Study on identification of insomnia syndrome based on pulse diagnosis and heart rate variability

Kai Yin^1,*

¹ School of Acupuncture and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, 250355, China

*Correspondence author: Kai Yin at School of Acupuncture and Tuina, Shandong University of Traditional Chinese Medicine, 4655 Daxue Road, Changqing District, Jinan, Shandong Province, 250355, China. Email: xiangminnihao@126.com.

KEYWORDS Insomnia, Heart Rate Variability (HRV), Pulse Diagnosis, Syndrome Differentiation

ABSTRACT Background: As a prevalent functional sleep disorder closely associated with human quality of life and frequently co-occurring with chronic diseases, insomnia has been extensively studied in modern medicine through neuroendocrine systems and autonomic regulation approaches. Traditional Chinese Medicine (TCM) emphasizes pulse diagnosis and syndrome differentiation. Heart Rate Variability (HRV), as an objective indicator of autonomic nervous system function, shares intrinsic connections with TCM pulse patterns. This retrospective study investigates the feasibility and current research status of integrating HRV analysis with pulse diagnosis for identifying insomnia syndromes, providing insights to objectively validate TCM syndrome differentiation.Method: Literature on “HRV”, “pulse diagnosis”, and “insomnia” was systematically retrieved from databases including PubMed, Web of Science, and CNKI. The search period covered from database establishment to December 31,2024, with inclusion criteria requiring: diagnosis of insomnia, HRV measurement, pulse analysis, and TCM syndrome differentiation. A total of 27 observational studies and 8 interventional studies were included. The study summarized sample characteristics, HRV parameters, pulse patterns, and intervention outcomes respectively.Observational studies have revealed distinct HRV and pulse pattern changes across TCM syndromes: Liver Qi Stagnation with Fire Transformation (LF/HF↑) and Stringy Pulse (xianmai↑) in the Liver-Heat Syndrome type, while Heart-Spleen Deficiency (RMSSD↓) and Fine Weak Pulse (xixiaomai↑) are observed in the Heart-Spleen Deficiency type. Interventional research demonstrates that Traditional Chinese Medicine (TCM), acupuncture, and cognitive behavioral therapy (CBT) can effectively improve HRV parameters including increased high-frequency components (HF), reduced low-frequency components (LF/HF), as well as the slippery, slow, and harmonious pulse patterns alongside sleep quality enhancement. The synchronized improvement in both HRV and pulse patterns holds clinical significance for evaluation and dynamic monitoring.Conclusion: The integration of HRV and pulse diagnosis provides comprehensive physiological, biochemical, and quantitative indicators for evaluating insomnia syndromes and treatment efficacy. This study demonstrates that HRV can serve as a breakthrough point to achieve quantification and standardization in pulse diagnosis. Future research should focus on developing high-quality, standardized methodologies, leveraging AI and wearable devices to explore diagnostic technologies. These advancements will facilitate integrated TCM-Western medicine consultations, syndrome differentiation, and personalized treatment approaches for insomnia management, ultimately advancing the modernization of traditional Chinese medicine.

INTRODUCTION

Insomnia has become the most prevalent sleep disorder in modern society, with its prevalence rate rising annually and emerging as a global public health concern [1,2]. The accelerating pace of life, increasing stress levels, and the proliferation of electronic devices have made insomnia a “new companion” in people’s daily routines. Studies indicate that approximately 20%-40% of adults suffer from insomnia, with higher incidence rates observed among women, the elderly, and individuals experiencing significant psychological stress [3]. Chronic insomnia profoundly impacts patients’ daily efficiency, work performance, physical/mental well-being, and social functioning, while also correlating with various conditions including anxiety disorders, depression, cardiovascular diseases, diabetes, and immune dysfunction [4]. Beyond the subjective experience of “difficulty falling asleep” or “poor sleep quality,” insomnia primarily manifests through subtle physiological effects on the body. Recent research increasingly emphasizes its impact on autonomic nervous system function, which may serve as a key pathway for insomnia-induced complications [5].

