits maintained for 8 weeks?

Researchers will compare a mindfulness booster course with usual care to see if it helps to reduce stress. Participants will take part in either a mindfulness booster course or do what they usually do to look after their wellbeing. They will complete questionnaires at the beginning, middle and end of the study.

Aims:

1. To determine whether the mindfulness booster course for healthcare staff is effective in terms of the primary outcome (perceived stress) and secondary outcomes (wellbeing, depression, burnout, and compassion for others), and whether any benefits are maintained at follow-up.
2. To examine whether any effects on the above-mentioned outcomes are statistically mediated by changes in amount of mindfulness practice, rumination and worry, decentering, self-compassion, and trait mindfulness.
3. To develop an abbreviated grounded theory of the therapeutic process and outcomes of the mindfulness booster course.

Hypotheses:

1. a) The primary hypothesis is that we will see a significantly greater decrease in the primary outcome of perceived stress at post-intervention (the primary time-point of Weeks 11-12) relative to baseline (Weeks 0-1) for the 'mindfulness-booster course plus treatment as usual (TAU)' intervention group compared to the 'TAU-only' control group.

   b) Our secondary hypothesis is that we will see significantly greater improvements in each of our secondary outcome measures at post-intervention (Weeks 11-12) relative to baseline for our intervention group compared to our control group. Improvements entail decreases in depression and burnout and increases in compassion for others and wellbeing.

   c) Our third hypothesis is that we will also see the effects detailed in (1a) and (1b) above at the follow-up time-point (Weeks 19-20).

2. a) The relationship between group allocation (intervention vs. control) and reduction in perceived stress, from baseline to follow-up (Weeks 19-20), will be statistically mediated by changes from baseline to post-intervention in the following psychological constructs: i) increase in amount of mindfulness practice, both formal and informal; ii) reduction in rumination and worry, i.e., repetitive negative thinking; iii) increase in decentering; iv) increase in self-compassion; v) increase in trait mindfulness.

   b) The relationships specified in Hypothesis 2a will also hold true for the secondary outcomes (i.e. change from baseline to follow-up [Weeks 19-20] in wellbeing, depression, burnout and compassion for others).

   c) i) The relationship between group allocation and reduction in perceived stress will be serially statistically as follows: intervention group allocation predicts increased mindfulness practice (from baseline to post-intervention [Weeks 11-12]) which in turn predicts change in psychological mechanisms (i.e., rumination/worry, decentering, self-compassion and trait mindfulness; from baseline to post-intervention [Weeks 11-12]), which in turn predict reduced perceived stress (from baseline to follow-up [Weeks 19-20]).

   ii) The relationships specified in Hypothesis 2c-i will also hold for the secondary outcomes (i.e. change from baseline to follow-up [Weeks 19-20] in wellbeing, depression, burnout and compassion for others).

   Design Information Not Included Elsewhere in this Registration:

   After Weeks 11-12, a subsample of intervention group participants will be invited to participate in a semi-structured individual interview, with the qualitative data being collected and analysed according to grounded theory principles. This aspect of the study has the following sub-aims:

   1. To explore what processes occur during the mindfulness booster course, based on participants' experiences.
   2. To explore how these processes interact with the participants' contexts, including, but not limited to, working in healthcare.
   3. To explore how these processes and contexts interact with, and perhaps drive, any perceived impacts and outcomes of the course.

Inclusion Criteria:

• UK National Health Service staff member.
• Has completed an 8-week mindfulness course (either MBCT, MBCT-L or MBSR). Individuals will be considered to have "completed" a mindfulness course if they attended four or more sessions.
• Is able to make one of the planned sets of times for the booster course sessions, in case they are randomly allocated to the intervention arm.

Exclusion Criteria:

• Currently on sick leave.
• Planning on undertaking another 8-week mindfulness course.
• Previously participated in the mindfulness booster course in the feasibility study.
• Have previously found practising mindfulness distressing.

All outcome measure IPD will be made publicly available. Some or all demographic IPD may be excluded to prevent jigsaw identification of participants. An assessmment of what, if any, demographic IPD can be included will be made once the data have been collected and the risk of participant identification assessed.

These will be made available after the study findings have been published in peer reviewed journals and, in any event, no more than 3 years after study completion.

These will be made publicly available on the internet at access at https://pure.canterbury.ac.uk/en/persons/fergal-jones-2/