The relationship between time spent using the Happy Days Mental Heath app and heart rate

Happy Days Mental Health logo: Created by Freya Mannisto

Scratch components of app (including worry rocket, breathing bubble, and sound library): Created by Freya Mannisto on the finko_ravenclaw Scratch account: https://scratch.mit.edu/users/finko_ravenclaw/

I was inspired to do this project three years ago when I became aware of mental health issues around the world and how difficult it is to find mental health apps for teenagers. With my experience coding since grade 3, I felt confident about developing the Happy Days Mental Health app for teenagers and I later experimented to see its effect on calming the body.

In my background research on what controls heart rate I discovered that the autonomic nervous system is responsible.  This system consists of two divisions: the sympathetic and parasympathetic nervous systems (Donato, 2018).  The sympathetic nervous system is activated when your body enters fight-or-flight mode causing heart rate to increase. When the parasympathetic nervous system is activated your body enters a state of serenity causing heart rate to decrease (Cleveland Clinic, 2022a).  The aim of my app is to successfully activate the parasympathetic nervous system in the users, calming them mentally and physically.

I hypothesized that if the time the app was used for increases, then heart rate would decrease.  I thought this because the participants in the experiment would be engaged in the app activities for a longer period of time activating the parasympathetic nervous system.

My experiment can provide insightful data for app developers and can benefit many people including teenagers struggling with mental issues.  I believe there should be more awareness towards this population to ensure the world has a content future.

Materials:

Samsung Fit 3 Smartwatch to measure heart rate and time the app was in usage (with the stopwatch feature).

Two laptops as I experimented on two participants at the same time.

Procedure:

Trials:

Five 15-year old males used the app for specified amounts of time (3,5,7,9, and 11 minutes).  Each participant did 5 trials with their designated amount of time and participants were tested on 2 at a time on separate laptops.

Participants sat in the experiment environment for 5 minutes before starting the procedure.

Participants were given a pre-app usage survey where they indicated their current mood, stress level, and if they thought the app will help them.

The smartwatch was strapped to the wrist of participants in order to get a pre-app usage heart rate.

Participants then engaged with the app activities for their assigned amounts of time and used the tools in the following order: affirmations, worry rocket, mood meter, doodling, calming sounds, and the breathing bubble.

After their assigned amounts of time were completed, post-app usage heart rates were taken through the usage of the smartwatch.

Participants were given a post-app usage survey in which they answered questions similar to the pre-app usage survey.

Controlled variables

The gender of the participants was kept the same (Cleveland Clinic 2022b).

The diet of the participants was controlled with no caffeine ingested up to 6 hours before participating in the experiment (AdventHealth Cardiology Team, 2025) and this also applied for spicy and surgery foods.

The environment and time of day the experiment was conducted was kept the same.

Each participant rested for 5 minutes before beginning the procedure

Participants were not on any medications or were living with health issues that affected heart rate.

My overall results were that the more time the app was in usage, the more the heart rate

decreased.

The participant who used the app for 3 minutes had an average change in heart rate of +4 BPM and indicated on his survey that he thought the app did not affect his mood or stress level at all. This suggests that 3 minutes of app usage was not long enough to have a meaningful impact on the body. The participant who used the app for 5 minutes had an average change in heart rate of -4 BPM and the participant also indicated on the survey that the app improved well-being for the majority of the time. The participant who used the app for 7 minutes had a change in heart rate of -4.5 BPM but indicated on his survey that the app was unhelpful for well-being.  This may suggest that physically, this participant was calm but mentally, he may not be accepting that the app was helping him.

The participant who used the app for 9 minutes had an average change in heart rate of -15 BPM. Interestingly, he indicated for 3 of the 5 trials that the app did not change mood or stress level but for the 4th and 5th trials he began to believe that the app was benefiting him and he enjoyed using it.  The participant who used the app for 11 minutes surprisingly had the same survey results but had an average change in heart rate of -15.2 BPM.

