Non-pharmacological Interventions to Improve Stress and Sleep Among College Students
Phase: NA
Conditions: Stress, Psychological, Sleep, Transcutaneous Electric Nerve Stimulation, Vagus Nerve Stimulation, Mindfulness
Sponsor: University of Florida

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Non-pharmacological Interventions to Improve Stress and Sleep Among College Students 
NCT05218109  
3/3/22 
 
 

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1. Project title 
Non-pharmacological interventions to improve stress and sleep among college students 
2. Investigators 
Sarah Bottari (co- PI)  
Liva LaMontagne (co-PI) 
John Williamson (co-I; mentor of student PI) 
David Diehl (co-I; mentor of student PI)  
Jennifer Doty (co-I; mentor of student PI) 
3. Abstract 
Chronic poor sleep is prevalent among college students and has wide-ranging negative 
consequences, including poorer academic performance, increased health risk behaviors, and 
greater risk for mental health problems. Despite this fact, estimates suggest that 80-90% of students 
with chronically poor sleep are not receiving help from their college or university. Likewise, college 
student mental health, which shares a bidirectional relationship with sleep quality, has become a 
significant and growing public health concern. Estimates suggest that roughly one third of college 
students meet criteria for a clinically significant mental health problem, and rates of depression, 
anxiety, and suicidality are rising. Digital mental health programs, delivered via mobile app, present 
one promising approach to address this need and expand treatment accessibility. In particular, 
mindfulness mobile apps have achieved both mental health and sleep benefits across several 
randomized controlled trials in student populations; however, adherence and sustained use after 
interventions have been low. Thus, it is important to address barriers to sustained mindfulness 
practice in order to optimize user outcomes.  
The current study explores using tVNS as a potential method to alleviate barriers to establishing a 
habit of mindfulness practice. In mindfulness interventions it is not uncommon for participants to 
report an initial escalation of anxiety and distress as they directly engage with negative thoughts. 
While accepting, decentering, and deriving meaning from these negative reactions is an important 
feature of the psychotherapeutic process in mindfulness interventions, they can also lead to 
disengagement or drop out from the intervention. Similarly, difficulty learning the skill of meditation is 
also common and can contribute to participant dropout. tVNS may exert an anxiolytic effect through 
effects on limbic structures and activation of the parasympathetic nervous system. Moreover, tVNS 
increases positive affect (i.e. calm) and has been linked to improved interoceptive awareness, which 
are two other potential psychological mediators of mindfulness interventions. Thus, these two 
separate treatment approaches appear complementary, yet there are no published trials using them 
in combination. The proposed study will enable us to evaluate the utility of this combined 
treatment approach in enhancing college student sleep and mental health, with potentially 
broader impacts for clinical populations.  
4. Background 
Insufficient sleep in the United States has recently been recognized as a public health epidemic.1 
College students are at increased risk of experiencing poor sleep due to a “perfect storm” of 
challenging biological, social, and environmental factors, including delayed circadian rhythm, early 
class times, residential sleep environments, high stress levels, increased social demands, and 
greater substance and electronic use.2–4 Chronic poor sleep is prevalent among college students; 

