Meditation is a technique for resting the mind and attaining a state of consciousness that is different from the waking state [1]. Mindfulness meditation is the process of openly attending, with nonjudgmental awareness, to one’s present moment experience [2]. Over the last 30 years, mindfulness meditation has become increasingly popular in Western society owing to its documented mental and physical health benefits [3]. Mindfulness meditation has been linked to reductions in depressive symptoms, stress, anxiety [4,5], and improved sleep [6], through biopsychosocial mechanisms such as alterations in brain structure, improved attention, increased emotional regulation, and better immune function [4]. Given these benefits, mindfulness meditation has been incorporated routinely in psychotherapy, school-based programs, corporate settings, prisons, and military and is an important part of hospital preventative or disease management programs [3].

Although the evidence for the use of mindfulness meditation is slowly growing, there are multiple barriers to its delivery in traditional group-based formats [7], thus limiting its reach and its potential to be used by individuals seeking to manage mood, stress, or symptoms of a chronic illness. First, participation requires people to travel to a public location with a trained meditation instructor at a specific time of day [5]. This is often not feasible for individuals with diagnoses such as depression, anxiety, or posttraumatic stress for whom attrition rates are as high as 50% [7,8]. Caregivers, parents, and individuals with multiple responsibilities and high stress have busy schedules and may not be able to prioritize lengthy (eg, 60-90 min) weekly classes for extended period [7]. Individuals who live in rural areas or those with chronic disease may find travel to clinics for meditation sessions burdensome [9-11]. To overcome these barriers to participation, we need novel methods to deliver mindfulness meditation.

The aim of this study was 2-fold. First, we reported demographics, clinical characteristics, and usage patterns in a self-selected sample of paying Calm subscribers. Second, we explored the relationship between the self-reported frequency of Calm use and the app’s individual components with self-reported changes in health (mental and physical), stress, and sleep. We hypothesized that subscribers who use Calm more frequently will be more likely to report changes in their health, stress, and sleep.

The Institutional Review Board at Arizona State University (STUDY00009725) approved the study. All participants provided electronic consent before participating in the survey. The datasets generated or analyzed during the study are available from the corresponding author upon request.

This study was cross-sectional. Participants were paying subscribers to the mobile app, Calm (see Multimedia Appendix 1 for screenshots). We used the mobile app, Calm, owing to its popularity. According to a 2015 systematic review of mindfulness apps, there are a total of 700 apps in Apple and Google Play app stores [17]. Calm was the number 1 downloaded health and fitness app between June 2018 and 2019 [18]. In an August 2019 review, CNET (a top website for technology news and editorials) confirmed that Calm was among the most highly rated meditation apps in the Apple and Google Play app stores (all above 4 stars) [19].

Calm guides users through mindfulness meditation. The 7 Days of Calm (ie, introductory course) introduces the user to mindfulness meditation and provides education about beginning a meditation practice. Users receive a new 10-min daily meditation (ie, The Daily Calm) and have access to a variety of meditation content (eg, reducing anxiety and depression, increasing compassion and gratitude) that ranges from 3 to 35 min. Calm offers a variety of meditations for sleep similar to other mindfulness-based apps [20]; however, unlike other apps, Calm offers Sleep Stories. Sleep Stories are narrated fictional stories using traditional storytelling methods, helping to immerse the user in their senses to improve sleep. Other content that Calm offers includes Calm Breathe (breathing training exercises), Calm Music (relaxing, soothing music and nature sounds), Calm Masterclass (monthly series of in-depth audio classes, delivered by experts that teach skills to deal with common stressors and improve well-being), and Calm Body (video lessons on slow, mindful movement routines). Calm also offers a variety of theory-based behavioral strategies to help the user be successful at regular participation including reminders to meditate, ability to track time spent meditating, and opportunities to share progress on social media.

Participants were recruited in April 2019. Calm subscribers were eligible if they were at least 18 years of age, their subscription expiration was at least two months away, they had opened at least two emails from Calm in the last 30 days, and they had completed at least two Calm sessions in the last 30 days.

