Does Weather Affect Blood Pressure?

Assessing the Impact of Climate on Hypertension

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We know that without shelter, the weather can greatly influence both our physical and mental state. But can it affect blood pressure? The answer, interestingly enough, appears to be yes.

A large study involving more than 40,000 people convincingly demonstrated that climate changes have a direct impact on a person's relative blood pressure. What the researcher found was that blood pressure was generally better in the summer and less so in winter regardless of the part of the world, altitude, or climate a person lived.

Fluctuations Related More to Change Than Climate

What the study found was that any changes in blood pressure were not so much related to very low or very high temperatures but rather the degree of fluctuation experienced from high summer to high winter.

For example, people who live in Minnesota experience extreme temperature changes between the seasons. Summer days routinely top 80 degrees, while winter days can drop below zero. However, these fluctuations are considered the same for persons living in Phoenix, where the climate is warmer all year long. In both cases, the variation in seasonal temperatures was considered consistent as they were in all other parts of the world.

Moving From One Climate to Another

In recent years, several smaller studies have provided additional insights. What we have learned is that fluctuations in blood pressure change quickly if one moves from a warmer climate to a colder one and, conversely, more slowly if moving from a colder climate to a warmer one.

So, while from Phoenix to Minnesota can result in a significant change in blood pressure (at least for that first winter), moving in the opposite direction most likely won't.

Nobody is yet certain why this happens. One of the underlying factors may be tied to changes in the blood vessel diameter. Blood vessels invariably shrink when they cool down, so people who spend more time in colder climates have more exposure to weather that can trigger this effect.

Over time, this may contribute to a slight increase in blood pressure. 

Scientists have also suggested that colder climates tend to be darker and that associated changes in Vitamin D production (directly tied to sun exposure) may play a part. Others have suggested that subtle hormone changes caused by shifts in the angle of the sun may have a contributing effect.

What the Research Tells Us

While the research is interesting, it doesn't suggest that persons with a very high blood pressure pack up and move in order to improve their health. Any short-term benefit will likely be lost once your body acclimatizes to your new surroundings. 

It also doesn't suggest that your medication needs to be changed with the approach of a new season. Because hypertension treatment is tailored to your specific blood pressure, seasonal changes will already have been adjusted as you are routinely monitored. As such, it is unlikely you’ll need different doses come the rise of summer or the fall of winter.

Sources:
Hayashi, T,; Ohshige, K.; Sawai A, Yamasue, K,; et al. "Seasonal influence on blood pressure in elderly normotensive subjects." Hypertens Res. 2008; 31(3):569-74.

Morabito, M.; Crisci, A.; Orlandini, S.; et al. "A synoptic approach to weather conditions discloses a relationship with ambulatory blood pressure in hypertensives." Am J Hypertens. 2008; 21(7):748-52.

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