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more than one third have identified sleep difficulties as “traumatic or very difficult to handle.”5 Despite 
the prevalence and increasingly well-known negative consequences of poor sleep,2,6 sleep health 
has not historically been prioritized as an area for intervention on college campuses. For instance, 
according to the 2018 Center for Collegiate Mental Health annual report, approximately 11,000 
students reported sleep disturbances on intake, yet less than one percent had that concern 
prioritized by clinicians.7 Moreover, when sleep questions were included as part of a universal 
behavioral health screening survey, more than 10% of students requested support for their sleep 
concerns.8 Thus, there is a clear unmet need for sleep intervention among college students. 
Importantly, sleep and mental health share a bidirectional relationship, and the prevalence of sleep 
problems on college campuses parallels the high rates of anxiety and depressive symptoms.9 In 
large national studies, approximately 41% of United States college students report moderate to 
severe depressive symptoms and 34% report moderate to severe anxiety symptoms.10 These 
mental health problems are associated with a variety of negative outcomes, including greater 
substance use, poorer academic performance, increased self-harm behaviors, and suicidal ideation 
and attempts.11 While counseling centers can be found on most college campuses, the increased 
demand for mental health services has unfortunately not been met with a proportional increase in 
counseling center staff and funding. As a result, many counseling centers are under-resourced and 
operate at full capacity with waitlists for much of the year.12 On a nation-wide survey of college 
counseling center directors, 90% raised concerns that students may not be receiving treatment when 
it is most needed.13 As a result, there is growing interest in digital mental health interventions, such 
as mindfulness apps, to expand treatment accessibility and improve student well-being and sleep 
quality.14–16  
Though digital mindfulness interventions offer many potential sleep and mental health benefits for 
college students, rates of adherence and sustained use of mindfulness apps have been low.17,18 
Thus, more research needs to examine facilitators to the uptake and sustainability of mindfulness 
practice, as well as complementary treatment methods that can boost the perceived effectiveness of 
mindfulness practice. The current study explores tVNS as one such complementary treatment. tVNS 
is a safe, non-invasive form of vagus nerve stimulation (FDA-approved for the treatment 
resistant depression and epilepsy). tVNS targets the auricular branch of the vagus nerve 
through stimulation at sites of the external ear, such as the inner tragus.19 It has been shown to 
affect vagally mediated components of the limbic system that are critical to sleep and mood via 
activation of the nucleus of the solitary tract (NTS).20,21 Moreover, tVNS has been shown to 
increase parasympathetic tone,22 which can have a beneficial effect on both sleep and 
mood.23,24 Stimulation of the vagus nerve has been associated with reductions in daytime 
sleepiness,25 decreased sleep latency,26 greater slow wave sleep,26,27, and longitudinal 
improvements in self-reported sleep quality28–30 in clinical and preclinical studies. tVNS has also 
been associated with improvements in anxiety and depressive symptoms.30–32 Thus, tVNS may 
be a convenient means to improve sleep and mental health outcomes among college students 
engaging in mindfulness practice, although this potential has not yet been empirically tested. 
The current study will evaluate the feasibility, acceptability, and efficacy of this novel combined 
treatment approach relative to mindfulness-only and control conditions.  
5. Specific Aims 
The goal of the proposed research project is to explore the acceptability and efficacy of a combined 
transcutaneous vagus nerve simulation (tVNS) and mindfulness intervention in enhancing sleep and 
well-being among college students and compare it to mindfulness-only and control conditions with 
the hypothesis that the combined intervention will have greater efficacy due to synergistic brain 
effects of tVNS and mindfulness. In addition to experimental results, the proposed project will 

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generate effect size data to inform future trials of the combined approach and assess the feasibility 
and acceptability of our study design.  
Specific Aim 1: To evaluate the feasibility and acceptability of sustained engagement with the 
Brightmind mindfulness app among college students. 
Research question 1.1: Do students find this app acceptable and engage with it consistently 
across a 4-week period?  
Research question 1.2: What are the barriers and facilitators to sustained engagement with 
the app? 
Hypothesis 1.3: Participants who spend more time engaging with the app will see greater 
improvements in mental health (e.g., stress, anxiety, depressive symptoms, positive affect) 
and HRV compared to participants who spend less time engaging with the app. 
Specific Aim 2: To obtain preliminary effect size data on the efficacy of the Brightmind mindfulness 
app in improving proximal and distal mental health outcomes among college students  
Hypothesis 2.1: Participants in the mindfulness-only group will demonstrate greater 
improvements in mental health (e.g., stress, anxiety, depressive symptoms, positive affect) 
than participants in the control group 
Hypothesis 2.2: Overnight heart rate variability (HRV), positive affect, and interoceptive 
awareness will be greater in the mindfulness-only group compared to the control group. 
Hypothesis 2.3: HRV will increase from before to after each mindfulness session. 
 
Specific Aim 3: Determine feasibility and acceptability of the combined tVNS + mindfulness 
intervention.  
Research question 3.1: Do students find this combined intervention acceptable and 
demonstrate adequate adherence (i.e. use tVNS or sham + mindfulness for at least 10 
minutes/day at least 4 days/week for 2 weeks)?  
Research question 3.2: What are the barriers and facilitators to adherence with the combined 
intervention? 
Hypothesis 3.3: The combined intervention will be well-tolerated and receive positive 
acceptability ratings. 
Specific Aim 4: Develop effect size data on the efficacy of the combined tVNS + mindfulness 
intervention in improving sleep and mental health among college students. 
Hypothesis 4.1: Participants in the tVNS + mindfulness group will demonstrate greater 
improvements in sleep quality and quantity than participants in the sham + mindfulness 
group or control groups.  
Hypothesis 4.2: Participants in the tVNS + mindfulness group will demonstrate greater 
improvements in mood and mood related factors ( e.g., stress, anxiety, depressive 
symptoms, positive affect) than participants in the sham + mindfulness group or control 
groups.  
6. Research Plan 

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6.1 Study timetable and logistics. The study will consist of an intake-training session and a 4-week 
intervention phase. Participants will complete brief weekly online surveys during the intervention 
phase and a follow-up online survey 4-weeks after the end of the intervention period. Face-to-face 
interaction with subjects will take place at the University of Florida McKnight Brain Institute (MBI) 
during the intake-training visit, the return of study equipment, and the distribution of participant 
payment 
 
 
 