Subscribers received an email inviting them to answer a series of quantitative and qualitative questions related to their usage of Calm and were informed that their answers would help improve their experience with the app, and results of this study may be used in reports, presentations, or publications. Approximately, 4744 subscribers were contacted on April 9, 54,193 were contacted on April 10, and 41,657 were contacted on April 11. Of the 100,594 subscribers who were contacted, 12,151 (12.08%, 12,151/100,594) participated in the survey. At the end of the survey, participants had the option of providing an email address to be contacted for future studies or to be entered into a draw to win 1 of 2 US $99 Amazon gift cards. No other identifying information was collected, and responses were not linked to in-app usage data.

The survey was developed by 3 doctoral-level researchers/clinicians in the field of behavior change, complementary approaches, and sleep. The survey was Web-based (delivered using Qualtrics) and took most participants between 5 and 10 min to complete (median=6.9; interquartile range=5.7). All responses were anonymous. Participants completed 11 multiple choice quantitative questions (not including demographics) about (1) their engagement with the Calm app (4 questions), (2) why they started using Calm (1 question), (3) clinical characteristics at the time they downloaded the app (2 questions), (4) their connections with other Calm users (3 questions), and (5) whether they noticed changes in their mental health, physical health, stress, or sleep after using Calm (1 yes or no question, separated into 4 subquestions about mental and physical health, stress, and sleep; Textbox 1). Questions varied slightly based on answers to frequency of use (see Multimedia Appendix 2 for all quantitative/multiple choice questions). At the end of the survey, participants completed 4 questions about demographic characteristics. Although the survey included 3 additional open-ended questions, the scope of this paper was limited to discussion of findings from the quantitative data; qualitative analyses will be included in future publications.

Data were analyzed using IBM SPSS 25.0. All variables were categorical, with the exception of age. For questions about health diagnoses, sleep difficulties, reasons for starting Calm, the components of Calm used, and tools used to support engagement, participants were able to endorse multiple items from a list of options; selected options were treated as endorsements (eg, used meditations), and unselected options were treated as nonendorsements (eg, did not use meditations). As not all participants answered every question, sample sizes differed across analyses. Usage frequency was categorized as ordinal, reflecting use of the app or component of the app as nonendorsed, 1 to 2 times per week, 3 to 4 times per week, or 5 or more times per week. Variables for noticing changes in health, stress, and sleep were dichotomous.

Chi-square tests were used to evaluate differences in the use of tools for engagement and frequency of using Calm. To examine the relationships between demographic characteristics and the frequency of using Calm and its components, and we used chi-square tests (sex differences) and binomial logistic regressions (age). Differences in the frequency of using Sleep Stories were further explored using ordinal logistic regressions controlling for sleep difficulties. Chi-square tests were used to analyze differences in the frequency of using Calm and the components of Calm used based on health diagnoses and sleep difficulties. We also used chi-square tests to investigate the relationship between the frequency of using Calm and noticing changes in health, stress, sleep and the relationship between sleep difficulties and noticing changes in health, stress, and sleep. In all cases, significant chi-square tests were followed up with z tests of column proportions. P values were adjusted for multiple comparisons using the Bonferroni correction.

A total of 12,151 subscribers participated in the survey. Sample demographics are presented in Table 1.

More than half (56.86%, 6289/11,061) of respondents had a chronic health diagnosis. Mental health diagnoses (ie, depression, anxiety, or posttraumatic stress disorder; 41.13%, 4549/11,061) were more common than physical health diagnoses (ie, high blood pressure, pain, high cholesterol, asthma, arthritis, cancer, heart disease, emphysema or chronic obstructive pulmonary disease, or other lung disease; 32.19%, 3560/11,061). The most commonly reported mental health diagnosis was anxiety (33.22%, 3675/11,061), and the most common physical health diagnosis was high blood pressure (12.68%, 1402/11,061; Table 2).

