Can Positive Affect Raise HRV? What 36 Studies Really Show

Feeling calm and satisfied may track with higher resting heart rate variability (HRV). Feeling excited and energized may do the opposite. That distinction matters for anyone treating HRV as a score to improve with breathwork, cold exposure, and training.

A 2025 systematic review by Martha Schneider and colleagues examined 36 studies involving 5,501 people ages 9 to 82. Across laboratory, cross-sectional, and ambulatory designs, people with higher trait positive affect—and people experiencing low-arousal positive states such as contentment or calm—generally had higher vagally mediated HRV at rest. The review did not pool the studies into one effect estimate, so it cannot tell us how large the average association is or whether it would produce a meaningful change on your wearable.

It does, however, make one point harder to ignore: HRV is not only a physiological readout. It also relates to how the brain regulates emotion, attention, and stress. The catch is that the evidence does not yet show that deliberately making yourself happier raises resting HRV.

Positive affect has two different autonomic signatures

Psychology often lumps pleasant emotions together. Your autonomic nervous system does not. The review separates activated positive affect—excitement, enthusiasm, elation—from deactivated positive affect, including relaxation, contentment, and quiet satisfaction.

Activated positive affect tends to raise heart rate and suppress high-frequency HRV (HF-HRV). That pattern fits sympathetic activation: the body is mobilized, even if the experience feels good. Deactivated positive affect instead tracks with greater parasympathetic activity and higher measures such as RMSSD, a common time-domain HRV metric.

This is why a high-energy gratitude ritual or an achievement-focused visualization should not automatically count as an HRV-supportive practice. It may be psychologically useful, but its acute autonomic signature can differ sharply from a calm practice. The literature offers no dose guidance for positive-affect interventions and no validated protocol for tuning their arousal level.

Why mood could relate to HRV

The leading explanation is the Neurovisceral Integration Model. It proposes that prefrontal brain networks involved in attention and self-regulation communicate with brainstem vagal centers, including the nucleus ambiguus and dorsal motor nucleus. Under that model, emotional regulation and cardiac parasympathetic control are linked through shared circuitry.

A 2023 biofeedback study by Lukas Bögge and colleagues supports the reverse side of that relationship. Respiratory sinus arrhythmia during biofeedback was linked to persistent improvements in attention, short-term memory, and positive self-referential episodic memory. It suggests that changing autonomic state can affect cognition and emotional processing. It does not prove that increasing positive affect, by itself, raises resting HRV.

The review also discusses Broaden-and-Build theory: over time, positive affect could reduce stress reactivity and help sustain autonomic balance. That is plausible, but a plausible pathway is not a completed causal chain. Most studies in the review measured association at one time point or over short observation windows. Only one of the 36 studies used a longitudinal design.

The stronger alternative: HRV may buffer distress

Two ambulatory studies complicate the appealing story that positive mood drives vagal tone upward. A 2024 daily-life study by Lauren Bylsma and colleagues found that resting vagally mediated HRV measured in the laboratory related primarily to momentary negative affect and negative-emotion regulation in everyday life, rather than to positive affect.

Similarly, Chelsea da Estrela and colleagues' 2021 ambulatory multilevel study found that HRV moderated the relationship between daily stress and negative affect. People with higher resting HRV showed less conversion of stress into negative affect at both between-person and within-person levels.

These studies support a protective-buffering interpretation. Higher vagal tone may help people recover from stress and downregulate unpleasant emotion. If so, people with higher HRV may report more positive affect partly because negative affect takes up less space, not because positive affect directly increased HRV. The available evidence cannot distinguish these explanations cleanly.

Calm positive affect and higher resting HRV travel together in the literature. The direction of travel remains unsettled.

Mind-body practices improve HRV, but breathing is the obvious confounder

Meditation, Tai Chi, and multi-component practices can improve vagally mediated HRV. A 2021 meta-analysis of mindfulness and meditation found that these practices increase vagally mediated HRV. A 2024 systematic review and meta-analysis of Tai Chi also reported HRV improvements.

Neither finding isolates positive affect as the active ingredient. Meditation can change breathing, relaxation, attention, and affect at the same time. Tai Chi adds slow rhythmic movement and controlled breathing. Those ingredients all affect HRV, especially HF-HRV, which is highly sensitive to respiratory pattern.

The same problem applies to a 2023 randomized trial of a 15-week Wim Hof Method protocol. The intervention combined cold exposure, specific breathing, and meditation and documented cardiac autonomic improvements. It cannot tell us which component caused them.

For now, the most defensible attribution is breathing first. Positive affect may contribute, but current intervention studies cannot quantify that contribution independently.

What the review can and cannot establish

The 36-study review is broad, but its limitations shape the conclusion. Participants were 80.6% female, limiting confidence about how well the findings generalize to men. The studies covered people ages 9 to 82 and mixed laboratory, clinical, and everyday settings. That breadth is useful for spotting a pattern, but it also makes a single practical estimate impossible.

Physical fitness remains a major unresolved confounder. None of the reviewed studies simultaneously adjusted for VO₂max, physical-activity frequency, and body mass index while reporting the positive-affect–HRV association. Active people may have both higher HRV and higher trait positive affect for reasons unrelated to a direct psychological effect.

The review included 36 studies from 411 initial search hits, an 8.7% inclusion rate, and did not report a publication-bias correction. That does not invalidate the association, but it means published findings may overstate its magnitude. A 2023 study of trait positive affect during a standardized stressful situation also reported mixed results, suggesting that stress context may alter the association.

Most importantly, no trial in this evidence base tested a standalone positive-affect intervention—such as gratitude journaling, loving-kindness practice, or positive-affect skills training—with resting HRV as its primary endpoint. No study compared such an intervention directly with resonance breathing or exercise training.

A practical HRV strategy

Exercise still has the firmer intervention evidence. A 2024 meta-regression and trial sequential analysis of exercise training found that exercise augments HRV during and after training. That does not make psychological factors irrelevant; it means the two approaches do not carry equal evidentiary weight.

• Use slow, comfortable breathing and regular exercise as the foundation if your goal is to improve HRV.
• Add practices that cultivate calm satisfaction, relaxation, or contentment if they help you recover and reduce stress.
• Do not assume excitement, intense motivation, or euphoric gratitude will raise HF-HRV in the moment. They can lower it.
• Judge a practice by trends in standardized resting measurements and by how you feel and function, not by a single post-session HRV reading.
• Treat persistent anxiety, chronic worry, trauma symptoms, or severe stress as health concerns worth addressing directly rather than trying to out-gratitude them.

The current evidence supports a modest conclusion: positive affect, especially calm positive affect, is associated with higher resting vagal HRV. It does not show that a happiness practice can replace exercise, sleep, or respiratory training. The more useful psychological target may be reduced reactivity to stress rather than a larger dose of enthusiasm.