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.

From: Association of sleep duration in middle and old age 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
  1. CI confidence intervals, HR hazard ratio, SD standard deviation.
  2. aFollow-up: mean = 7.4 years, SD = 4.7 years, range = 0.1–21.8 years.
  3. bHR estimated from a Cox regression adjusted for age (timescale), sex, ethnicity, education, and marital status.
  4. cAdditionally adjusted for alcohol consumption, physical activity, smoking status, and fruit and vegetable consumption.
  5. dAdditionally adjusted for BMI, hypertension, diabetes, cardiovascular disease, GHQ depression, and CNS medications.
  6. eTwo-sided P value for HR in comparison with the reference (ref.) category, without adjustment for multiple comparisons.