According to international consensus, insomnia disorder refers to persistent disturbances in sleep duration, frequency, and quality, specifically manifested as difficulty falling asleep, trouble maintaining sleep, and frequent awakenings, accompanied by daytime functional impairments. The diagnosis primarily relies on the “International Classification of Sleep Disorders, Third Edition (ICSD-3)” and the “Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)”. The former requires symptoms persisting for at least three months, occurring at least three times weekly, and affecting social, occupational, or other significant functional aspects. The latter provides additional clinical psychological considerations, emphasizing the need to exclude other mental disorders or physical conditions [6-8]. While current diagnostic criteria have established clear and unified standards, the understanding of its pathogenic mechanisms and population variations remains incomplete. Particularly regarding early clinical classifications, disease subtypes, and responses to interventions, traditional diagnostic approaches still exhibit limitations such as subjectivity and individual variability [9].

In classical Chinese medicine, insomnia falls under the category of “Bu Mei” (insomnia), which is believed to be fundamentally related to organ functions, primarily involving the heart, liver, spleen, and kidneys. Common patterns include spleen-kidney deficiency, liver fire stagnation, yin deficiency with hyperactivity of fire, and phlegm-heat disturbing the heart [10]. TCM diagnosis employs “pattern differentiation and treatment” (bianzheng lüzheng), with pulse diagnosis serving as a crucial foundation for pattern identification. By analyzing pulse characteristics such as deficiency-excess patterns, urgency-relaxation ratios, smoothness-dryness, and wiriness-thinness, the finger pulse becomes the key element in pulse diagnosis. This serves as the basis for physicians to assess qi-blood vitality and pathological changes in organs after pulse examination [11]. Traditional pulse diagnosis, however, relies heavily on clinical experience and subjective assumptions without standardized quantification, leading to diagnostic discrepancies among practitioners. Improving the objectivity and standardization of pulse diagnosis remains a critical challenge in modern TCM practice [12]. With advancements in bio-signaling technology, HeartRateVariability (HRV) – a biomarker reflecting autonomic nervous system activity – has gained increasing application in sleep diagnosis [13]. HRV detects sympathetic and parasympathetic nervous tension through R-R interval variations in ECG or pulse wave analysis. Insomnia patients exhibit heightened sympathetic tension and reduced parasympathetic activity, with HRV indices showing significantly lower SDNN, RMSSD, and HF values while LF/HF ratio increases markedly. These findings establish HRV as a reliable neurophysiological indicator for insomnia patients, supported by its objective assessment, high repeatability, and convenience compared to traditional subjective questionnaires or empirical diagnoses [14,15].

Recent studies have integrated Traditional Chinese Medicine (TCM) pulse diagnosis with heart rate variability (HRV) for disease classification. Multiple studies have demonstrated correlations between pulse patterns and HRV parameters, such as increased LF components in wiry pulses and reduced SDNN in thready-rapid pulses, suggesting that HRV and pulse patterns reflect the same physiological process [16]. Some researchers have developed predictive models combining HRV analysis with TCM pulse readings to enhance syndrome diagnosis accuracy, particularly for complex conditions like insomnia characterized by multifactorial etiology and subjective symptoms [17]. However, most existing reviews either focus on HRV applications in insomnia or emphasize the evolution of pulse diagnosis techniques. Few comprehensive analyses have systematically evaluated the current status, advantages, limitations, and future prospects of combined pulse-HRV approaches in insomnia management.

This study aims to conduct a systematic review on the theme of “Insomnia Syndrome Identification Based on Pulse Diagnosis and HRV” as a comprehensive review topic. It systematically analyzes observational and intervention studies from recent Chinese and English literature, examining the differences in HRV pulse integration for insomnia patients across various study designs. The research evaluates the value of this integrated approach in TCM syndrome identification, explores the combined physiological mechanisms and models, while identifying existing issues and potential improvements. These findings provide theoretical foundations and research perspectives for objectively characterizing TCM syndromes, understanding insomnia mechanisms, and developing integrated TCM-Western medicine diagnostic and therapeutic strategies.

METHODOLOGY

Retrieval strategy

This study employed a systematic literature search method to review recent analyses combining pulse diagnosis and heart rate variability (HRV) in insomnia patients. The search was conducted across PubMed, Web of Science, CNKI (China National Knowledge Infrastructure), and Wanfang Database, with no time limit imposed to ensure comprehensive coverage. For English literature, we combined MeSH terms and keywords using Boolean logic (AND/OR). Chinese search terms included “insomnia”, “pulse diagnosis”, “heart rate variability”, “cerebral diagnosis”, “autonomic nervous system”, “sympathetic”, “parasympathetic”, and “syndrome differentiation”. Adjustments were made to the search strategy based on database-specific rules. To ensure completeness, relevance, and retrospective verification of initial inclusion criteria, we supplemented missing literature by limiting both Chinese/English searches and review backgrounds. Ultimately, only original primary studies were included in the analysis.