Figure 1 Visualization of the study protocol and timeline. 
6.2 Experimental design. As participants are scheduled for intake visits, they will be assigned to 
either a tVNS group (tVNS + mindfulness or sham + mindfulness) or a non-tVNS group (mindfulness 
only or control) by the research coordinator based on practical considerations (i.e. tVNS device 
availability) to expedite study completion. Within each of these groups, participants will be 
randomized via alternating order to either the active or control condition (in other words, once a 
participant is assigned to a tVNS group, they will then be randomized to either the tVNS + 
mindfulness or sham + mindfulness group). This process will repeat until each group has the target 
number of participants.  
In the initial visit, a research assistant will review the appropriate informed consent form. During this 
process, participants assigned to a stimulation group (tVNS + mindfulness or sham + mindfulness) 
will be told that they have been randomized to receive one of two different types of noninvasive 
vagal nerve stimulation, that we think one of the conditions may be more effective, and that they 
have a 50/50 chance of being in that group. For participants randomized to the non-stimulation 
groups (mindfulness only or control), they will be told that they have been randomly assigned to use 
one of two mobile app interventions, that we think one of the interventions may be more effective, 
and that they have a 50/50 chance of being in that group. After providing written informed consent, 
participants will complete a brief health questionnaire as part of our inclusion/exclusion screening 
(see section 6.5). If participants screen out after signing the informed consent, the session will end, 
and any data collected will be kept in a locked filing cabinet. 
After passing the screening, participants will complete an online survey that will include measures of 
mood, well-being, pain, daytime sleepiness, and sleep quality (see section 6.6 for specific 
measures).  
These measures are self-report and will establish a baseline for each participant. They will be 
provided with and trained on the following equipment depending on their group assignment:  
- 
Brightmind Meditation mobile mindfulness app (Brightmind Meditation, LLC; 
https://www.brightmind.com): Participants in each of the three active treatment groups (tVNS 
+ mindfulness, sham + mindfulness, and mindfulness-only) will be provided with free access 
to the Brightmind mobile mindfulness app. During the intake session, they will download the 
app and complete an orientation to learn its features. They will be asked to practice 
mindfulness meditation through the app for 10 minutes each evening during the 4-week 
Intake-
Training Visit 
• Week 0
• Baseline Survey
Intervention Phase
• Weeks 1-4
• Weekly Surveys
Follow-up
• Week 8
• Follow-up Survey

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intervention phase, with compliance defined as using the app 10 minutes/day for at least 4 
days/week.  
- 
Control task: Participants in the control group will be provided with the link and instructions 
for a control task (an online number puzzle: https://play2048.co/) that has been used in 
previous studies of mindfulness apps.33 They will be asked to engage with this control task 
for 10 minutes each evening during the 4-week intervention phase, with compliance defined 
as engaging with the task 10 minutes/day for at least 4 days/week. Participants in the control 
group will receive free access to the Brightmind mindfulness app after study completion. 
- 
Soterix Medical RELIfit-Tragus Device (Soterix Medical Inc.; 
https://soterixmedical.com/research/tavns): Participants in the tVNS + mindfulness and sham 
+ mindfulness groups will be provided with the Soterix Medical RELIfit-Tragus device, as well 
as its accompanying equipment (e.g., device charger, gel, cleaning materials). During the 
intake session, they will be trained on procedures for using the device, including gel 
application, electrode placement, and device configuration. Once the research assistant 
confirms that the participant understands how to apply the electrodes and set the stimulator, 
the research assistant will demonstrate how to take a picture of the electrode application to 
check the quality of the application. Participants will be instructed to take a picture that hides 
the identifying features of the face. Participants will be asked to administer tVNS concurrently 
with mindfulness practice for at least 4 days per week for the first 2 weeks of the intervention 
phase. They will be asked to send a picture of the application of the electrodes for each 
stimulation session. If a picture of the application indicates improper placement, a research 
assistant will contact the participant via phone or email to review proper form. 
- 
Fitbit Wristband (Fitbit LLC): All participants will be provided with a Fitbit wristband for 
overnight sleep and HRV measurement. They will be instructed on the best method for 
wearing the band during the initial visit. Participants will be asked to wear the wristband 
overnight each night for the 4-week intervention phase, with compliance defined as wearing 
the device overnight at least 4 nights/week.  
- 
Polar H10 Chest Strap (Polar Electro; https://www.polar.com/us-
en/products/accessories/h10_heart_rate_sensor): All participants will be provided with a 
Polar H10 chest strap for HRV measurement during mindfulness practice. They will be 
instructed on the best method for wearing the chest strap during the initial visit. In addition, 
the research assistant will assist them in downloading a mobile app for data 
collection/storage and pairing it with the Polar H10 band for HRV recording. They will be 
asked to wear the chest strap during at least one mindfulness practice session per week 
during the 4-week intervention period.  
After receiving study equipment and completing training procedures, participants will begin the 
intervention phase at home. They will be provided with written and/or video instructions as a 
reminder of procedures for the intervention phase depending on their group (summarized in Table 
1). Study staff will also be available to answer questions or provide reminders via email and/or 
phone. During the intervention phase, participants will complete brief weekly online surveys 
consisting of some of the measures administered at baseline (see section 6.6). The survey will be 
sent via an electronic link to participants’ email address or phone number. At the completion of the 4-
week intervention phase, the research assistant will coordinate with the participant to schedule a 
time to return study equipment and distribute participant payment. Participants will be compensated 
for their time and effort (see section 10). 
 Group 
Intervention Phase Procedures 