Most respondents (76.49%, 8704/11,380) reported sleep difficulties (ie, difficultly falling or staying asleep; Table 3), and 13.90% (1537/11,061) reported insomnia diagnoses (Table 2). Sleep difficulties were significantly more common in females (80.09%, 7009/8751) than in males (61.77%, 1336/2163; χ²₁=355.9; P<.001).

The most common reasons for starting to use Calm were to improve sleep (62.97%, 7475/11,870) and to improve stress (62.11%, 7373/11,870), followed by reducing depression or anxiety (54.47%, 6465/11,870) and improving overall health (40.05%, 4754/11,870; see Multimedia Appendix 3 for less frequently reported reasons).

The aim of this paper was to report demographic characteristics, clinical characteristics, and usage patterns in a self-selected sample of paying subscribers of a consumer-based mobile app (ie, Calm). In addition, we explored the relationship between self-reported frequency of using Calm and its components and noticing changes in health (mental and physical), stress, and sleep disturbance. This is the first paper to report the characteristics of Calm subscribers in addition to the relationship between Calm use and reported changes in health, stress, and sleep.

Respondents were mostly white and mostly female. More than half reported a mental or physical health diagnosis, and approximately three-fourth reported sleep difficulties. The most common reason for starting to use Calm was for sleep, followed by stress and depression. Most respondents used Calm 5 or more times per week.

Meditations and Sleep Stories were the most commonly used components. It is not surprising that meditation was the most frequently used Calm component as Americans are more consistently including meditation as part of their lifestyle [21]. Meditation is the fifth most common type of complementary approach to health practiced by adults [22]. In addition, Calm was originally marketed as a mindfulness meditation app, and after many iterations and changes to the app over time, it now offers added components such as Sleep Stories.

Even though our sample was mostly women, men were slightly more likely to use meditation. Historically, women report higher use of meditation when compared with men. In a 2019 analysis of 2012 data from the National Health Interview Survey [21], 5.7 million men reported using meditation as compared with 12.2 million women. Both men and women reported meditation being helpful to reduce stress. In future studies, it would be interesting to know why men use the meditations more than the many other components of the app. This information may impact the way in which consumer-based meditation apps consider marketing content based on gender. For example, advertising Calm with pictures of men meditating may help to encourage men to subscribe to the app.

Women were more likely than men to use the Sleep Stories. This may be partially attributed to women reporting higher levels of sleep difficulties. It is well known that women have a higher frequency of sleep disturbance as compared with men owing to hormonal changes over the life span [23]. Sleep meditations may represent a manageable, nonpharmacological strategy for women (and men) to improve sleep. However, further analyses suggest that sleep difficulties do not fully account for women’s more frequent use of Sleep Stories. Future research using surveys and qualitative data from consumers (both men and women) about what they specifically enjoy about the Sleep Stories would be useful information for future content development, consumer engagement, and clinical trials.

Tracking and reminders were the most common in-app tools used to support engagement, and using the app at bedtime (using Calm at bedtime) appeared to be the most effective adherence strategy to maintain engagement with the app over time. Research on the efficacy of mobile apps in impacting behavior shows that tracking behavior and feedback are among the most successful strategies for behavior change [24]. Tracking is also one of the most popular technology strategies used by mobile apps for health and wellness [25]. Almost 40% of our sample reported using tracking as a tool to help them continue to engage in using Calm. Currently, Calm tracks how many sessions and minutes the user has participated in over time. Recent evidence suggests that tracking plus feedback may be more impactful for improvements in behavior change as compared with tracking alone [26-28]. For example, in a randomized clinical trial testing the effects of an automated tracking-texting intervention on physical activity (mActive), coupling text messages containing automated personalized feedback with physical activity tracking led to twice as many participants achieving their daily step goal as compared with other groups [26]. Providing the subscriber feedback, based on the use of the app, could thus be an effective strategy for consumer-based mindfulness meditation apps to keep subscribers engaged once they sign up as a paying member. In addition, finding other ways to track and provide feedback outside of sessions and minutes of meditation could provide more value to a meditation app. For example, the users’ perception of their stress, mindfulness, or happiness after a session could be tracked in conjunction with patterns of use. Providing this information as feedback would allow users to observe the relationship between using Calm and changes in their moods, thoughts, and behaviors. Future research in this area is warranted.

