Seasonal variation in nocturnal home blood pressure fall: the Nagahama study

Abstract

Abnormalities in circadian blood pressure (BP) variation have been suggested to be associated with cardiovascular diseases and mortality. Factors affecting this variability need to be clarified to precisely evaluate the risk of circadian BP abnormalities. Given the seasonal differences in casual BP, it was hypothesized that nocturnal BP may also differ by season. Here, we aimed to clarify the seasonality of circadian BP variation, as well as the factors associated with this seasonality, in a large-scale general population (n = 4780). This is a cross-sectional study based on multiday BP values measured in the evening, during sleep, and in the morning. Measurements were taken at home using an automatic cuff-oscillometric device. The sleeping period was objectively defined by actigraphy. The nocturnal systolic BP fall was significantly less in individuals whose BP was measured during the summer season (summer, -5.8 ± 7.8%; middle (spring or autumn), -8.2 ± 7.5%; winter, -11.0 ± 7.7%; p < 0.001), resulting in higher frequencies of riser (summer, 19.9; middle, 12.8; winter, 7.8%) and non-dipper (summer, 51.4; middle, 46.3; winter, 37.0%) patterns in the summer season (p < 0.001). The results of linear regression analysis identified the middle (β = 0.154, p < 0.001) and summer season (β = 0.261, p < 0.001) as strong positive determinants for decreasing the nocturnal SBP fall. No seasonality was observed in day-to-day variability of the dipping pattern (Kendall's coefficient: winter, 0.527; middle, 0.539; summer, 0.515). The nocturnal BP fall was largely different by season, with a higher frequency of riser and non-dipper patterns in the summer. The seasonality might not be due to the seasonal difference in day-to-day variability of nocturnal BP changes.

The influence of the ambient temperature on blood pressure and how it will affect the epidemiology of hypertension in Asia

“…Interestingly, nocturnal SBP was positively related to the ambient temperature . Higher nocturnal BP and non‐dipping patterns of BP during the summer months have been confirmed in other studies . In an analysis of ABPM recordings of untreated individuals, the night‐to‐day ratio of BP (n = 897) was 2.4% higher in the summer and 1.8% lower in the winter.…”

“…BP was measured at home, and the sleeping period defined by actigraphy. The results showed that the fall in nocturnal SBP was significantly lower in the summer than in the winter, and there were significantly higher frequencies of riser and non‐dipper patterns of BP during the summer months as well . Although clinicians tend to reduce the dosage and number of antihypertensive medications during the summer months due to the decrease in the in‐office BP and fear of hypotensive episodes, the higher nocturnal BP and prevalence of risers and non‐dippers during the summer months may have clinical significance, suggesting the need for more active use of out‐of‐office BP monitoring during the summer months to optimize the control of BP variability, especially in high‐risk hypertensive patients…”

Improved home BP profile with dapagliflozin is associated with amelioration of albuminuria in Japanese patients with diabetic nephropathy: the Yokohama add-on inhibitory efficacy of dapagliflozin on albuminuria in Japanese patients with type 2 diabetes study (Y-AIDA study)

“…Extreme-dippers were defined as having nocturnal declines that were > 20% of the daytime systolic BP. Risers were defined as having nocturnal declines that were < 0% of the daytime systolic BP [27]. Daytime systolic BP in home BP measurement was defined as the average of the mean morning and evening home systolic BP.…”

Blood Pressure Non-Dipping and Obstructive Sleep Apnea Syndrome: A Meta-Analysis

“…The extent of day/night BP variations in population-based samples and, in general, hypertensive cohorts has been related to several factors such as age, ethnicity, intensity of diurnal physical activity, job stress, smoking habits, quality of sleep, seasonal influence, and co-morbidities [4,5,6].…”