Key Takeaways
1.Stress isn’t just bad for your mood. It can cause shallow breathing, a faster heart rate, and poorer recovery.
2.PPG- and HRV-based models can help show stress trends but can’t replace medical diagnosis.
3.Slow breathing may help the body slow down through vagus-nerve activity, HRV changes, and baroreflex regulation.
4.Try 20 minutes daily, or as little as 5 minutes a day; both may bring measurable changes.
5.If you’re feeling tense, restless before bed, or seeing rising stress indicators on CUDIS, try breathing techniques to help bring your body back toward balance.
5 Min Read
Stress goes beyond heavy workloads, restless minds, and strained emotions.
Your body will also start sending warning signs:shallow breathing, a racing heartbeat, tight neck and shoulder muscles, reduced appetite, and a mind that won’t quiet down at night.
Telling yourself not to overthink won’t solve it. Stress is not just a mental issue; it is a whole-body response.
Deep breathing can come in handy in such moments.
What Stress Does to Your Body?
Short-lived stress isn’t entirely detrimental.
Your body enters a state of “fight-or-flight” before exams, speeches, competitions, or deadlines, becoming more alert, focused, and responsive.
Long-term exposure to high stress may impair sleep, recovery, concentration, and emotional stability, and may also increase cardiovascular strain.
However, many people adapt to ongoing tension and mistakenly believe they are being “efficient”.
Knowing your own stress level may help you steer clear of issues stemming from inadequate recovery.
PPG (photoplethysmography) is one way to observe body signals. It uses light to detect changes in blood volume, allowing estimates of health metrics such as heart rate, heart-rate variability, and blood-oxygen levels.
A APL Bioengineering study showed that PPG-based HRV analysis combined with machine learning may help quantify real-time psychological stress.
Researchers found that the stress score derived from PPG signals and algorithms showed a strong correlation with participants’ DASS-21-C stress scores (r=0.92) (Tsai et al., 2025).
DASS-21-C, used in this study, is the Chinese version of the Depression Anxiety Stress Scales-21. It is a commonly used self-report scale for assessing subjective stress over the past week.
The strong correspondence between PPG-based stress scores and this scale suggests that PPG models can, to some extent, reflect the body’s stress load.
CUDIS, as a smart ring that uses PPG technology, can also indicate daily stress trends and turn abstract feelings of “tired” and “tense” into more observable changes.
Of course, it can’t diagnose stress disorders or replace medical care. It can remind you when your body may be under more stress than you realize.
Why Breathing May Help?
Popular relaxation breathing exercises are listed below:
· Diaphragmatic breathing – focus on belly rise and fall.
· Paced breathing – slow your breath and keep a steady rhythm.
· Prolonged exhalation – make the out-breath slightly longer than the in-breath.
· Box breathing – follow an even rhythm as you breathe in, pause, breathe out, and pause again.
They all share the same core feature: turning unconscious breathing into a controllable entry point.
When you inhale, changes in chest pressure can briefly raise heart rate; when you exhale, vagus-nerve-related regulation becomes more apparent, and heart rate is more likely to slow down.
At the same time, a slower rhythm may improve baroreflex regulation, helping heart rate, blood pressure, and breathing work in better harmony.
A randomized controlled trial in Cureus divided 50 healthy adult men into two groups: one practiced normal breathing, while the other received resonance breathing training and then practiced for 20 minutes each day for four weeks.
Researchers compared HRV and perceived stress before and after the intervention.
Results showed that compared with the normal breathing group, the resonance breathing group had significantly lower perceived stress scores and improvements in some HRV measures such as SDNN and pNN50 (Chaitanya et al., 2022).
Previous articles have noted that HRV is associated with changes in subjective stress.
After perceived stress rises, HRV may decrease within the following 10 minutes; lower HRV during the previous hour may also predict higher perceived stress later on (Kim et al., 2024).
Breathing exercises are not a universal solution, but they can help the body practice switching between stress and relaxation.
Breathing exercises are affordable and convenient.
A Cell Reports Medicine study compared three different daily 5-minute breathing exercises with mindfulness meditation.
Results showed that exhale-focused cyclic sighing performed better in improving mood and reducing respiratory rate, suggesting that short daily breathing practice may bring visible changes (Balban et al., 2023).
Lengthy practice is not always necessary. Sometimes, five minutes is enough to help the body loosen up first.
When to Use Deep Breathing?
Use deep breathing before you’re overwhelmed and when you notice physical tension.
In daily life, this might be when your mood suddenly rises, your mind won’t quiet down before bed, or an argument keeps replaying in your head.
A few rounds of breathing are not about suppressing emotion; they are about keeping the body from accelerating further. When the body slows down, rational thinking has a chance to return.
At work, before stressful meetings, after prolonged intense focus, or after high-pressure tasks, try two to five minutes of breathing as a transition. It may help lower your heart rate and ease muscle tightness, making it easier to think clearly.
Data can also indicate when slowing down may be necessary.
When CUDIS shows low HRV, high RHR, and a rising stress index, your body may be carrying more background load than you realize.
Pause and take a few slow, diaphragmatic breaths.
Breathing Techniques You Can Try
Diaphragmatic Breathing
Rest one hand on your chest and the other on your abdomen. As you inhale, feel your belly gently expand; as you exhale, let it fall back naturally.
The objective isn’t to draw a large breath at a time but to avoid shallow, rapid chest breathing.
Prolonged Exhalation
Start by inhaling for 4 seconds and exhaling for 6 seconds. A slightly longer exhale gives your body more time to relax.
This works well before bed, after an argument, or after training.
Box Breathing
Breathe in for 4 seconds, pause for 4 seconds, breathe out for 4 seconds, and pause again for 4 seconds.
Keep a calm, steady rhythm to help focus before a meeting.
Breathing can be a powerful reset mechanism: when stress is pushing you forward, it can help bring your body back toward balance.
As physical calm is restored more quickly, the way you manage stress may gradually change.
You don’t have to tough out every stressful moment. Sometimes, one slow, full breath can help your body get back in rhythm.
References
Balban, M. Y., Neri, E., Kogon, M. M., Weed, L., Nouriani, B., Jo, B., Holl, G., Zeitzer, J. M., Spiegel, D., & Huberman, A. D. (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine, 4(1), 100895. https://doi.org/10.1016/j.xcrm.2022.100895
Chaitanya, S., Datta, A., Bhandari, B., & Sharma, V. K. (2022). Effect of resonance breathing on heart rate variability and cognitive functions in young adults: A randomised controlled study. Cureus, 14(2), e22187. https://doi.org/10.7759/cureus.22187
Kim, J., Foo, J. C., Murata, T., & Togo, F. (2024). Reduced heart rate variability is related to fluctuations in psychological stress levels in daily life. Stress and Health, 40(5), e3447. https://doi.org/10.1002/smi.3447
Tsai, Y.-Y., Chen, Y.-J., Lin, Y.-F., Hsiao, F.-C., Hsu, C.-H., & Liao, L.-D. (2025). Photoplethysmography-based HRV analysis and machine learning for real-time stress quantification in mental health applications. APL Bioengineering, 9(2), 026103. https://doi.org/10.1063/5.0256590