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tVNS + mindfulness (n = 20) 
- 
Practice mindfulness meditation through the 
Brightmind Meditation app for 10 minutes each 
evening for 4 weeks  
- 
Administer tVNS concurrently with mindfulness 
practice at least 4 days per week during the first 2 
weeks of the intervention phase  
- 
Wear the Polar H10 chest strap during mindfulness 
practice at least 1x/week 
- 
Wear the Fitbit overnight for 4 weeks 
Sham + mindfulness (n = 20) 
- 
Practice mindfulness meditation through the 
Brightmind Meditation app for 10 minutes each 
evening for 4 weeks  
- 
Administer sham stimulation concurrently with 
mindfulness practice at least 4 days per week during 
the first 2 weeks of the intervention phase  
- 
Wear the Polar H10 chest strap during mindfulness 
practice at least 1x/week 
- 
Wear the Fitbit overnight for 4 weeks 
Mindfulness only (n = 20) 
- 
Practice mindfulness meditation through the 
Brightmind Meditation app for 10 minutes each 
evening for 4 weeks  
- 
Wear the Polar H10 chest strap during mindfulness 
practice at least 1x/week 
- 
Wear the Fitbit overnight for 4 weeks 
Control (n = 20) 
- 
Engage with the control task for 10 minutes each 
evening for 4 weeks  
- 
Wear the Polar H10 chest strap during the control task 
at least 1x/week  
- 
Wear the Fitbit overnight for 4 weeks 
Table 1. Intervention phase procedures for each experimental group.  
6.3 Subjects. This study utilizes a between-participant design and will recruit 80 healthy college 
students aged 18 – 30. Pregnant women may not participate in this study—pregnancy tests provided 
by the study will be used for women of child-bearing age randomized to a tVNS group prior to starting 
the study and after the consenting process. Pregnancy tests will only be given in the intake session. 
 
6.4 Recruitment and Retention. We will recruit a volunteer sample of undergraduate students from 
the Gainesville, Florida community who are interested in managing stress. We will post IRB-approved 
flyers around the community and on the UF campus. The flyers include a survey link where interested 
students can provide their contact information if they believe they qualify for the study to allow study 
staff to contact them to schedule an intake appointment. The investigators will be involved in 
recruitment of participants from multiple sources, including campus tabling events, posting flyers on 
UF campus and through GatorWell, emails to relevant listservs, making announcements during 
undergraduate classes, and through word of mouth. The investigators will also post announcements 
to Facebook and Twitter (see Social Media Strategy). Subjects will be expected to provide their own 
means of transportation. 
 
6.5 Inclusion/Exclusion Criteria. Participants will include adults between the ages of 18-30, 
consistent with the typical college population. Participants must own a smartphone, be able to read 
and write English, and not be in ongoing psychotherapy. 
 

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Major medical illnesses including diagnosed severe neurological illnesses (e.g., stroke, seizure 
history), medical conditions associated with neurological effects (e.g. heart, kidney disease), 
autoimmune disorders, and severe psychiatric diseases (e.g., schizophrenia) will be excluded. 
Participants with any history of brain surgery, tumor, intracranial metal implantation, pacemakers or 
other implanted devices will be excluded. These elements will be assessed via self-report.  
 
Sleep medications and/or psychotropic medications are exclusionary. Current illicit or prescription 
drug abuse (within the last two months) will result in exclusion or delay. Marijuana or alcohol 
abuse >2 weeks out will be acceptable for inclusion. Participants who are pregnant will be excluded. 
If participants have a history of adverse reaction to electrical nerve stimulation, they will be excluded. 
 
6.6 Measures  
 
General Questionnaire. This questionnaire will include basic demographic and health questions that 
will be self-reported by the subjects. This may include questions about their medical history, psychiatric 
history, substance use history, and current medications. Since our study requires a return visit, this 
questionnaire may also include participant contact information.  
 
Behavioral. The following tests may be included in the online surveys: 
 
 
Pittsburg Sleep Quality Index (PSQI):34 This 19-item scale yields component scores for seven 
different domains of sleep quality: subjective sleep quality, sleep latency, sleep duration, 
habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime 
dysfunction. We will use this measure to assess for changes in self-reported sleep quality 
across the study period. This measure may be administered at intake, week 2, week 4, and 
follow-up.  
 
