Intermittent mindfulness practice can be beneficial, and daily practice can be harmful. An in depth, mixed methods...

Despite a weak evidence base, daily use of mindfulness-based self-help smartphone applications (apps) is said to promote wellbeing. However, many do not use these apps in the way that app developers and mindfulness proponents recommend. We sought to determine whether the "Calm" app works, and whether it does so even when it is used intermittently.

Employing a mixed-methods design, we recruited a self-selected sample of 269 students from a Scottish university (81% female, 84% white, mean age 23.89) to engage with a seven-day introductory mindfulness course, delivered using Calm, currently one of the most popular, yet under-researched, apps.

Daily course engagement was associated with significant gains in wellbeing (p ≤.001, d = 0.42), trait mindfulness (p ≤.001, d = 0.50) and self-efficacy (p ≤.014, d = 0.21). Intermittent course engagement was also associated with significant gains in wellbeing (p ≤.028, d = 0.34), trait mindfulness (p ≤.010, d = 0.47) and self-efficacy (p ≤.028, d = 0.32). This study is therefore the first to demonstrate that the Calm app is associated with positive mental health outcomes. It also shows that regular use is not essential. A thematic analysis of qualitative data supported these quantitative findings. However it also revealed that some participants had negative experiences with the app.

Mindfulness-based self-help apps such as Calm have the potential to both enhance and diminish users' wellbeing. Intermittent mindfulness practice can lead to tangible benefits. Therefore, mindfulness proponents should not recommend daily practice, should increase awareness of the potential for negative outcomes, and resist the idea that mindfulness practice works for everyone. Developers of mindfulness apps ought to make specific features customisable in order to enhance their effectiveness.