The human diving reflex is an innate cardiorespiratory adjustment triggered during apnea that concurrently activates both sympathetic and parasympathetic branches of the autonomic nervous system to maintain physiological stability under stress. Although pupil dilation and constriction are antagonistically regulated by these branches, the effect of the diving reflex on pupil diameter oscillations, known as hippus, remains unexplored. Here, we compared hippus in healthy participants during breathing or apnea either with (Wet) or without (Dry) facial immersion in cold water. In both apneic conditions, hippus exhibited reduced power in the low-frequency band (< 0.25 Hz). Notably, during Wet apnea, we observed a reallocation of power towards higher frequencies (> 0.25 Hz) and increased entropy of fluctuations, indicating a shift in autonomic balance and greater signal complexity during the diving reflex. This pilot study highlights pupil dynamics as a sensitive and non-invasive probe of autonomic adjustments underlying the human diving reflex.

Mesotherapy is an evidence-based, minimally invasive technique used across multiple clinical fields, including pain medicine, sports medicine, rehabilitation, vascular diseases, dermatology, and aesthetic medicine. In recent years, international consensus recommendations have been developed to guide its safe and standardized application. To identify essential criteria for good clinical practice in mesotherapy and to promote their adoption among healthcare professionals and health authorities through a secondary analysis of the current recommendations issued by the Italian Society of Mesotherapy. A multidisciplinary panel of experts reviewed existing evidence-based recommendations and related scientific literature through a structured Delphi process. The analysis aimed to identify key elements that ensure safety, efficacy, and consistency in mesotherapy practice, and to distinguish evidence-supported interventions from outdated or inappropriate procedures. The expert panel formulated 49 evidence-based recommendations covering terminology, clinical use, and ethical aspects. Recommendations reached a high level of agreement (92.6%), confirming the robustness and clinical relevance of mesotherapy. The resulting standards clearly define what should and should not be done in modern mesotherapy practice. Adherence to evidence-based recommendations promotes transparency, patient safety, and professional accountability, while supporting regulatory recognition of mesotherapy as a scientifically grounded therapeutic option. These guidelines provide a framework for standardizing clinical practice, guiding education and research, and ensuring appropriate integration of mesotherapy into individualized treatment pathways. These evidence-based recommendations support harmonization of mesotherapy practice and its recognition by health authorities.

Background: Military deep divers experience extreme environmental stressors, particularly with prolonged diving. Alterations such as hyperbaric conditions and variable O ₂ levels can prompt systemic/local oxidative stress (OxS) and elevated nitric oxide (NO ^. ) post-dive release, heightening the risk of inflammation and cardiovascular events. Yet, deep diving (e.g. saturation diving) can also lead to cognitive impairment, whose mechanisms remain largely elusive but relevant to determine. Methods: Three Deep Divers (Italian Navy-Comsubin), with an average age of 31.00 ± 2.64 years, carried out a technical surface-supplied bounce diving in open water (-89m) in the Mediterranean Sea. From them, we collected saliva and urine samples before diving (T0), after deep diving followed by water-surface decompression (T1), and after complete subemersion (T2). To assess for pro-inflammatory and stress conditions, we evaluated reactive oxygen species (ROS) production, DNA oxidation (8-OHdG), total antioxidant capacity (TAC), nitric oxide (NO ^. ) oxidation products, and the levels of interleukin-6, cortisol, brain-derived neurotrophic factor (BDNF), dopamine, and glutamate. Results: At T1, ROS production increased (+ 121%) and continued to increase just to T2, coupled to a continuous rise in 8-OHdG, and a contemporary decline in TAC. Simultaneously, cortisol levels increased while those of dopamine decreased (-27%). BDNF levels were also sizably elevated (+ 175%). Conversely, no changes in pro-inflammatory markers and NO concentrations were evident. Conclusions: Oxidative stress and neurotransmitter increase and/or decrease (according to biomarkers evaluated) occur post-deep diving, suggesting preventative strategies to mitigate cognitive impairment.

Background/Objectives: Heart rate variability (HRV) analysis is a valuable noninvasive tool to evaluate autonomic nervous system activity, especially under environmental stress. Diving, which combines immersion, hyperbaric exposure, and altered respiratory gas dynamics, presents a unique physiological challenge. This single-subject case study aimed to assess autonomic modulation during and after a closed-circuit rebreather (CCR) dive using comprehensive HRV analysis. Methods: A healthy male diver underwent continuous RR interval monitoring before, during, and after a CCR dive using the MCM100 military device. HRV parameters were evaluated across time-domain, frequency-domain, and nonlinear domains. Data processing was performed using the Kubios software, and statistical comparison between phases were carried out using paired-sample tests in SPSS. Results: During the dive, HRV indices showed a significant decrease in RMSSD (p < 0.01), SDNN (p < 0.05), and SD1 (p < 0.01) compared to the baseline, indicating marked parasympathetic withdrawal. A concurrent increase in the LF/HF ratio (p < 0.05) suggested sympathetic predominance. In the post-dive phase, parasympathetic indices such as RMSSD and SD1 improved relative to the dive phase (p < 0.05) but remained below baseline. Nonlinear measures, including SD2/SD1 ratio and sample entropy, also varied significantly across phases. Conclusions: This case study demonstrates significant autonomic shift associated with a CCR dive, characterized by acute parasympathetic withdrawal and a partial recovery post-dive. HRV profiling may offer a sensitive, noninvasive approach for monitoring stress and recovery dynamics in professional divers.