MOODS is a study focused on determining and measuring your daily stressors

What does it do?

Uses smartphone and wearable technology to measure your stress levels throughout the day.

How does this research help advance science?

Results from this study may help society better understand stress and stressor detection through the exploration of complex interactions between stress, daily behaviors, and environmental factors.

Who is it for?

Residents of the United States are welcome to sign up to potentially participate in the study.

MOODS Participation



Recorded Stressors


Participate in the MOODS study

We have concluded recruitment for the MOODS Study. We thank all who have engaged with our study team for their interest and participation.


  • General Info

    What is the purpose of the MOODS study?

    The purpose of the Mobile Open Observation of Daily Stressors (MOODS) study is to understand what causes stress (i.e., what are the daily stressors) in daily life, focusing on those stress events that can be detected by smartwatches.

    Who can join the MOODS study?

    Any adult (18+) residing in the United States who meets the eligibility criteria for the study (criteria) can apply to participate in the MOODS study.

    How long is the MOODS study for?

    Each participant is asked to participate in the study for 100 days, using the MOODS app daily, wearing the study-provided smartwatch, and completing weekly app-based surveys. Participants will receive weekly visualizations of their data, showing patterns of their daily stressors.

    What is the MD2K Center of Excellence?

    The Center of Excellence for Mobile Sensor Data-to-Knowledge (MD2K), headquartered at University of Memphis, was established via a grant (#U54EB020404) from the National Institutes of Health (NIH) in 2014 to develop novel computing technologies to use mobile sensor data for improving health and wellness.

    Can I continue in the MOODS study beyond the required 100 days?

    Yes, while the study is still ongoing. Once the study concludes, you will be notified that the MOODS study and apps will be shut down, and you should uninstall the MOODS app from both the smartwatch and your phone. If you continue using the apps after the study has concluded, the apps' functionality may stop working.

    Can I keep the smartwatch when/if I complete the full study?

    Yes, if you fulfill all requirements and complete the study. A full description of study requirements is located in the study’s informed consent document.

  • Phone App

    How do I install the app?

    Upon registration, if you are considered eligible, you will receive an invitation via email that will contain detailed instructions.

    How do I use the app?

    After you install the app, you will be asked to carefully read the informed consent form. If you agree to participate, we will send you a smartwatch for use in this study. The smartwatch should be paired (connected) with the MOODS app upon receipt, using the instructions that we will provide you. Your MOODS app and smartwatch will then begin collecting study data. You will then begin to receive daily notifications on your phone to confirm stress events and identify stressors. The app will also notify you each week to complete in-app surveys.

    Can I reinstall the app?

    Yes. You can navigate to the Google Play / Apple App Store on your device and either search for the MOODS app or reinstall it from your library. Once you log back into the app with the same credentials, it will automatically load your previous data.

    Does the app use my cellular data?

    Yes. The app sends a small amount of data to the server for the purposes of logging stress and non-stress events on the server. During the review process, it receives data from the server to power the process. The watch will send bulk data transfers only while charging and connected to a Wi-Fi network (typically at home while you sleep). Data rates may apply to use the app depending on your cellular plan.

    What should I do if I am already wearing a smartwatch?

    If you are already wearing a smartwatch, you can either choose to wear both watches on the same wrist or on different wrists. No interference is expected.

    Can I use my own smartwatch for the MOODS study?

    No, at this time the MOODS app can only be installed on the study-provided smartwatch.

    How does the MOODS app affect the smartphone battery life?

    The MOODS app on your phone communicates over Bluetooth with the smartwatch when a stress/non-stress episode has been detected. These episodes are then transferred to our servers via the internet. The MOODS app should have a minimal impact on your smartphone’s battery life.

    Can I install or use other apps on the smartwatch?

    Installing or heavily using other apps is likely to further reduce the smartwatch’s battery life. Therefore, it is recommended to minimize the usage of the study-provided smartwatch for other purposes during the 100-day study duration.

    Should I wear the smartwatch in my dominant or non-dominant hand?

    You can choose to wear the smartwatch on either wrist.

    How long should I wear the watch daily?

    Stress episodes can be detected only when the smartwatch is worn and fully functional. We expect the smartwatch to last approximately 6 hours on a full charge. We provide an additional (second) charger with the study-provided smartwatch so that you can charge it again and wear it for the rest of the day, if convenient. Please keep the watch on the charger while you sleep so that it is fully charged for the next morning and collected data can be uploaded.

    Can I change the time of the notifications?

    Yes, you can go to "Settings -> Change daily notification time" in order to set up your preferred notification time. We suggest that you set a time in the evening so you will have time to review the weekly visualizations.

    What are the episodes that are shown in the app for stressor annotation?

    These episodes consist of time intervals when the smartwatch detects that you may be either stressed or not stressed. The reason for showing a mixture of both event types is to obtain an unbiased evaluation of the MOODS stress model.

    Can I come back later to the app for annotating the episodes?

    No, the annotation process must be completed once you open the app after you receive the notifications. This helps us to ensure that you are annotating your most recent recollection of the stress event(s).

    What do I enter in the app if I am not able to recall the stressor?

    You can type in "Can't recall", but this will limit your ability to see the patterns in different stressors because these episodes may not be included in your data analysis. You may also manually enter stressors anytime (ideally, soon after the event) via the MOODS app home screen on your phone.

