Besides the tendency to become less physically active in the winter than in warm, sunny months, there are physiological reasons blood pressure can fluctuate during cold weather.

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High blood pressure causes range from diet and stress to genetics and age, but did you know that cardiovascular disease risk factors also show a seasonal pattern? Blood pressure, triglyceride levels, cholesterol levels, body mass index, and waist circumference tend to fluctuate with the seasons, raising the risk for cardiovascular disease in the winter.[1]

Let’s take a closer look at how winter weather affects blood pressure.

High Blood Pressure Causes in the Winter

Cold temperatures increase blood pressure[2] by causing constriction of blood vessels, decreased sweat output, and increased salt load.[1] Lifestyles also tend to change in the winter; people often become less physically active and don’t exercise as much as they do in the warm, sunny months. Hormones that help control blood pressure, like noradrenaline, also show seasonal variations, and they might play a role in this trend.[2]

The Role of the Sun

Hypertension is associated not just with winter, but also with distance from the equator and exposure to sunlight.[3] This has a dual effect.

• Less exposure to UVB rays. UVB rays promote vitamin D synthesis,[3] so with less sunlight, many people become vitamin D deficient in the darker winter months. Vitamin D deficiency increases the risk of hypertension.[2]
• Less exposure to UVA rays. A study in the Journal of Investigative Dermatology found that UVA reduces blood pressure[3] by causing the release of nitric oxide from storage in the skin. Nitric oxide helps to dilate blood vessels, which lowers blood pressure.

Managing Blood Pressure in the Winter

While we can’t change the weather, we can take precautionary measures to manage our blood pressure in the winter. For one, take advantage of the sun when you get the chance.

While excessive sun can damage your skin (don’t let your skin burn), small doses of sunlight can be very beneficial to your blood pressure and your body as a whole. Also, try to keep yourself warm to prevent cold temperatures from elevating your blood pressure.

[1] Heart. 2014 Oct;100(19):1517-23.

[2] Int J Health Sci (Qassim). 2013 Jun;7(2):210-9.

[3] Invest Dermatol. 2014 Jul;134(7):1839-46.

This article was originally published in 2014 and has been updated.