Epworth Sleepiness Scale (ESS):35 This 8-item questionnaire assesses daytime sleepiness 
by having participants rate their usual chances of dozing off while engaged in common 
activities. We will use this measure to assess for changes in self-reported daytime sleepiness 
across the study period. This measure may be administered at intake, week 2, week 4, and 
follow-up. 
 
Patient Health Questionnaire-8 (PHQ-8):36 This 8-item questionnaire assesses depressive 
symptoms, and we will use it as a mental health outcome measure. We will adjust the time 
scale to asking about symptoms over the past week. This measure may be administered at 
intake, week 2, week 4, and follow-up.   
 
Generalized Anxiety Disorder-7 (GAD-7):37 This 7-item questionnaire screens for symptoms 
of generalized anxiety disorder and characterizes their severity, and we will use it as a mental 
health outcome measure. We will adjust the time scale to asking about symptoms over the 
past week. This measure may be administered at intake, week 2, week 4, and follow-up.   
 
Perceived Stress Scale (PSS):38 This 10-item questionnaire measures the degree to which 
situations in one’s life are appraised as stressful. In particular, it gauges how unpredictable, 
uncontrollable, and overloaded respondents find their lives. We will adjust the time scale to 
asking about symptoms over the past week and use this measure to track potential changes 
in stress levels.  This measure may be administered at intake, weekly, and at follow-up. 
 
Positive and Negative Affect Schedule (PANAS):39 Positive emotions (overall, serenity, 
joviality, self-assurance) and negative emotions (overall, sadness, fear, hostility) will be 

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measured with 17 adjectives each. This measure will be used to assess changes in self-
reported emotions. This measure may be administered at intake, weekly, and at follow-up. 
 
Multidimensional Assessment of Interoceptive Awareness-2 (MAIA-2):40 Interoceptive 
awareness will be assessed as a potential proximal outcome of mindfulness practice. We will 
use the body listening (3 items), trusting (3 items), and self-regulation (4 items) subscales (10 
items total). These subscales may be administered at intake, weekly, and at follow-up. 
Applied Mindfulness Process Scale (AMPS):41 The AMPS scale measures mindful emotion 
regulation – decentering, positive emotion regulation, and negative emotion regulation. This 
measure will be used to assess for changes in mindful emotion regulation associated with 
longitudinal use of the mindfulness app. The 15-item scale may be administered at intake, 
week 2, week 4, and follow-up. 
The Nondual Awareness Dimensional Assessment - State (NADA-S).42This 3-item scale 
measures mindfulness-related processes of self-transcendence. We use it to assess 
changes in self-transcendence associated with the use of the mindfulness app. The scale is 
administered at intake, weekly, and at follow-up. 
PERMA Profiler:43 This questionnaire measures flourishing across 5 domains: positive 
emotion, engagement, relationships, meaning, and accomplishment following Dr. Seligman’s 
well-being theory. We will use this 19-item measure to assess for changes in self-reported 
well-being. This measure may be administered at intake, week 4, and at follow-up. 
 
Pain Numeric Rating Scale: Participants will be asked to rate their current pain level on a scale 
from 0-10 (0 = no pain at all, 10 = highest level of pain imaginable), as tVNS and mindfulness 
may provide pain relief. This measure may be administered at intake, weekly, and at follow-
up. 
 
System Usability Survey (SUS):44 This is a standard version of a usability scale. Participants 
will be given 10 statements regarding the usability of the equipment they used, and they will 
report how much they agree with each statement on a 1 – 5 scale. This measure will only be 
given after the completion of the intervention phase (week 4).  
 
Acceptability of Intervention Measure (AIM), Intervention Appropriateness Measure (IAM), and 
Feasibility of Intervention Measure (FIM):45 These brief 4-item scales measures the degree to 
which participants believe an intervention is acceptable, appropriate, and feasible. These 
measures will only be given after the completion of the intervention phase (week 4). 
 
Physiological. Subjects will be given a Fitbit brand wristband that offers real-time physiological data 
acquisition to use to monitor their sleep quantity, quality, and overnight heart rate variability (HRV) 
during the intervention phase. Participants will also be given a Polar H10 chest strap to use during 
mindfulness sessions, measuring their momentary HRV. Participants may be provided a preassigned 
account and password for these wearable devices, which may be accessed by the research team to 
manage raw data.  
 