Research selection

This review screened retrieved literature using predefined inclusion and exclusion criteria. Inclusion criteria included: (1) Participants were patients with confirmed insomnia diagnosed according to authoritative standards such as the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) or International Classification of Mental Disorders (ICSD-3); (2) Studies employed heart rate variability (HRV) metrics for autonomic nervous function assessment or utilized traditional Chinese medicine pulse diagnosis instruments to collect and analyze pulse characteristics; (3) Study designs were observational studies (cross-sectional, case-control, cohort studies) or intervention studies (e.g., HRV and pulse changes following TCM herbal medicine, acupuncture, or behavioral therapy interventions); (4) Provided comparative data between insomnia groups and healthy control groups, or analyzed pre-and post-intervention differences.

Exclusion criteria: (1) Non-original studies, such as conference reports, reviews, or case analyses; (2) Studies without submitted HRV or pulse diagnosis quantitative data; (3) Studies with small sample sizes (n<10) or inappropriate statistical methods; (4) Patients with comorbid serious conditions (e.g., psychiatric disorders, epilepsy) or uncertain intervention measures. All literature was initially screened by two researchers through title and abstract review. Qualified articles were then read in full for evaluation. Disagreements were resolved through third-party mediation to determine inclusion. Included literature underwent data extraction and organization.

Physiological correlation between heart rate variability analysis index and pulse characteristics

At present, the application of heart rate variability (HRV) in the medical field is mostly used in the analysis of autonomic nervous function, especially in the physiological indicators of mental and psychological conditions such as insomnia, anxiety and depression. HRV is an indicator reflecting the balance between sympathetic and parasympathetic nerves, which is related to the characteristics of sleep quality.

Meanwhile, Traditional Chinese Medicine (TCM) pulse diagnosis emphasizes evaluating organ functions, qi-blood dynamics, and disease progression through pulse characteristics including thinness, stringiness, slowness, slippery texture, and deficiency. Studies have explored the correlation between heart rate variability (HRV) and pulse patterns, proposing that HRV—referred to as the “digital pulse” in TCM—can reflect the circulation of vital energy, qi, and blood to some extent. Below is a partial comparison of commonly used HRV time-domain and frequency-domain indicators with typical pulse pattern.

Table 1. Common HRV Indicators, Physiological Interpretations, and Their Possible Correspondence to TCM Pulse Characteristics

SDNN (Standard Deviation of NN Intervals) refers to the standard deviation of normal RR intervals within a specific time frame, serving as one of the core indicators reflecting overall HRV levels [30]. During normal sleep, the autonomic nervous system exhibits circadian rhythm fluctuations with parasympathetic dominance, resulting in higher SDNN levels. In insomnia patients, SDNN often shows significant reduction, indicating restricted heart rate rhythm fluctuations and decreased autonomic nervous system activity. In traditional Chinese medicine pulse diagnosis, elevated SDNN corresponds to “slippery pulse” and “slow pulse,” typically indicating “harmonized qi-blood” and “coordinated organ functions,” commonly observed in well-rested individuals. Conversely, reduced SDNN is often manifested as “fine pulse” or “stringy pulse,” suggesting qi-blood deficiency or liver qi stagnation, frequently seen in insomnia patterns characterized by heart-spleen deficiency or liver stagnation transforming into fire.

The Root Mean Square Difference (RMSD) measures the root mean square of adjacent RR intervals, controlled by the vagus nerve and reflecting parasympathetic activity. In insomnia patients—particularly those with moderate to severe sleep disorders—the RMSD often decreases. This may be linked to persistent emotional tension and anxiety suppressing vagus nerve function. The reduction in RMSD is frequently associated with “counting pulse” patterns, commonly observed in “yin deficiency with fire excess” type insomnia characterized by irritability, dry mouth, and heat sensation in the palms, soles, and chest. Conversely, elevated RMSD values typically present with “slowed” and “harmonious” pulse patterns dominated by parasympathetic activity, predominantly seen in individuals with stable sleep patterns [31,32].

