The clinical value of circadian biofeedback in chronic heart failure

Abstract Background Chronic heart failure (CHF) is characterized by impaired autonomic regulation and disrupted sleep–wake cycles, leading to fatigue, poor recovery, and reduced quality of life. Conventional management focuses on medication and symptom control but rarely addresses behavioral rhythm and recovery. CircAlign-HF (Figure 1) was developed as a wearable-guided circadian biofeedback system designed to helping patients regain control by translating continuous physiological monitoring into personalized guidance on optimal times for activity, rest, and sleep—promoting daily rhythm restoration and autonomic balance. Purpose To evaluate whether wearable-guided circadian feedback can enhance daily rhythm alignment, autonomic regulation and perceived wellbeing in patients with CHF compared with standard behavioral advice. Methods Twenty-one patients with stable CHF (median age 68 years IQR 61–76, 90.5% male, LVEF 45% IQR 30–50.5, NYHA II–III) completed a three-week crossover protocol. Week 1 served as baseline mapping; Week 2 provided general advice (30-min daily walk, 20-min nap, sleep hygiene); Week 3 delivered circadian biofeedback with individualized timing derived from heart rate cosinor analysis. Autonomic regulation was assessed using synchronized ECG and actigraphy recordings to derive HRV metrics over 24 hours and within 15-minute windows centered on each participant’s diurnal acrophase (peak activity) and nocturnal nadir (deep sleep). A structured questionnaire assessed adherence, perceived sleep quality, and energy stability. Results General advice improved overall autonomic regulation: the root mean square of successive differences (rMSSD) increased from baseline to Week 2 (+18.2 ms, p = 0.037), accompanied by gains in the standard deviation of NN intervals (SDNN) and rMSSD during peak activity windows (+47.3 ms and +56.8 ms, both p = 0.037). Circadian-aligned feedback (Week 3) specifically enhanced nocturnal recovery, reflected by higher SDNN (+56.7 ms, p = 0.039), rMSSD (+47.6 ms, p = 0.0078), low-frequency (LF) power (+6236 ms², p = 0.039), and high-frequency (HF) power (+6812 ms², p = 0.0078) compared with baseline (Figure 2). Adherence rates were 68% for walks, 74% for naps, and 47% for circadian timing. Over half of participants reported deeper sleep and steadier daily energy, describing the self-management program as "positive, easy to follow, and motivating." Conclusion Wearable-guided circadian biofeedback engaged patients with CHF to actively restore physiological rhythms, improving both objective autonomic regulation and perceived recovery. While general behavioral advice enhanced daytime HRV, personalized circadian alignment produced targeted nocturnal gains in parasympathetic activity and sleep quality. These findings highlight circadian biofeedback as a promising patient-centered strategy to strengthen daily resilience and preventive self-management in heart failure.For image description, please refer to the figure legend and surrounding text. For image description, please refer to the figure legend and surrounding text.