There is an outlier evident in the scatterplot displaying all 25 changes in heart rate.  The outlier is the participant who used the app for 9 minutes and it displays a change in heart rate of -32 BPM.  This is a large change and this may have happened because the participant could have been running, walking, or had stress before doing the experiment so the heart rate could have been higher than normal and went down while using the app due to activation of the parasympathetic nervous system.

Data analyses

To display these results, Microsoft Excel was used and a line graph and scatterplot were created to show quantitative trends.  Qualitative results were displayed in a chart.  Error bars were added into the average change in heart rate line graph.  According to Samsung Canada, the watch used to measure heart rate had an uncertainty measurement of +/- 1.5 BPM.  The uncertainties of the heart rate measurements per participant were calculated through the quadrature and mean error determination methods.  To do this, the square root of 1.52+1.52 was taken which was rounded to be 2.  To find what the uncertainty measurement for each person was, 2 was divided by the square root of 5 as there were 5 participants.  This final number rounded to 1 giving me the measurement of +/- 1 BPM.

From my results, it was learned that the Happy Days Mental Health app can successfully decrease in heart rate and calm down the body and mind. This likely occurred due to the activation of the parasympathetic nervous system. This supported my initial hypothesis and it was also found that the heart rate decreased more consecutively and consistently with the more time the app was in usage.  It was discovered that 3 minutes of app usage was not effective in calming the body or mind.

It is likely this phenomena occurred due to activation of the parasympathetic nervous system which is triggered causing the body to go into a state of serenity (Cleveland Clinic, 2022).  This system releases the neurotransmitter acetylcholine which sends signals throughout the body causing the decreased heart rate and calming of the rest of the body (Tindle & Tadi, 2022).

In conclusion, the Happy Days Mental Health app is helpful for mental health and this was demonstrated through the experiment conducted due to the multiple constants in place and multiple trials done for each of the participants.

If this experiment were to be conducted in the future, some improvements are that each participant could be wearing the watch for the entirety of experiment duration (instead of only before and after app usage) to obtain more accurate readings.  A different device could  be used to measure heart rate such as an oximeter.  A control group of participants who did not use the app could be added.  I would love to take this project further and experiment to see the effect of the app on female heart rates or studying how different tools on the app affect heart rate.

I would like to express gratitude towards my teacher Mrs. Marshalok who gave me support and encouragement throughout the process of my experiment- without her, this project would not have existed.

I would also like to thank the whole NWORSF team for their continuous support.  Mrs. Cross and Mr. Pilot always offered guidance whenever I needed it as well which I am endlessly grateful for.

Additionally, I want to thank everyone at Hackergal for keeping my coding talent alive all these years.

Special thanks to Mr. McCreery who got me started in coding back in grade 3 and made this project a reality.

Mr. Stevens is another figure I would like to thank for his support and encouragement.

Lastly, I would like to thank my whole family including my parents and my dog Finko- I am so grateful that I am surrounded by so much love and support every day.

Links to the Google Docs on which all information was originally written:

Why: https://docs.google.com/document/d/1Ezu8T_lLNmTJEswEGfK4_YPsj6KLWvE6LZ5u597uWL0/edit?usp=sharing

All other ProjectBoard sections:

https://docs.google.com/document/d/1Dp20xfEZtQmJ__vJBUkP4FlxJVlbDshGcLabu-Sy_iI/edit?usp=sharing

Scratch components of app (including worry rocket, breathing bubble, and sound library): created by Freya Mannisto on the finko_ravenclaw account

Images:

Nall, R. (2020, April 23). The Parasympathetic Nervous System Explained. Healthline. https://www.healthline.com/health/parasympathetic-nervous-system

Terraillon (n.d). "Learning": Cardiac coherence, what is it?. Terraillon help center. https://terraillonhelp.zendesk.com/hc/en-us/articles/360010300319--Learning-Cardiac-coherence-what-is-it