The pNN50 index, defined as the proportion of continuous RR intervals exceeding 50ms, serves as a parasympathetic dominance indicator. This parameter reflects heightened sensitivity to short-term autonomic activity. Insomnia patients exhibit significantly lower pNN50 values than healthy individuals, indicating reduced responsiveness to stimuli and psychosomatic imbalance. In pulse diagnosis, decreased pNN50 corresponds to “sinking-thin” or “weak” pulses, suggesting qi-yin deficiency (deficiency of qi and yin) or yin’s inability to restrain yang. Conversely, elevated pNN50 manifests as “slipping” or “soft” pulses, reflecting mental clarity and smooth qi circulation. This distinction proves particularly significant in differentiating between heart-spleen deficiency syndrome and yin deficiency with hyperactivity of fire [33,34].

The low-frequency (LFfrequency,0.04–0.15Hz) segment is composed of sympathetic and partial parasympathetic nerves. LF levels determine breathing, blood pressure, and mood. Elevated LF is associated with sympathetic nervous system activity in patients with insomnia subtypes characterized by “difficulty falling asleep” and “early awakening” [35]. Increased LF correlates with “stringy pulse” and “tight pulse,” which reflect liver qi-blood stagnation and hyperactivity of liver yang, commonly seen in insomnia with frequent dreaming due to liver depression-fire syndrome. Decreased LF is linked to “slow pulse” and “delayed pulse,” typically observed in cold-induced blood deficiency and yang deficiency patterns of insomnia. As a composite indicator, LF should be interpreted alongside HF and LF/HF ratios [36].

The High Frequency (HF, 0.15-0.4 Hz) band directly reflects parasympathetic nerve activity, particularly related to respiration. During sleep, HF activity typically increases, facilitating relaxation and sleep onset [37]. However, in insomnia patients—especially those with anxiety or heart-kidney disharmony patterns—HF levels often decrease, indicating parasympathetic inhibition and failure to achieve relaxation. Patients with reduced HF frequently exhibit “thin and rapid” or “weak” pulse characteristics, clinically manifesting as fatigue, memory impairment, and anxiety, suggesting qi-yin deficiency or yin deficiency with hyperactivity of fire. Conversely, elevated HF is associated with “soft” or “sluggish” pulses, indicating effective autonomic nervous system regulation. These HF variations provide quantitative evidence for distinguishing between “deficiency agitation” and “excessive heat” types of insomnia [38].

LF/HF serves as a sensitive indicator reflecting the balance between sympathetic and parasympathetic nervous system functions. The normal range for LF/HF is 0.5-2.0, with abnormal values indicating dominance of a particular nervous system. Insomnia patients exhibit increased LF/HF levels, demonstrating enhanced sympathetic activity and reduced parasympathetic function – a key physiological basis for nighttime “hyperexcitability” [39]. In traditional Chinese medicine (TCM), elevated LF/HF is associated with pulse characteristics like “stringy-thready” or “fine-tender,” commonly seen in conditions such as liver fire disturbing the heart and yin deficiency with internal heat. Conversely, decreased LF/HF typically presents as “slow,”  “delayed,” or “sluggish” pulses, accompanied by mental calmness and improved sleep quality. Objectively, this provides a physical basis for evaluating the balance between “deficiency-excess” and “cold-heat” states [40].

Figure 1 Schematic diagram of screening process for studies included in the system review

RESULTS

Studies reviewed

Based on the aforementioned search strategy and literature selection procedures (as shown in Figure 1), this study identified 1,395 database entries. After supplementing with three additional sources and removing duplicates, 539 articles were selected for title and abstract screening. Following preliminary screening, 436 papers were excluded due to mismatched themes, leaving 69 articles for full-text evaluation.

During the literature review, 34 studies were excluded due to missing HRV or pulse diagnosis data, unclear study subjects, or ambiguous interventions. Ultimately, 35 studies met the criteria for this systematic review, including: 27 observational studies (primarily cross-sectional, case-control, and prospective cohort studies) focusing on HRV characteristics, pulse pattern distribution, and their correlations in insomnia patients – providing substantial evidence for the fundamental relationship between HRV and traditional Chinese medicine pulse patterns. Additionally, 9 intervention studies evaluated HRV metrics and pulse characteristics through TCM interventions (including herbal therapies, acupuncture, and cognitive behavioral therapy), tracked post-treatment symptom changes, and analyzed HRV trends, offering empirical support for combined pulse-diagnosis and HRV indicator interventions.

