Living in a cold home makes you more likely to suffer from high blood pressure, research suggests.
A study of almost 4,700 people in their own homes found for every decrease in temperature, there was a small jump in blood pressure.
Scientists now believe turning up the thermostat could help millions of patients manage their hypertension – the medical term for high blood pressure.
University College London researchers were unable to identify a threshold for a warm enough home.
But they suggest that keeping living rooms to a minimum of 21°C (70 °F) could be advisable for general health.
A study found that for every decrease in temperature, there was a small jump in blood pressure
Nurses took blood pressure readings from 4,659 participants in their own homes, along with recording the temperature.
They uncovered a statistically significant link between indoor temperatures and a person’s blood pressure.
For every decrease in temperature, there was a small jump in blood pressure, Dr Stephen Jivraj and colleagues found.
Blood pressure readings consist of two figures given together – systolic is the top number and diastolic the bottom.
Systolic is the pressure when the heart pushes blood out. Diastolic is the pressure when the heart rests between beats.
Ideal blood pressure is considered to be between 90/60mmHg and 120/80mmHg, according to NHS Choices.
High blood pressure affects one in three adults, more than 17 million of the British population and around 75 million in the US.
The new study found every 1°C (34°F) decrease in indoor temperature was linked to rises of 0.48mmHg in systolic and 0.45mmHg in diastolic blood pressure.
Average systolic and diastolic blood pressure were 126.64mmHg and 74.52mmHg, respectively, for people in the coolest homes in the study.
This was compared with 121.12mmHg and 70.51mmHg, respectively, in the warmest homes.
Dr Jivraj and colleagues published their findings in the Journal of Hypertension.
He said: ‘Our research has helped to explain the higher rates of hypertension, as well as potential increases in deaths from stroke and heart disease, in the winter.
‘Among other diet and lifestyle changes people can make to reduce blood pressure, our findings suggest keeping homes a bit warmer could also be beneficial.’
During bouts of particularly cold weather, officials issue warnings to people whose health is particularly at risk, including older people.
Official advice urges people to heat their homes to at least 18°C (64.4°F).