TABLE 2.

Isolated nocturnal hypertension in relation to host and environmental factors

	Isolated nocturnal hypertension
Explanatory variable	Odds ratio (95%CI)	P
Host factors
Nighttime heart rate (+10 beats/min)	1.82 (1.25 to 2.65)	.0018
Sleep duration, (+1 h)	0.81 (0.65 to 1.02)	.0747
Environmental factors
Relative humidity (+10%)	0.82 (0.67 to 1.00)	.0499

In the stepwise logistic regression analyses, the p‐values for explanatory variables to enter and stay in the model were set at 0.10. The host factors considered for entry in the model were age, sex, body mass index, current smoking and drinking, diabetes mellitus, sleep after 23:00, 24‐h, daytime and nighttime heart rate, sleep duration, serum total cholesterol, high‐density lipoprotein cholesterol, triglycerides, and creatinine. The environmental cues encompassed season, mean daily outdoor temperature, atmospheric pressure, relative humidity and wind speed. We first searched host factors in relation to isolated nocturnal hypertension, and then in the analyses on environmental factors, the identified two host factors were forced to be included in the model, from which the odds ratios and P values shown in the table were derived.