Effect of Short-Term Sunlight Exposure on Blood Pressure and Pulse Rate in Vitamin D₃-Insufficient, Prehypertensive Patients: A Pilot Study

Abstract

<b><i>Introduction:</i></b> This study was conducted to evaluate the effect of short-term sunlight exposure on blood pressure (BP) and pulse rate (PR) in vitamin D<sub>3</sub>-insufficient, prehypertensive patients. <b><i>Methods:</i></b> Twenty prehypertensive male participants were prospectively enrolled in this pilot study. BP and PR were measured using 24-hour ambulatory BP monitoring and endocrine biomarkers were assessed. <b><i>Results:</i></b> Sunlight exposure decreased 24-hour systolic BP (SBP), diastolic BP (DBP), and PR (SBP: 132.6 mm Hg to 129.3 mm Hg, DBP: 77.6 mm Hg to 75.7 mm Hg, and PR: 76.1 bpm to 71.3 bpm, <i>p</i> values: 0.0011, 0.0012, and <0.0001, respectively). The decrement patterns of SBP, DBP, and PR during nighttime (SBP: 123.5 mm Hg to 117.9 mm Hg, DBP: 72.2 mm Hg to 68.0 mm Hg, and PR: 68.2 bpm to 59.1 bpm, <i>p</i> values: 0.0015, 0.0003, and <0.0001, respectively) were more profound compared between daytime and nighttime. Blood levels of 25-hydroxyvitamin D<sub>3</sub> were significantly increased (<i>p</i> = 0.0001) but aldosterone levels were significantly decreased (<i>p</i> = 0.0014) after sunlight exposure. In addition, an inverse relationship between 25-hydroxyvitamin D<sub>3</sub> and aldosterone levels was observed (<i>R</i> = –0.4709, <i>p</i> = 0.0419). <b><i>Discussion/Conclusion:</i></b> The pilot study gives promising results that it is worthwhile to evaluate short-term sunlight exposure as a potentially effective approach in decreasing BP and PR in 25-hydroxyvitamin D<sub>3</sub>-insufficient prehypertensive patients in a larger trial with a control group.