The research encompasses a wide range of spatiotemporal distributions and involves numerous domestic and international research groups. The subjects involved all meet the insomnia diagnostic criteria of ICSD-3 or DSM-5, demonstrating broad representativeness and high comparability. In summary, this study continuously explores and focuses on the relationship between “pulse diagnosis-HRV-symptom patterns” in terms of both quantity and type, providing a solid foundation for subsequent model construction and mechanism interpretation.

Observational studies

Table 2 Characteristics of the 27 observational studies

As shown in Table 2, the 27 observational studies encompassed diverse populations including different genders and groups of insomnia patients, categorized by diagnostic groups (DSM-5, ICSD-3, Chinese Classification of Mental Disorders). Most utilized multimodal physiological observations such as ECG, pulse diagnosis, or manual pulse diagnosis to obtain HRV data. Time-domain parameters like SDNN and RMSSD, along with frequency-domain parameters such as LF/HF, were predominantly employed for HRV analysis. These findings were correlated with TCM syndromes including liver stagnation, yin deficiency, and dual deficiency of heart-spleen syndrome. Some studies further validated these conclusions using polysomnography (PSG) to assess sleep efficiency. Overall, the application of HRV combined with TCM pulse diagnosis in identifying insomnia syndromes demonstrates relatively robust evidence, providing a solid data foundation for developing intelligent syndrome differentiation models in future research.

Interventional studies

Table 3 Characteristics of the 8 interventional studies

Table 3 summarizes the characteristics of eight studies employing different intervention methods: Traditional Chinese Medicine (TCM), acupuncture, auricular acupressure, moxibustion, tuina massage, cognitive behavioral therapy, and integrated TCM-Western medicine. Most interventions lasted 2-6 weeks with daily to weekly frequency. Post-intervention reports showed significant improvements in heart rate variability (HRV), reduced RMSSD and SDNN, decreased LF/HF ratio, enhanced parasympathetic activity, alleviated sympathetic tension, and a pulse transition from wiry, thin, and weak to gentle, smooth, and harmonious—trends consistent with HRV patterns. Sleep quality improvements were evident through reduced PSQI and ISI scores, with some studies validating these findings using polysomnography (PSG) or sleep diaries. These findings suggest that multiple interventions targeting autonomic nervous system regulation and pulse diagnosis can effectively improve insomnia symptoms, with HRV combined pulse diagnosis serving as a reliable objective indicator for evaluating treatment efficacy and symptom resolution.

Research on Traditional Chinese Medicine intervention and HRV/pulse improvement

Table 4. Changes in Pulse Characteristics of Insomnia Patients After Chinese Herbal Intervention

As a classic formula in Traditional Chinese Medicine (TCM) for treating insomnia, herbal medicine is characterized by its holistic approach and syndrome differentiation, which constitute the two core principles of TCM interventions for insomnia. With the deepening exploration of TCM modernization, researchers have increasingly focused on how herbal interventions affect patients ‘autonomic functions and TCM pulse patterns. Initial studies have examined these interventions’ efficacy through both objective physiological indicators and traditional pulse pattern evolution analysis.

In 5 intervention studies, the subjects were intervened with TCM syndrome differentiation, which was clearly defined as heart and spleen deficiency, liver fire transforming fire, heart-kidney disconnection, blood deficiency, etc. The intervention methods were modified addition method, oral method, etc., and the intervention time ranged from two to four weeks. Some interventions were combined with other methods, such as ear acupoint massage and sleep education. See Table 4.