Molnar, C., & Gair, J. (n.d.). 16.4 The Peripheral Nervous System. Concepts of Biology - 1st Canadian Edition. https://opentextbc.ca/biology/chapter/16-4-the-peripheral-nervous-system/

Information:

AdventHealth Cardiology Team. (2021, September 27). How Does Caffeine Affect Your Heart? AdventHealth. https://www.adventhealth.com/blog/how-does-caffeine-affect-your-heart

Akinrodoye, M. A., & Lui, F. (2022, November 7). Neuroanatomy, somatic nervous system. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK556027/

American Heart Association. (2024, May 13). All about Heart Rate. American Heart Association; American Heart Association. https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/all-about-heart-rate-pulse

Bentley, T. G. K., D’Andrea-Penna, G., Rakic, M., Arce, N., LaFaille, M., Berman, R., Cooley, K., & Sprimont, P. (2023). Breathing practices for stress and anxiety reduction: Conceptual framework of implementation guidelines based on a systematic review of the published literature. Brain Sciences, 13(12), 1612. https://doi.org/10.3390/brainsci13121612

Byjus. (2018, July 31). Difference Between Sympathetic And Parasympathetic. BYJUS. https://byjus.com/biology/difference-between-sympathetic-and-parasympathetic/

Canadian Mental Health Association. (2021, July 19). Fast facts about mental health and mental illness. CMHA National; Canadian Mental Health Association. https://cmha.ca/brochure/fast-facts-about-mental-illness/

Cleveland Clinic. (2021, September 1). Heart rate variability (HRV): what it is and how you can track it. Cleveland Clinic. https://my.clevelandclinic.org/health/symptoms/21773-heart-rate-variability-hrv

Cleveland Clinic. (2022a, June 15). Autonomic Nervous System: What It Is, Function & Disorders. Cleveland Clinic. https://my.clevelandclinic.org/health/body/23273-autonomic-nervous-system

Cleveland Clinic. (2022b, July 28). Women and Heart Rate: What’s Normal & What Impacts It. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/17644-women-and-heart-rate

Cleveland Clinic. (2026, April 14). Nervous system. Cleveland Clinic. https://my.clevelandclinic.org/health/body/21202-nervous-system

Donato, A. (2018, October 9). Autonomic nervous system. Uq.edu.au. https://qbi.uq.edu.au/brain/brain-anatomy/peripheral-nervous-system/autonomic-nervous-system

Kenhub. (2019, April 15). Autonomic nervous system. Kenhub; Kenhub. https://www.kenhub.com/en/library/anatomy/autonomic-nervous-system

Oldehinkel, A. J., Verhulst, F. C., & Ormel, J. (2008). Low Heart Rate: A Marker of Stress Resilience. The TRAILS Study. Biological Psychiatry, 63(12), 1141–1146. https://doi.org/10.1016/j.biopsych.2007.12.006

Romero, A. (2024, February 7). Galaxy Fit 3 user manual appears online, early store appearance with price revealed. 9to5Google. https://9to5google.com/2024/02/07/samsung-galaxy-fit-3-manual-price/

Tindle, J., & Tadi, P. (2022, October 31). Neuroanatomy, Parasympathetic Nervous System. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK553141/

Sounds (from the sound library)

Piya: Royalty Free Music - No Copyright Music. (2022, February 12). Copyright Free Waterfall Sound | Royalty Free Background Music | Download Now [Video]. YouTube. https://www.youtube.com/watch?v=A36GvwxSE5U

Teodor MIHALACHE. (2017, August 23). Rain Sounds 15 seconds soundtrack [Video]. YouTube. https://www.youtube.com/watch?v=C-hzP3mOBGY

Sound FX. (2022, October 4). WHITE NOISE SHORT CLIP - FREE [Video]. YouTube.

https://www.youtube.com/watch?v=WKT5yPy9Nxw