Table 4.

Association of of trajectories of sleep duration (using data on sleep duration at 50, 60, and 70 years, N cases/N total = 426/6875) with incidence of dementia.

Trajectories of sleep duration between age 50 and 70a	N cases/N total	Incidence rate per 1000 persons-years	Model 1: adjusted for sociodemographic variablesb		Model 1 + behavioural factorsc		Model 1 + health-related factorsd		Fully adjusted model
			HR (95%CI)	P valuee	HR (95%CI)	P valuee	HR (95%CI)	P valuee	HR (95%CI)	P valuee
Persistent short	103/1358	10.5 (8.5–12.5)	1.40 (1.08–1.81)	0.01	1.35 (1.05–1.75)	0.02	1.32 (1.02–1.72)	0.03	1.30 (1.00–1.69)	0.048
Persistent normal	141/2520	7.3 (6.1–8.5)	1 (ref.)		1 (ref.)		1 (ref.)		1 (ref.)
Persistent long	35/461	9.9 (6.6–13.1)	1.32 (0.91–1.91)	0.15	1.27 (0.88–1.85)	0.20	1.32 (0.91–1.91)	0.15	1.28 (0.88–1.85)	0.20
Change from short to normal	61/1086	8.2 (6.1–10.2)	1.23 (0.91–1.66)	0.18	1.21 (0.90–1.64)	0.21	1.21 (0.90–1.64)	0.21	1.20 (0.89–1.63)	0.23
Change from normal to long	47/946	7.1 (5.0–9.1)	1.04 (0.75–1.45)	0.81	1.03 (0.74–1.44)	0.85	1.03 (0.74–1.44)	0.86	1.02 (0.73–1.42)	0.90
Change from normal to short	39/504	9.6 (6.6–12.6)	1.21 (0.84–1.73)	0.30	1.17 (0.82–1.68)	0.38	1.15 (0.80–1.65)	0.44	1.13 (0.79–1.62)	0.50

CI confidence intervals, HR hazard ratio, SD standard deviation.

^aFollow-up: mean = 7.4 years, SD = 4.7 years, range = 0.1–21.8 years.

^bHR estimated from a Cox regression adjusted for age (timescale), sex, ethnicity, education, and marital status.

^cAdditionally adjusted for alcohol consumption, physical activity, smoking status, and fruit and vegetable consumption.

^dAdditionally adjusted for BMI, hypertension, diabetes, cardiovascular disease, GHQ depression, and CNS medications.

^eTwo-sided P value for HR in comparison with the reference (ref.) category, without adjustment for multiple comparisons.