CHICAGO – Keeping the bedroom warm at night during the cold winter months curbs the morning surge in blood pressure, according to a randomized Japanese trial.
This finding may help explain the well-established increased mortality due to heart disease and stroke during the winter months.
The data from this study indicate that if the ambient bedroom temperature is lower, morning blood pressure will be higher, the morning blood pressure surge will be greater, and there will be increased blood pressure variability during the 24-hour day, increasing the risk of a cardiac or cerebrovascular event, Dr. Keigo Saeki asserted at the meeting.
The investigators randomized 140 healthy 18- to 65-year-old participants to spend a night in either an inadequately heated room at 12° C (54° F) or a room maintained at 22° C (72° F). Participants were required to remain in the room between 9 p.m. and 6 a.m., stay awake until 11 p.m., and rise by 6 a.m. Blood pressure was measured every 30 minutes through the night. The subjects had access to all the clothing and blankets they needed to stay comfortable, said Dr. Saeki of Nara (Japan) Medical University.
Mean systolic blood pressure during the first 2 hours after awakening in the morning was 121.1 mm Hg in subjects who slept in the cold room, significantly higher than the 114.0 mm Hg for those in the warm room. The morning systolic blood pressure surge also was significantly higher in subjects after a night in the inadequately heated room: 21.9 mm Hg, compared with 14.3 mm Hg after a night in the warm room. However, there was no difference between the two study groups in terms of lowest sleeping systolic blood pressure, which averaged 99 mm Hg across three readings.
Dr. Saeki declared having no relevant disclosures.