Effects of winter sea bathing on psychoneuroendocrinoimmunological parameters

Context: Many people claim winter sea bathing gives them energy and health. According to the psychoneuroendocrinoimmunology (PNEI) paradigm, the stress response elicited by cold water immersion could indeed induce several beneficial psychophysical alterations. Objective: To determine the effects of winter sea bathing on psychological wellbeing, stress and immune markers. Design: A cross-sectional study. Participants: 228 people, between 19 and 88 years, including 107 winter sea bathers and 121 controls. Main Outcome Measures: A battery of questionnaires was administered to assess sociodemographic characteristics, self-perception of mental and physical heath, the number, duration and intensity of Upper Respiratory Tract Infections (URTIs) in the last year, and Big Five personality traits. 17 winter sea bathers and 15 controls (mean age 67 years) were further examined to evaluate physiological health, underwent one ear-nose-throat (ENT) examination, and provided saliva samples for measurements of biological markers (cortisol, sIgA, IL-1β, IL-6). Results: Winter sea bathing was associated with lower levels of self-reported stress and higher wellbeing. The ENT examinations did not reveal signs of URTIs in winter sea bathers, who exhibited significantly higher levels of salivary sIgA compared to controls. Neither salivary IL-1β nor cortisol levels were significantly different between the two groups. Conclusions: Winter sea bathers (even the elderly) had a perception of higher wellbeing and reported better health: thus, they appeared to take advantage of potential distress (cold water exposure) to improve their health.