Seasonal variation of blood pressure in young normotensive

In this study, the variation of blood pressure in young normotensive medical students has been recorded in winter and summer. Daytime blood pressure of young normotensive medical students has been measured in supine position. It has been found that both the systolic and diastolic pressure increases in low ambient temperature. It may be due to sympathetic stimulation and increase secretion of catecholamines in response to cold. Both sympathetic stimulation and catecholamines causes vasoconstriction leading to increased peripheral resistance and thereby increases diastolic pressure. At the same time the above mention stimuli increases heart rate and force of contraction of cardiac muscle causing increased cardiac output and thereby increases the systolic pressure.