From the perspective of pulse pattern changes, most patients exhibited “fine”, “weak”, “taut”, and “slippery” pulse characteristics before TCM intervention. Patients with heart-spleen deficiency often showed “fine” and “weak” pulses, indicating qi deficiency and mental restlessness; those with liver stagnation typically presented “taut” pulses reflecting liver qi stagnation; while patients with heart-kidney disharmony frequently displayed “thin and rapid” or “weak and slippery” pulses, suggesting yin deficiency with hyperactivity of fire [41,43]. Post-intervention, most patients exhibited normal “harmonious” pulse patterns such as “slow”, “slippery”, and “moderate and strong”, demonstrating TCM’s ability to regulate qi and blood circulation and harmonize organ functions. The traditional interpretation of pulse pattern changes serves as diagnostic feedback for TCM interventions. This trend aligns with HRV data. Post-treatment, parasympathetic indicators like RMSSD, pNN50, and HF increased while LF/HF decreased, indicating a shift from sympathetic dominance to parasympathetic regulation during nighttime, thereby improving sleep quality [44-46]. For instance, one study using sour jujube seed decoction combined with psychological counseling for heart-spleen deficiency insomnia showed significantly elevated RMSSD after 4 weeks, accompanied by pulse transformation from “fine and weak” to “moderate and relaxed”. Another study employing phlegm-resolving and sedative herbal granules for phlegm-heat disturbing heart insomnia revealed markedly reduced LF/HF post-treatment, along with pulse transition from “slippery and rapid” to “slippery and moderate”, suggesting the efficacy of reducing sympathetic tension correlates with clinical outcomes. Regarding sleep quality assessment, the included studies utilized sleep questionnaires such as the PSQ and ISI to evaluate sleep patterns before and after interventions. Most research demonstrated significant improvements in subjective sleep quality, sleep latency, and nighttime awakenings. Some studies employed polysomnography (PSG) or sleep diaries to monitor sleep outcomes [47,48]. The enhancements in heart rate variability (HRV), pulse patterns, and sleep quality scores suggest that traditional Chinese medicine interventions not only affect sleep behavior but, more importantly, may influence the coordination of neuro-humoral-fuji system interactions through regulation of the psychosomatic system [49,50].

Traditional Chinese medicine (TCM) interventions demonstrate clear clinical efficacy in treating insomnia. By regulating autonomic nervous system function, these therapies enhance heart rate variability (HRV) and facilitate the transition of pulse patterns from pathological to physiological states, providing modern quantitative support for TCM’s “preventive treatment” philosophy [51]. The coordinated changes in HRV and pulse patterns before and after intervention further validate the traditional theories that “the pulse reflects the sea of blood and qi” and “spiritual energy is internally stored while manifesting externally through the pulse” as having verifiable connections with modern physiological mechanisms [52]. Future research could establish dynamic efficacy evaluation models through larger-scale, double-blind randomized controlled trials integrated with smart wearable devices and digital pulse diagnosis systems, thereby advancing the objective study of TCM syndromes to deeper levels.

Effects of cognitive behavioral therapy on HRV and pulse

Table 5 Pulse Characteristics of Insomnia Patients After CBT-I Intervention

Cognitive Behavioral Therapy for Insomnia (CBT-I) is recognized as the gold standard non-pharmacological intervention internationally, serving as the first-line treatment for chronic insomnia with strong evidence-based support [53-56]. This therapy works by modifying patients ‘sleep attitudes, improving unhealthy sleep behaviors, restoring healthy sleep patterns, and enhancing both sleep quality and daytime functioning. Recent studies have explored CBT-I’s effects on autonomic nervous systems (hypothalamic regulation, HRV) and Traditional Chinese Medicine meridians, aiming to uncover the physiological mechanisms underlying psychological interventions in psychosomatic regulation [57-59].

As shown in Table 5, four studies were conducted where patients received 4-6 weeks of additional intervention for insomnia on top of conventional CBT-I. After TCM syndrome differentiation, most subjects exhibited patterns such as Yin deficiency with hyperactivity, dual deficiency of heart and spleen, liver qi stagnation, and heart-gallbladder qi deficiency. “Pre-intervention, subjects typically showed ‘fine’, ‘tender’, ‘stringy’, and ‘dry’ pulses, indicating mental restlessness, qi-blood deficiency, liver qi stagnation, and disharmony. Post-intervention, they mostly exhibited ‘soft’, ‘smooth’, and ‘sluggish’ pulses, reflecting balanced yin-yang constitution and mental equilibrium [60,61].” Regarding HRV indicators, post-CBT-I patients showed significant increases in parasympathetic metrics like SDNN, RMSSD, and HF, while LF/HF decreased, indicating sympathetic dominance in sleep behavior and perception. This aligns with the evolution of pulse patterns from tense, weak, and feeble to gentle, smooth, and strong, demonstrating that CBT-I psychologically adjusts patients ‘sleep behavior perception and physiologically improves central-nervous system-peripheral nerve balance [62,63]. Other studies using monitoring methods (sleep diaries, scales, activity logs) further validated CBT-I’s improvements in nighttime awakenings, sleep latency, and deep sleep duration. Combined with synchronized pulse and HRV enhancements, these findings suggest CBT-I not only addresses psychological factors but also regulates the “consciousness-heart-pulse” system (somatic self-regulation), achieving the dual therapeutic effects of traditional Chinese and Western medicine [64].