    What does the "Make Episode Private" function do?

    If you mark an episode as "private", it will be removed from your list of stress episodes. The MOODS research team will still be able to see the episode, but the episode will not be shared outside of the study team or used for research.

    Can I manually add stress episodes?

    Yes! The MOODS smartphone app provides an option to manually add stress episodes via the app’s home screen. We encourage you to manually add stress episodes soon after the event so that you can best remember what caused the stressful event.

  • Watch App

    Is it mandatory to download WearOS to use the MOODS app on the smartwatch?

    Yes, the smartwatch is only functional if it is set up through WearOS.

    Why is my watch running so slow?

    The MOODS software utilizes a significant portion of the resources on the watch. We do not recommend adding a bunch of extra capabilities and/or integrations with other phone apps for the duration of the study. Using the watch for receiving notifications and text messages should work well; however, other tasks such as run tracking or navigation will overburden the system.

    Do I need a Google account to download and use the WearOS app?

    Yes. iOS users can download the WearOS app on the phone. A Google account is required to download the necessary application to the watch.

    Can I control what information is collected by the WearOS app?

    Yes. You can modify the settings on Android or iOS. This article has information about how to modify the settings: (note: this link is external to our website and is governed by a separate privacy policy and terms of use)

    Please note that all phone and watch application permissions must be approved for the study applications to run properly.

    What does the Privacy Button do?

    The Privacy Button in the MOODS watch app interface allows for you to pause data collection. This means that the watch will not collect information about your motion (activity), heart rate (for stress computation). This function was designed to allow you to pause data collection for any reason without having to remove the study smartwatch. The privacy mode will automatically turn off after one hour so that you don’t forget to turn it back on, but it can be turned on again if you’d like additional privacy. If the privacy mode is turned on very close to a stress episode, a location may still be recorded by the MOODS app. If this happens, you can always mark the episode as “Private” via your phone if you wish.

  • Stress

    What is stress and how is it calculated?

    Stress is a dynamic process that reflects the brain’s response to internal and external factors, characteristics of a person and their circumstances, and interactions between people. Stress may include interpersonal negative affect events such as conflicts, anger, frustration, and neutral events of high cognitive load such as engaged conversation, brainstorming, deep thinking, etc. The MOODS app uses algorithms to automatically analyze your heart rate via the LED sensor on the smartwatch. By applying a trained machine learning model, the MOODS app infers whether a physiological arousal is indicative of stress.

    What is a stressor?

    A stressor is an event, thought, threat, or challenge, i.e., “precipitant” that may trigger stress.

    What is stress probability?

    According to your sensor data, stress probability is the model’s guess with respect to how likely you are to be stressed.

  • Privacy

    Does the MOODS app collect and/or share personally identifying information?

    We need your identifiable contact information such as name, address, and email address in order to ship the smartwatch and to send the weekly study emails. We may also correspond with you, and you may ask us questions via email to ensure the study data collection is running smoothly. This identifying information is not shared with anyone outside the study team and is also not released or shared with any of the study data for research purposes.

    We collect your GPS location when stress episodes are detected by the smartwatch. This is used to visualize and analyze the impact of location on stress and stressors. We will only share de-identified semantic locations (non-identifiable labels like “home” or “workplace”) when these data are shared more broadly.

    We also collect some non-personally identifiable information from the smartwatch and study platforms like motion sensors (accelerometer, gyroscope), heart rate information from the smartwatch LED sensors, and stress episodes calculated from the smartwatch. After the study, we plan to share portions of de-identified data publicly to accelerate research by the community.

    More detailed information about study privacy and confidentiality is located in this study’s informed consent document.

    What data does the app automatically collect?

    The MOODS app automatically collects accelerometer, gyroscope, LED, and GPS data from the smartwatch. This information is then used to compute inferences of whether you are stressed, your activity (e.g., whether you are moving, driving, or still), and other inferences as described in the informed consent document.

    Can I pause or turn off data collection?

    Yes. You can turn on the privacy mode in the MOODS app screen via the smartwatch to stop data collection. A description of this function is located in the Watch App section of this FAQ.

    Who will have access to the collected data?

    Authorized researchers working with the study team will have access to the data. We also plan to publicly release the de-identified dataset to the research community, i.e., the released dataset will not contain any identifying information such as your personal information or raw GPS.

    What purposes will the data be used for?

    We will only use your contact information for the purposes of contacting you about this research study, and future research studies if you choose. We will use your research data for scientific progress and for the publication of study results. Please refer to the informed consent document for more information about data usage and sharing.

Website Disclaimer

Last Updated May 19, 2021

The Center of Excellence for Mobile Sensor Data-to-Knowledge at the University of Memphis (MD2K) is the owner and creator of the MOODS mobile application (Mobile App) and its associated websites ( (Website). Both the Mobile App and the Website are offered as parts of a research study, as overseen by an Institutional Review Board (IRB). Both are informational only and neither is intended as a substitute for medical advice. There is no guarantee as to the accuracy, availability or completeness of the information contained within the Mobile App, the Website, or in any of their links.

Neither MD2K nor the University of Memphis is responsible for any damages arising out of the use of, reference to, or reliance on any information contained within the Mobile App, the Website, or in any of the links or information therein.

Construction of this Disclaimer and resolution of disputes thereof are governed by the laws of the State of Tennessee.