Table 1.
Characteristics of the sample in the analyses of global grey and white matter volumes in relation to NSF guideline adherence with the main statistical model (please see supplementary section S1.6 for characteristics of the samples in all other analyses)
| Sample characteristic | Participants sleeping as NSF recommended (7–9 hours per day) | Participants sleeping less than NSF recommended (<7 hours per day) | Participants sleeping more than NSF recommended (>9 hours per day) |
|---|---|---|---|
| Sample size (male/ female) | 24057 (11557/12500) |
7682 (3338/4344) |
380 (182/198) |
| Age mean (SD) | 63.65 (7.49) | 62.81 (7.62)* | 64.85 (7.53)* |
| Ethnic minority count (proportion) | 1931 (8.03%) | 742 (9.66%)* | 32 (8.42%) |
| Townsend index mean (SD) | −2.01 (2.65) | −1.77 (2.77)* | −1.53 (2.95)* |
| BMI mean (SD) | 26.35 (4.26) | 26.88 (4.66)* | 28.37 (5.49)* |
| Vascular/heart problems-medicated count (proportion) | 7892 (32.81%) | 2519 (32.79%) | 178 (46.84%)* |
| Diabetic count (proportion) | 1172 (4.87%) | 433 (5.64%)* | 46 (12.11%)* |
| Smoking count (proportion) | 8804 (36.60%) | 2873 (37.40%) | 153 (40.26%) |
| Alcohol consumer count (proportion) | 17479 (72.66%) | 5299 (68.98%)* | 248 (65.26%)* |
| Lifetime depression count (proportion) | 5508 (22.90%) | 1980 (25.77%)* | 150 (39.47%)* |
Significant differences in groups when compared with participants sleeping the NSF recommended time (less than 7 hours per day / more than 9 hours compared to 7–9 hours) are marked with asterisks. Characteristics were compared between groups with two-sample t-tests (for continuous variables) or with chi-squared tests (for participant proportions). Age is measured in years.