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Updated: Jul 4, 2026
Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry
Published on: May 17, 2016
Opposite seasonal variation in nighttime and morning blood pressure: a longitudinal study of patients with
Tatsuya Maruhashi1, Yoshihiko Kinoshita2, Ryoji Ozono3
1Division of Radiation Medical Science, Department of Regenerative Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
Background:
Longitudinal data on seasonal variations in nighttime blood pressure (BP) obtained through home blood pressure monitoring (HBPM) are scarce. We examined whether nighttime BP is elevated in summer compared to winter in patients undergoing hypertension treatment.
Methods:
Nighttime BP was measured for 7 days using an HBPM device in 419 participants at baseline, and 136 of those underwent follow-up nighttime BP measurements at 6 months without any modification of antihypertensive therapy. Morning BP was also measured in some participants.
Results:
The baseline cross-sectional analysis indicated that nighttime systolic BP was elevated in summer compared to winter (adjusted mean difference, 8.3 mmHg; 95% confidence interval [CI], 4.7-11.8). The longitudinal analyses revealed that nighttime systolic BP was higher in summer than in winter among winter-to-summer participants (mean difference, 5.1 mmHg; 95% CI, 3.1-7.0; n = 36) and among summer-to-winter participants (mean difference, 2.6 mmHg; 95% CI, 0.3-5.0; n = 23). Conversely, morning systolic BP was lower in summer than in winter among winter-to-summer participants (mean difference, 3.8 mmHg; 95% CI, 0.7-7.0) and among summer-to-winter participants (mean difference, 3.7 mmHg; 95% CI, 1.0-6.4). In sensitivity analyses, seasonal variations in room temperature were positively correlated with changes in nighttime systolic BP (r = 0.43; 95% CI, 0.21-0.60) and negatively correlated with changes in morning systolic BP (r = -0.46; 95% CI, -0.63 to -0.25).
Conclusions:
Nighttime systolic BP increased from winter to summer in association with higher room temperature and exhibited an inverse seasonal pattern compared to morning BP.
Clinical Trial Registration:
University Hospital Medical Information Network Clinical Trials Registry UMIN000019173.
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