Table 4.

Relative Risk of SBP Nondipping at 7.4-Year Follow-up According to Sleep Quality.

Characteristics	Total sample, n	Incident nondipping, n(%)	RR (95% CI)
			Unadjusted	Adjusted
Insomnia
Yes	55	14 (25.5)	1.5 (0.8, 3.1)	1.4 (0.5, 3.0)
No	115	19 (16.5)	1.0 (Ref)	1.0 (Ref)
Missing	79
Difficulty falling asleep
Often/almost always	15	4 (26.7)	1.4 (0.5, 4.1)	1.3 (0.4, 3.9)
Sometimes/less	184	26(18.5)	1.0 (Ref)	1.0 (Ref)
Missing	50
Sleep latency, hours	249	49 (19.7)	1.1 (0.4, 3.7)	1.1 (0.3, 3.5)
Waking after sleep onset, per hour	249	48 (19.7)	1.7 (1.1, 2.6)*	2.1 (1.3, 3.5)*
Total sleep time
Tst< 6 h	85	18 (21.2)	1.9 (0.9, 4.0)	1.8 (0.9, 4.1)
6 h ≤TST <7h	96	11 (11.5)	1.0 (Ref)	1.0 (Ref)
7 h ≤TST <8h	53	14 (26.4)	2.3 (1.0, 5.1) §	2.1 (1.1, 5.1)*
TST≥ 8 h	15	6 (40.0)	3.5 (1.3, 9.4)*	3.7 (1.3, 10.7)*
Sleep efficiency
Sleep efficiency ≥ 0.8	191	32 (16.8)	1.0 (Ref)	1.0 (Ref)
Sleep efficiency < 0.8	58	17 (29.3)	1.8 (1.0, 3.3)*	1.9 (1.1, 3.4)*

Abbreviations: CI, confidence interval; RR, relative risk; tst, total sleep time, SBP: systolic blood pressure.

Analysis adjusted for baseline age, sex, BMI at baseline and follow-up, current smoking, hypertension, alcohol consumption from the baseline visit; duration of follow-up; self-reported hours of weekly physical exercise, use of sedative medication, and whether or not an individual was on antihypertensive medication at any time during the follow-up time period, nap frequency, leg movements, and sleep disordered breathing (AHI).

^*P <0.05.

^§P=0.05.