World Hypertension Day is observed every year on May 17 to highlight the importance of monitoring blood pressure, and educate the world that about one billion people are living with high blood pressure, or hypertension, globally. When a person's systolic blood pressure, or the pressure in the arteries when the heart beats, is consistently above 140 mm Hg, and/or the diastolic blood pressure, or the pressure in the arteries when the heart rests between beats, is consistently above 90 mm Hg, they are said to have hypertension.


A blood pressure level less than 120/80 mm Hg is said to be normal.


Hypertension alone may not cause any symptoms, but it is the number one risk factor for heart disease, stroke, renal complications and premature death. Some people with hypertension may experience symptoms such as headaches, shortness of breath or nosebleeds. 


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Why hypertension patients experience exacerbated symptoms during cold weather


Hypertension patients often experience exacerbated symptoms during cold weather. Also, cold weather increases the incidence of hypertension-associated diseases such as stroke and myocardial infarction, or heart attack, caused by decreased or complete cessation of blood flow to a portion of the muscles of the heart, according to the United States' National Institutes of Health (NIH).   


Blood pressure is usually higher in the winter and lower in the summer because low temperatures cause blood vessels to temporarily narrow, which increases blood pressure as more pressure is required to force blood through narrowed arteries, according to Mayo Clinic. 


This phenomenon is called vasoconstriction.


“Cold weather tends to raise hypertension primarily through a process named vasoconstriction. Vasoconstriction is a process that is used by the body to keep the extremities warm,” Dr Aruna Kalra, Senior Gynaecologist and Obstetrician, CK Birla Hospital, Gurugram, told ABP Live.


An extremity refers to a limb, such as an arm or leg.


“When exposed to low temperatures, blood vessels in the hands and legs become smaller in diameter, which increases the force with which blood is pumped. The reduced sweating in winter causes sodium and blood volume retention, which contributes to the increase in blood pressure,” Dr Kalra explained.


In order to conserve body heat during cold weather, all arteries constrict, resulting in increased resistance to flow of blood within those blood vessels. As a result, the heart beats with greater force than normal, causing the blood pressure to increase.


“During cold weather the arteries of the whole body constrict to conserve heat. This increases the resistance to the blood flow in these arteries. So, the heart has to beat more forcefully, hence increasing BP and exacerbating symptoms,” Dr Vanita Arora, Interventional Cardiologist, Apollo Hospital, told ABP Live.


The elderly and patients with heart disease are particularly vulnerable to these alterations in the diameter of blood vessels, which is concerning because a sharp increase in blood pressure can induce angina, a type of chest pain caused by reduced blood flow to the heart; heart attacks, or strokes, Dr Kalra said. Persistent blood pressure spikes can affect the kidneys too.


Dr Kalra also said that an increase in blood pressure may be caused by winter weight gain and a lack of exercise. 


Therefore, it is important to maintain body weight during the winter season, and exercise regularly to ensure that body heat is conserved, and blood vessels will not have to undergo vasoconstriction to preserve heat. This will help keep one’s blood pressure normal, or will prevent the exacerbation of symptoms in hypertension patients.


Leading an unhealthy lifestyle, consuming processed foods, not exercising regularly, and experiencing excess stress can cause hypertension. Diabetes and obesity are some of the risk factors which increase the chances of having hypertension. 


Hypertension can seriously impact one's heart, brain, kidneys and eyes, but through proper measures, the condition can be managed.


Avoiding smoking, exercising for at least 30 minutes every day, consuming a healthy diet, limiting sodium and alcohol, maintaining a healthy weight, and managing stress can help prevent hypertension, or manage the condition.