## 3 Results
### Cluster Analysis  
A detailed description of each cluster is presented below, integrating demographic, clinical, and autonomic features based on the data summarized in Table 1:  
* Cluster A--Young women with daytime fatigue and sleepiness, who are overweight, without cardiovascular risk factors: This group represents 18.7% of the sample and is composed predominantly of women (60.9%). It is the youngest cluster (51.5 \(\pm\) 14.2 years), followed by Cluster E, with an intermediate BMI (28.2 \(\pm\) 4.9 kg/m\({}^{2}\)), no history of diabetes, who are non-smokers and without cardiorespiratory disease. It presents the highest level of daytime sleepiness (Epworth score: 11.9 \(\pm\) 6.2). Figure 2: Visualization of patients within each cluster. Generated using Grok 2 (xAI). Regarding HRV, this cluster shows low SDNN (100.57 \(\pm\) 29.84 ms), RMSSD (58.22 \(\pm\) 24.68 ms), and SDANN (78.0 \(\pm\) 37.7 ms) values, indicating predominant nocturnal sympathetic activation. * Cluster B--Elderly women with no daytime symptoms, who are overweight, with ca rdiovascular risk factors: This group also accounts for 18.7% of the patients and includes the oldest individuals (75.4 \(\pm\) 5.8 years). It is characterized by a predominance of women (60.9%) with multiple cardiovascular risk factors, such as hypertension (91.6%) and dyslipidemia (66.6%), but low daytime sleepiness ([PERSON] score: 5.8 \(\pm\) 5.4). Atrial fibrillation is present in 25% of patients. None are smokers. HRV is also diminished (SDNN: 80.52 \(\pm\) 26.79 ms; RMSSD: 62.17 \(\pm\) 32.23 ms), again suggesting enhanced nocturnal sympathetic activity. * Cluster C--Older, but not elderly, asymptomatic men without cardiovascular risk factors: Representing 24.4% of the sample, this cluster consists mainly of men (73.3%) with intermediate age (62.0 \(\pm\) 9.9 years) and the lowest BMI (24.2 kg/m\({}^{2}\)). Patients report no significant fatigue or excessive sleepiness (Epworth score: 4.2 \(\pm\) 3.9) and have the lowest number of syncopal episodes in the past 12 months. HRV parameters (SDNN: 140.93 \(\pm\) 166.27 ms; RMSSD: 88.17 \(\pm\) 68.11 ms) are consistent with a preserved parasympathetic tone. * Cluster D--Elderly obese men with cardiovascular risk factors: This group represents 15.4% of the sample, with a predominance of men (63.2%), and is the only cluster characterized by obesity (BMI: 30.0 \(\pm\) 4.8 kg/m\({}^{2}\)). Patients present with hypertension (73.7%), dyslipidemia (68%), and the highest prevalence of diabetes (36.8%). Nearly half have atrial fibrillation (47.4%), and 26.3% have ischemic heart disease. While most are ex-smokers, they show the highest cumulative tobacco exposure. Together with Cluster B, they report the highest total number of syncopal episodes (10.7 \(\pm\) 13.0). HRV parameters (SDNN: 266.37 \(\pm\) 206.98 ms; RMSSD: 296.89 \(\pm\) 70.73 ms) reflect parasympathetic predominance, though with wide variability. * Cluster E--Young overweight male or female smokers with dyslipidemia, daytime fa tigue, and frequent nocturnal awakenings: This is the largest cluster (28.8%) and the second youngest (52.6 \(\pm\) 11.2 years), with a balanced male-female distribution. A high proportion are current smokers (67.9%), while 32.1% are former smokers. This group shows the highest prevalence of asthma (17.9%), and although they do not present with hypertension or diabetes, 39.3% have dyslipidemia. They report the highest number of syncopal episodes in the last 12 months (5.5 \(\pm\) 7.5). Daytime sleepiness is comparable to Cluster A (Epworth score: 11.7 \(\pm\) 6.1), and sleep quality is the poorest, with more awakenings and marked non-rectorative sleep. HRV indicates marked nocturnal sympathetic activity (SDNN: 102.64 \(\pm\) 50.21 ms; RMSSD: 90.11 \(\pm\) 96.48 ms), with the lowest mean RR interval (893.89 \(\pm\) 136.89 ms) and the highest LF/HF ratio (3.8 \(\pm\) 3.0). To assess the robustness and clinical relevance of the clustering solution, both quantitative metrics and visual evaluation were applied.