Analysis Plan.  
- 
To analyze feasibility data, we will qualitatively examine rates of recruitment and drop 
out/attrition and compare them to prior research. Quantitatively, to examine whether dropout 
is selective, participants who completed the study will be compared to participants who 
dropped out on group via chi-square independence test. To analyze acceptability data, 
outcomes regarding tolerance and acceptability will be compared between the groups via 

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ANOVA. In addition, we will perform thematic analysis of participant responses to open-ended 
questions about feasibility and acceptability.  
- 
To examine trajectory of sleep and mental health/well-being over time, multilevel modeling 
(MLM) analyses will be conducted using unrestricted full information maximum likelihood in R 
via the “lme4” package. Separate models will be conducted using each sleep and mental 
health/well-being outcome measure as a dependent variable. Linear and quadratic time trends 
will be estimated, and intervention group will be included as a moderator. To examine 
adherence, the number of minutes participants spend engaged with the app or tVNS device 
per week will be averaged. Then, an MLM will be conducted using average weekly 
engagement as the dependent variable and time (linear and quadratic) and group as 
predictors. Retention rates between intervention groups will be compared using an 
independent samples t-test. 
 
Nerve Stimulation. The auricular branch of the vagus nerve projects to the brainstem and is 
accessible via electrical stimulation through surface electrodes. Stimulation produces vagus sensory 
evoked potentials not induced with off-target stimulation.20,21 
Earpiece Placement: All subjects will be instructed to place the Soterix device earpiece on 
their left ear such that the stimulation electrode is positioned over the inner tragus and the 
return electrode is positioned just anterior to the tragus to minimize off-target stimulation per 
local pilot protocol (see Figure 2). Subjects will demonstrate their ability to set up the 
stimulator—including earpiece placement—and text the picture of the electrode placement 
with their faces occluded, similar to Figure 2. Research assistants will also provide a link with 
an instructional video that participants can refer to in order to ensure they have properly placed 
their electrodes. Participants will be asked to send a photo of their electrode placement for 
each stimulation session via SMS. 
Stimulation Device: We will use the Soterix Medical RELIfit-Tragus transcutaneous electrical 
nerve stimulation devices. For details, see “Device type” in my.irb. Stimulus pulses will be 
alternating in polarity to reduce tissue irritation and will be delivered at 20Hz, 200 μs pulse 
width, within the range of published stimulus parameters.46–48  
Calibration: Participants will undergo calibration during the intake-training visit. Prior to 
calibration, participants will be informed that the stimulation intensity will be slowly increased 
until they report any discomfort and then reduced to a comfortable level for the remainder of 
the study. Individual sensitivity to tVNS stimulation will then be evaluated with a structured 
stepped-ramp protocol, with a brief pause at each step during which the participant will be 
asked what the stimulus felt like to them and if they experienced any discomfort. The 
stimulation intensity will then set to 80% of the discomfort threshold for the active tVNS group 
and near to 0% (just enough to keep device on) of the discomfort threshold for the sham 
stimulation group. If the participant reports irritation with stimulation during this ramp up 
procedure (which can last ~15 minutes), electrode adhesion will be checked (if there is poor 
contact, it can affect the sensation) and stimulation intensity will be reduced if necessary (any 
change will be documented). If the participant further indicates discomfort, stimulation will be 
discontinued. If the patient evidence dizziness/lightheadedness or if a comfortable level of 
stimulation is not achievable at calibration, the participant will be removed from the study (this 
will be documented).  
Blinding: Participants will be blinded to condition and told that, after calibration, the stimulus 
intensity will be set to below the calibration (discomfort threshold) level and that they may not 
feel the stimulation once reduced. We have used this form of psychological sham approach in 

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the past.22 Participants will be provided with a maximum of 14 blinding codes that correspond 
with the appropriate stimulation parameters and intensity depending on their group 
assignment. These blinding codes must be entered into the tVNS device in order for 
stimulation to be administered. They are one-time use only, meaning that participants will not 
be able to administer tVNS more frequently than instructed in the study protocol. Moreover, 
participants 
will 
be 
told 
that 
these 
blinding 
codes 
correspond 
to 
stimulation 
parameters/intensity that is calibrated to them only, and that they are not safe to be used on 
other people (e.g., friends, roommates). The picture of earpiece placement that participants 
send with each stimulation session should act as a further control against participants allowing 
others to use the stimulation device. The blinding codes will also specify stimulation length, 
with a maximum of one hour (after which, stimulation will be turned off). Of note, stimulation 
also turns off if there is not good connectivity between the earpiece and the tragus (e.g., if the 
earpiece falls off or if it is placed on another part of the body without adequate connectivity).  
At-Home Device Use: Per the Soterix website: “The Soterix Medical taVNS device is intended 
for use by, or under the direct or remote supervision of, a trained healthcare practitioner.” We 
have discussed this statement via email with Abhishek Datta, CEO and CTO of Soterix 
Medical, who clarified that “By trained health care practitioner- we simply mean someone who 
is aware of taVNS, technology, risks, etc. and knows how to administer the technique”, and 
“By remote supervision- the system can be self-administered. The subject or caregiver (proxy 
in some cases) would need to be trained on placing the electrodes before they become eligible.  
The system is designed such that the administrator (PI, clinical center personnel,etc) sets the 
desired dose (duration, frequency, pulse width, etc) before handing it off to the subject. The 
subject can only deliver stimulation as prescribed by the clinic [or lab] (i.e. cannot misuse). So 
basically a researcher can remotely supervise administration.” This email correspondence is 
attached as supplementary material. Given this clarification, our study protocol (e.g., with staff 
training participants on electrode placement/device use and subsequent at-home self-
administration with “remote supervision”) is consistent with Soterix Medical’s intended use of 
the device. We will be receiving pictures of electrode placement for each stimulation session. 
Investigational Device Exemption (IDE): An Investigational Device Exemption is not necessary 
per communication with the FDA and rules governing assessment of risk if the study is a non-
significant risk (NSR) investigation. 
 
