Table 2 Association between sleep duration at 50, 60, and 70 years and incidence of dementia.

From: Association of sleep duration in middle and old age with incidence of dementia

 

N cases/N total

Incidence rate per 1000 persons-years

Model 1: adjusted for sociodemographic variablesa

Model 1 + behavioural factorsb

Model 1 + health-related factorsc

Fully adjusted model

HR (95%CI)

P valued

HR (95%CI)

P valued

HR (95%CI)

P valued

HR (95%CI)

P valued

Sleep duration at age 50e

521/7959

         

 Short: ≤6 h

211/3149

2.8 (2.4–3.2)

1.28 (1.06–1.55)

0.01

1.27 (1.05–1.54)

0.01

1.22 (1.01–1.48)

0.04

1.22 (1.01–1.48)

0.04

 Normal: 7 h

219/3624

2.4 (2.1–2.7)

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

 Long: ≥8 h

91/1186

3.0 (2.4–3.7)

1.25 (0.98–1.59)

0.08

1.25 (0.98–1.60)

0.07

1.24 (0.97–1.59)

0.09

1.25 (0.98–1.60)

0.07

Sleep duration at age 60e

409/7164

         

 Short: ≤6 h

192/2759

4.7 (4.0–5.4)

1.48 (1.19–1.84)

<0.001

1.46 (1.17–1.82)

0.001

1.38 (1.11–1.73)

0.004

1.37 (1.10–1.72)

0.005

 Normal: 7 h

142/2988

3.2 (2.7–3.7)

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

 Long: ≥8 h

75/1417

3.6 (2.8–4.4)

1.15 (0.87–1.52)

0.33

1.17 (0.88–1.55)

0.28

1.13 (0.85–1.50)

0.39

1.15 (0.87–1.52)

0.34

Sleep duration at age 70e

392/6516

         

 Short: ≤6 h

171/2429

9.3 (7.9–10.7)

1.33 (1.06–1.68)

0.004

1.29 (1.03–1.63)

0.005

1.26 (1.00–1.60)

0.04

1.24 (0.98–1.57)

0.10

 Normal: 7 h

131/2578

6.8 (5.6–7.9)

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

1 (ref.)

 

 Long: ≥8 h

90/1509

8.1 (6.4–9.7)

1.22 (0.94–1.60)

0.39

1.13 (0.91–1.55)

0.34

1.18 (0.90–1.55)

0.22

1.15 (0.88–1.51)

0.60

  1. CI confidence intervals, HR hazard ratio, SD standard deviation.
  2. aHR estimated from a Cox regression adjusted for age (timescale), sex, ethnicity, education, and marital status.
  3. bAdditionally adjusted for alcohol consumption, physical activity, smoking status, and fruit and vegetable consumption.
  4. cAdditionally adjusted for BMI, hypertension, diabetes, cardiovascular disease, GHQ depression, and CNS medications.
  5. dTwo-sided P value for HR in comparison with the reference (ref.) category, without adjustment for multiple comparisons.
  6. eFollow-up: at age 50, mean = 24.6 years, SD = 7.0 years, range = 0.18–33.6 years; at age 60, mean = 14.8 years, SD = 5.9 years, range = 0.11–33.6 years; at age 70, mean = 7.5 years, SD = 4.7 years, range = 0.04–21.8 years.
Back to article page