When we asked those who engaged in the app more often (more than 3 times per week) precisely how they stay engaged, many reported that using Calm at bedtime (eg, Sleep Stories, Daily Calm, and other sleep meditations) contributed to adherence. It is well known that there are barriers to beginning and maintaining health behaviors (eg, physical activity, diet, and meditation) [29]. However, using Calm (and other mindfulness-based apps) at bedtime/for sleep may have fewer barriers (eg, time and motivation) than participating in another health behavior. For example, Calm Sleep Stories require the user to begin the Sleep Story by lying in bed and assuming a comfortable position with the goal of helping the user to fall asleep. This does not require added time or motivation (beyond starting the Sleep Story) and may be an easier task, thus users reported using Calm at bedtime/for sleep as a way of using the app more consistently.

An interesting finding from our survey was that almost half of our sample had friends or family that used Calm, and many talked with their friends or family about Calm. However, overall, respondents reported not wanting to be connected with other Calm users. When exploring mental or physical health diagnoses and the relationship to reporting the desire to be connected to other Calm users, those with mental health diagnoses wanted to connect with other Calm users. Recent research suggests that individuals with mental health problems are increasingly turning to online communities for social support [30,31]. Although more than half of the survey sample started using Calm for mental health reasons (ie, anxiety and depression), and almost half reported a mental health diagnoses (ie, anxiety, depression, and posttraumatic stress); only 3% used the Calm Facebook community to maintain app engagement. This is surprising given the strong presence of Calm on Facebook and other social media platforms. It may be that this convenience sample of highly engaged users already felt well connected in terms of social support, and thus, their feedback on additional support might not be generalizable. It is also possible that concerns related to privacy and stigma deter users with mental health diagnoses from disclosing personal or emotional information to a larger community [32]. These individuals may prefer to connect specifically with other users who share common difficulties [33,34]. Future investigation is necessary to determine what the best way is to connect users and to facilitate social support for subscribers of these apps.

Participants using Calm more frequently were incrementally more likely to notice changes in both mental and physical health, stress, and sleep, as were those who reported using Calm for a longer duration. This is not surprising. Participants are likely becoming more mindful and reap the benefits associated with mindfulness [35,36]. Present literature on the amount of meditation practice needed to observe changes in a range of health outcomes is varied and limited [37]. However, there is promising evidence for greater effects on health, stress, and sleep as time spent (eg duration, frequency) increases [37,38]. This information is important because regardless of the component (ie, general use of Calm, specifically meditation, and specifically Sleep Stories), participants who used the app more frequently clearly noticed changes in their health. It is well known that individuals are more likely to participate in a behavior if they enjoy it or if they believe it benefits them [39,40]. However, it is important to note that survey questions about changes in all aspects of health were nondirectional, and respondents’ reports of noticing changes were interpreted with the assumption that changes reflect improvements. In addition, future research should explore the correlation between self-reported noticing changes and directional changes on validated outcome measures. It is possible that, retrospectively, users believe that there have been changes, but when completing a fully validated measure, scores remain the same over time. The relationship between actual and perceived outcomes and time spent (duration in minutes and length of membership) using the app would also be worth exploring in future research. Future research should also explore the optimal dose of mindfulness meditation on a mobile app to improve health outcomes. For example, it is possible that total time spent using a meditation app is less important than frequency of use it (eg, 10 min a day for 3 days could be better than 50 min in 1 day).