 
                                
Figure 2 Non-invasive vagal nerve stimulation earpiece placement.   

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Mindfulness Mobile App: The Brightmind mindfulness training app provides lessons by leading 
American mindfulness teacher and neuroscience research consultant Shinzen Young.49 His exercises 
have been shown to be effective in reducing physiological stress reactivity and improving positive 
affect in previous randomized experimental studies among community adults in the Pittsburgh 
area.50,51 A full description of the lessons is attached as supplemental material. Participants in our 
study will be instructed to start with the “Stress Less” introductory course of 8 sessions. Every session 
includes a brief explanation of how the practice helps reduce stress. 
- 
Session 1, Get Grounded – focus on hearing sound or silence, physical body sensations, focus 
on what you see, acknowledge emotional state, let stressful thoughts and feelings come and 
go in the background with relaxed body and slight smile 
- 
Session 2, Relaxation – enjoy rest and relaxation, notice what relaxation feels like by tensing 
and loosening muscles in every part of body, then whole body 
- 
Session 3, Training Positivity – come up with word or phrase that helps overcome stress, 
mentally repeat; find a positive, relaxing mental image, hold it; create positive emotional 
sensation in body that relates to positive phrase and image 
- 
Session 4, Untangle and Be Free – notice mental images or blank screen, notice mental talk 
or silence, notice emotional sensations in body or rest – develop flexibility, observer mindset 
- 
Session 5, Soothing Sound – noting technique – acknowledging and focusing on sensory 
experience - sounds or silence, every few seconds 
- 
Session 6, Focused Relaxation – noting relaxation in body every few seconds, tightening & 
loosening of muscles 
- 
Session 7, Anchoring Awareness in the Body – noting physical sensations, labeling technique 
– name sensory experience, “feel” 
- 
Session 8, You’re Not (Just) Your Thoughts – noting mental talk or silence every few seconds, 
observer mindset, labeling technique – name mental talk “hear”, absence of mental talk “rest” 
 
After finishing the introductory course, participants will gain access to suggested next courses, “Mindful 
Awareness” (7 sessions) and “Deepen Your Practice” (8 sessions). 
 
Participants will be provided a pre-assigned account and password to use with this app, which will be 
accessed by the research team to manage raw data collected through the app (e.g., session type, 
number of sessions, and time spent in the app). The use of pre-assigned accounts and passwords will 
make it such that any data collected by the app will be de-identified.  
 
7. Possible Discomforts and Risk 
7.1 Transcutaneous Vagal Nerve Stimulator. Previous studies using some form of stimulation found 
that some side effects may occur including itching, redness, discomfort, and tingling/mild pain at the 
stimulation site. These side effects usually end shortly after stopping stimulation. If the electrodes are 
not well placed then participants might experience mild pain, although the researchers will adjust the 
electrode placement if this happens. Researchers will also explain how to adjust electrodes for when 
the subjects are at home. Other less common potential side effects (observed in <1% of study 
populations) include nausea, headache, heart palpitations, dizziness, vocal hoarseness, and 
nasopharyingitis.46,47 It is important to note that these less common side effects were primarily found 
in studies of clinical populations with a variety of stimulation methods (e.g., cervical stimulation, 
bilateral stimulation, longer lengths of stimulation) that are not being used in this study. Thus, while 
these side effects have been observed in some prior studies, we do not anticipate that are likely to 
occur in this study of healthy college students.  
We will be using a Soterix Medical taVNS device. Their website describes the device safety thusly:  
 
“taVNS on the other hand, delivers electrical stimulation to the auricular branch of the 
vagus nerve (ABVN), an easily accessible target that innervates the human ear (Peukar 

