Does the Weather affect Blood Pressure?

summer sky

Can Seasonal Changes affect Blood Pressure?

When we tend to think of factors which influence our blood pressure on a daily, weekly or even monthly basis, I would be willing to wager that Weather and the Seasons would not be top of mind.

But on closer consideration, given that blood pressure is dynamic and subject to numerous fluctuations throughout the course of day, as the result of factors such as activity, stress levels, type of food and drinks consumed, then why wouldn’t the weather and seasonal changes have some sort of effect on it as well?

I have tended to see a difference in my own blood pressure readings between the winter months and the summer months, and I am curious to know if the seasonal change in temperatures can actually play a role in causing this.

What does the Literature say?

Well, there are definitely studies which support the view that blood pressure measurements can vary according to the season, notably the difference between readings in winter vis-a-vis readings in summer.

In one study conducted by Dr Ross Fletcher of the VA Medical Centre in Washington, the results showed that blood pressure was harder to manage in the colder winter months than during the hotter months of summer.

The study looked at the electronic health records of 443,632 veterans suffering from hypertension at 15 VA hospitals in cities throughout the US over a five year period.

Results showed that people treated in the summer were on average 8% more likely to see their blood pressure come down to healthy levels.  This suggests strongly that there is a correlation between time of year and effect on BP, although not for the reasons I would have expected.

As Lead Researcher, Dr Fletcher, states:

“In all cities, there was a seasonal variation that didn’t seem to be related to outside temperature.  Whether you’re in San Juan, Puerto Rico, or Anchorage, Alaska, every summer it gets better and every winter it gets worse.”

What then causes this difference?

The Researchers believe that the reason why blood pressure seems to drop in the summer may be attributed to –  as Dr Fletcher comments:

“People gain weight in the winter and lose weight in the summer. (And) People tend to exercise more in the summer and less in the winter,” 

Consequently, with weight gain and decreased activity level due to the colder weather and less daylight hours during the winter months, blood pressure is more likely to rise.

This may well be one reason for the difference, however I wasn’t convinced that this was the only reason.  It seemed to me that somehow surely there had to be a connection between the actual temperature variations of summer versus winter and the fluctuations in blood pressure.

After some further digging around this topic, the answer to my hunch presented itself:

The other factor which leads to higher blood pressure in the winter is the body’s reaction to the colder temperatures – the Physiological Effect:

The colder winter temperatures cause the blood vessels to constrict which thus means a greater force is needed to circulate the blood through them.  This directly causes higher blood pressure, because:

” more pressure is needed to force blood through your narrowed veins and arteries.” 

What to make of all this?

Well, for starters – if you have normal BP in the summer, but then you notice that it climbs into the prehypertensive range during the winter months, there is really no need to panic.

Chances are as long as you keep doing the things which help maintain healthy blood pressure, such as healthy diet, regular exercise and managing stress, your BP will correct itself once the warmer temperatures return.

However, you may also want to consider trying a BP supplement during the winter months to help manage the change in BP.

OF NOTE:  BP fluctuations tend to be more pronounced as we age, and typically people over 65 will become more susceptible to the influence of temperature changes.

So, it is important for anyone who is on medications, to monitor their BP carefully as the seasons change and to stay in touch with their Doctor.

In some cases an alteration to dosage may be required, or perhaps even a different medication.

I would love to hear from you if you have found that the weather, and in particularly the change in seasons, have affected your blood pressure levels.  Please feel free to add comments below.

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