Respondents who used the Sleep Stories more frequently were more likely to report noticing changes in their sleep and physical health. Consumer sleep technologies have become quite popular to help individuals improve or self-monitor their sleep [20]. In a review by Ko in 2015 on consumer sleep technologies, a number of the top-rated sleep apps helped users track their sleep trends (movements that represent presence or absence of sleep), recorded ambient sounds (sleep talking and snoring), alerted users when to go to bed, and tracked their sleep habits over time. Although some of the apps were developed to facilitate sleep onset using visual graphics, relaxing music, and nature sounds, none incorporated Sleep Stories. Uniquely, Calm has Sleep Stories, similar to meditation, that help the user to practice moment-to-moment awareness, experience greater attentional control, and decrease ruminating thoughts, which may lead to less anxiety about sleeplessness [41,42]. The stories bring listeners focus into the present moment, helping them to disengage with negative thoughts/beliefs about sleeplessness, and provide cognitive distraction, which may lower presleep anxiety or arousal and help users sleep better.

It is important to note that those who used the Sleep Stories more frequently reported noticing changes in their sleep and physical health only, whereas those using meditations more frequently noticed changes in their mental and physical health, as well as stress. Although there is a large body of research demonstrating the relationship between sleep and physical health [43], many studies observe similar or stronger relationships between sleep and mental health [44,45]. Given this, it is surprising that using Sleep Stories was not associated with changes in mental health or stress. There may be more varying long-term benefits of using Calm for meditation as compared with sleep. Little research has been conducted to determine the effects of sleep components of mindfulness-based apps, and no studies have specifically assessed the effects of Calm Sleep Stories in improving sleep and health outcomes. Considering the increases in sleep components to mindfulness meditation apps, future research on the extent to which these components impact sleep is warranted.

There were a number of limitations, inherent in descriptive, survey-based studies. First, although this was a convenience sample of Calm users that opened an email from Calm and decided to complete the survey, engagement was still varied (60.03% of respondents used the app 5 or more times per week, 27.45% used 3-4 times per week, and 12.52% used only once or twice weekly), and there may be a viable sample of individuals who vary in their use of Calm. In addition, individuals who use Calm more frequently may have more favorable opinions of the app and have benefitted more from using it. Those who do not find Calm beneficial may have elected not to participate. In addition, the survey did not include the option to endorse using Calm less often than 1 to 2 times per week, which may have decreased participation rates of infrequent users. Finally, our sample is mostly white, female, and with higher income. Future studies should use stratified recruitment strategies to engage a more diverse sample in terms of age, gender, income, race/ethnicity, and pattern of usage. Second, as this was a cross-sectional, nonexperimental study, we cannot infer causality with regard to the impact of Calm; rather, analyses rely on subscribers’ recollections of app usage, perceptions of changes over time, and their beliefs about how Calm has impacted them. Future studies should explore these relationships prospectively, and randomized clinical trials are needed to determine extent to which changes can be attributed to Calm usage. Third, the survey items were designed specifically for this study, and thus, there is no previous research on their validity. In addition, questions asking participants to notice changes in their health, stress, and sleep after using Calm were dichotomous (yes/no), and results were interpreted with the assumption that changes reflect improvements. Future studies should extend the findings of this report by using validated questionnaires to assess directional changes in mental health, physical health, stress, and sleep outcomes. Finally, as many respondents used both meditations and Sleep Stories, it is difficult to disentangle the unique effects of those components. Future dismantling studies could randomize participants to only use 1 component of the app and look at the benefits of each component on its own. In addition, future surveys should collect more detailed information regarding the specific aspects of meditations and Sleep Stories that users enjoy, and this information should be presented alongside qualitative data, as such data could inform future experimental studies.

This is the first study to report the demographic and clinical characteristics and patterns of usage among a large sample of paid subscribers to a top-rated health and fitness app, Calm. Results showed that most subscribers used meditation and Sleep Stories at least three to four times per week, and more frequent use was associated with perceived changes in their physical and mental health, stress, and sleep. We have also identified the most popular tools within the app preferred by subscribers. This paper provides information for Calm and other mindfulness-based apps about strategies to tailor content and features (eg, emphasize benefits for sleep, provide tracking with feedback, and incorporate social support that is private/anonymous) and potentially increase subscribers and retention rates. From a scientific perspective, these strategies can help participants engage in studies and facilitate feasibility. This study sets the stage for future clinical trials aimed at determining the efficacy of Calm in improving physical and mental health, stress, and sleep.