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     Page 13 of 18 
and Filler 2002). Over the last decade, several groups have demonstrated the safety and 
tolerability of this method, including central and peripheral nervous system effects, and 
behavioral effects in neuropsychiatric populations (Kreuzer et al 2012, Clancy et al 2014, 
Rong et al 2016, Bauer et al 2016 ). taVNS is also being explored in individuals to 
enhance cognitive and social functioning (Jacobs et al 2015,Jongkees et al 
2018,Colzato et al 2018). Furthermore, side-effects of taVNS are minimal, with skin 
irritation or redness being the most common side-effect. In a review of 51 studies with 
1322 human participants receiving tVNS, the most common side effect was local skin 
irritation (%18). Authors conclude tVNS is well tolerated and safe (Redgrave et al., 
2018).”” 
• 
Peuker, E.T., & Filler, T.J. The nerve supply of the human auricle. Clinical Anatomy. 15 (1), 35-37 
(2002). 
• 
Kreuzer, P.M. et al. Transcutaneous vagus nerve stimulation: retrospective assessment of 
cardiac safety in a pilot study. Frontiers in Psychiatry. 3, 70 (2012) 
• 
Clancy, J.A. et al. Non-invasive vagus nerve stimulation in healthy humans reduces sympathetic 
nerve activity. Brain Stimulation. 7 (6), 871-877 (2014). 
• 
Rong, P. et al. Effect of transcutaneous auricular vagus nerve stimulation on major depressive 
disorder: A nonrandomized controlled pilot study. Journal of Affective Disorders. 195, 172-179 
(2016). 
• 
Bauer, S. et al. Transcutaneous vagus nerve stimulation (tVNS) for treatment of drug-resistant 
epilepsy: a randomized, double-blind clinical trial (cMPsE02). Brain Stimulation. 9 (3), 356-363 
(2016). 
• 
Jacobs, H.I., Riphagen, J.M., Razat, C.M., Wiese, S., & Sack, A.T. Transcutaneous vagus nerve 
stimulation boosts associative memory in older individuals. Neurobiology of Aging. 36 (5), 1860-
1867 (2015) 
• 
Jongkees, B.J., Immink, M.A., Finisguerra, A., & Colzato, L.S. Transcutaneous Vagus Nerve 
Stimulation (tVNS) Enhances Response Selection During Sequential Action. Frontiers in 
Psychology. 9, 1159 (2018). 
• 
Colzato, L.S., Ritter, S.M., & Steenbergen, L. Transcutaneous vagus nerve stimulation (tVNS) 
enhances divergent thinking. Neuropsychologia. 111, 72-76 (2018). 
• 
Redgrave J, Day D, Lueng H, Laud PJ, Lindert R, Ali A, and Majid A. Safety and tolerability of 
tVNS in humans; a systematic review. Brain Stimulation 11, 1225-1238.  
 
Note, the devices used in these studies are diverse (all TENS unit variants). Soterix’s device is 
based on their commonly used TENS unit platform used in neuromodulation studies around the 
world (e.g., TDCS). 
7.2 Mindfulness Practice: Mindfulness practice can reveal or bring into greater focus uncomfortable 
thoughts, emotions, or bodily sensations. These experiences are similar to those that a person might 
experience in everyday life or while using other commercially available mindfulness apps. The 
Brightmind Meditation app is structured to begin with positive and relaxing experiences to minimize 
user discomfort or frustration as they develop mindfulness skills.  
7.3 Mood Assessments: Questions about mood and personality can sometimes be uncomfortable 
(e.g., talking about things that make you sad or anxious). If participants experience distress while 
completing these questionnaires, they will be instructed to contact a research assistant who will be 
able to provide community mental health resources. 

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     Page 14 of 18 
7.4 Wearable Sensors: The wrist monitor is comparable to wearing a standard wristwatch. If the  band 
is too tight, there is a risk of skin irritation. Similar risks apply to the chest band. Both bands are 
adjustable to ensure participant comfort. 
7.5 Breach of Confidentiality. Breach of confidentiality is highly unlikely because all information will 
be identified with a participant code and stored in a locked file cabinet. Only study staff will have access 
to this database. All staff are or will be fully trained in relevant ethical principles and procedures, 
including confidentiality. 
Once a participant completes the entirety of the study (i.e. returns the equipment and/or receives 
payment) and the payment is updated according to UF’s Human Participant Payments guidelines, the 
subject’s contact information and student identification/social-security-number will be redacted form 
the questionnaires and payment receipts. 
7.6 Data and Safety Monitoring Plan. The investigative team will meet regularly to discuss data and 
safety monitoring issues. Any issues identified during the course of these meetings will be handled in 
a manner consistent with the University of Florida’s policies. 
 
8. Possible Benefits 
A potential benefit of participating in this study is experiencing a short-term improvement in mood and 
sleep quality. No direct long-term benefits can be reasonably expected from this study, except if the 
mindfulness training app intervention shows preliminary efficacy and participants continue using it on 
their own after the study is over. The information garnered from this study may provide valuable data 
on the optimization of the tVNS technology, which has the potential to be a cheap, effective, and safe 
tool for augmenting effects of mindfulness practice. 
 
9. Conflict of Interest 
There are no known conflicts of interest. 
 
10.  Participant Payment 
 
Participants will be compensated for their time and effort participating in the study. The amount is 
specified on my.irb.ufl.edu and the consent form. 
 
 

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     Page 15 of 18 
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