As a mature non-drug treatment, CBT-I has the effect of stabilizing sleep improvement and restoring autonomic balance. Its influence on pulse in Traditional Chinese medicine also shows an obvious trend, which provides a research direction based on psychology for the objective and digitalization of pulse.

DISCUSSION

Summary of main results

In summary, this study analyzed results from 27 observational studies and 8 interventional studies, demonstrating that both HRV and TCM pulse diagnosis can effectively diagnose insomnia symptoms with high correlation. Observational TCM research revealed distinct HRV characteristics and pulse patterns across different TCM subtypes: Liver Qi Stagnation (LQZ), Liver Yin Deficiency (LYD), Liver Yang Excess (LX), Middle Deficiency (MC), and Middle Weakness (MW) all exhibited unique features. Specifically, LQZ and LYD subtypes typically present sympathetic nervous system overactivity, characterized by wiry and fine pulse patterns. Interventional TCM studies showed that herbal therapy, acupuncture, and CBTI interventions could improve sleep quality through changes in HRV parameters (e.g., RMSSD increase, HF decrease, LF/HF ratio reduction) and pulse characteristics. The findings suggest significant potential for integrating HRV analysis with TCM pulse diagnosis in both syndrome classification and therapeutic evaluation of insomnia disorders.

The impact of methodological differences

The observational and intervention studies included had great methodological heterogeneity, which made the comparability and interpretability of the research results poor. They mainly focused on HRV measurement methods, pulse diagnosis methods, research methods, intervention control methods, etc.

HRV measurement standards lack uniformity. Some studies record resting ECGs (e.g., 5-minute intervals), while others document entire nighttime sleep HRV. Reference values for both time and frequency metrics vary significantly across studies. Differences in instruments, filtering algorithms, and parameters (pNN50, HF, LF/HF) make cross-comparisons of HRV results challenging. Pulse diagnosis in some studies relies on subjective assessments by TCM practitioners, whereas others use pulse wave diagram recording and quantitative analysis with stronger objectivity. However, the absence of standardized protocols and interpretation systems leads to inconsistent categorization of pulse patterns and HRV outcomes. Variations in observation timing (post-wake-up, pre-sleep, or sleep state) and participant states (awake, sleep, or relaxed) also cause fluctuations in HRV and pulse data. In intervention studies, differences in control groups, blinding methods, and treatment duration further compromise the stability and external validity of intervention outcomes.

Therefore, in the future, it is necessary to further improve HRV data collection, pulse signal collection standardization, research design and other details, and improve the repeatability of HRV-pulse correlation studies.

Limitations

This study only included English literature, which may miss some high-quality Chinese studies, limiting the comprehensive understanding and evaluation of the combined application of TCM pulse diagnosis and HRV in the field of insomnia.

Conclusions and recommendations

This systematic review of recent studies on HRV combined pulse diagnosis for identifying insomnia syndromes reveals differences in HRV levels across TCM syndrome patterns and pulse symptom distributions, with these symptoms also associated with autonomic nervous system function. Interventional research demonstrates that traditional Chinese medicine, acupuncture, and cognitive behavioral therapy collectively improve sleep quality by regulating HRV levels and pulse symptoms, suggesting that HRV and pulse symptoms may serve as reliable indicators for objectively classifying insomnia syndromes and evaluating treatment efficacy. Current studies face challenges in unifying requirements for pulse symptom objectification, HRV measurement tools, and sample heterogeneity, making it difficult to establish objective and universal conclusions. Future efforts should focus on expanding HRV-pulse data collection and analysis through multicenter, large-sample studies with standardized methodologies. Integrating AI intelligence and wearable devices could help develop real-time detection and prognosis prediction models for insomnia syndromes, providing theoretical foundations for integrating traditional Chinese medicine’s “diagnosis and treatment” with modern bioinformatics.

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