Table 1.
Characteristics of participants at baseline
| Characteristics | Total | Sleep regularity index | ||
|---|---|---|---|---|
| Irregular (Q1) | Moderate Irregular (Q2–Q4) | Regular (Q5) | ||
| Number of population | 79,666 | 15,934 | 47,799 | 15,933 |
| Age, mean (SD), year | 61.53 (7.87) | 62.26 (7.78) | 61.47 (7.85) | 60.98 (7.94) |
| BMI, mean (SD), kg/m2 | 26.62 (4.43) | 28.02 (4.95) | 26.52 (4.28) | 25.51 (3.96) |
| Sleep duration, mean (SD), hours | 7.22 (1.00) | 6.94 (1.24) | 7.26 (0.95) | 7.36 (0.81) |
| Townsend deprivation index, mean (SD) | −1.77 (2.79) | −1.28 (3.05) | −1.83 (2.75) | −2.06 (2.60) |
| Sex | ||||
| Female | 43,620 (54.75) | 6,188 (38.84) | 26,292 (55.01) | 11,140 (69.92) |
| Male | 36,046 (45.25) | 9,746 (61.16) | 21,507 (44.99) | 4,793 (30.08) |
| Ethnic background | ||||
| White | 77,124 (96.81) | 15,126 (94.93) | 46,370 (97.00) | 15,628 (98.09) |
| Non-White (mixed, Asian, Black, Chinese, and other ethnic groups) | 2,542 (3.19) | 808 (5.07) | 1,429 (3.00) | 305 (1.91) |
| Annual household income, £ | ||||
| <31,000 | 26,921 (33.79) | 6,388 (40.09) | 15,604 (32.65) | 4,929 (30.94) |
| ≥31,000 | 44,499 (55.86) | 7,960 (49.96) | 27,315 (57.15) | 9,224 (57.89) |
| Unknown/missing | 8,246 (10.35) | 1,586 (9.95) | 4,880 (10.20) | 1,780 (11.17) |
| Education status | ||||
| High | 34,475 (43.27) | 6,436 (40.39) | 20,927 (43.78) | 7,112 (44.64) |
| Middle | 37,803 (47.45) | 7,604 (47.72) | 22,580 (47.24) | 7,619 (47.82) |
| No above | 6,592 (8.28) | 1,694 (10.63) | 3,834 (8.02) | 1,064 (6.68) |
| Unknown/missing | 796 (1.00) | 200 (1.26) | 458 (0.96) | 138 (0.86) |
| Smoking status | ||||
| Never | 45,905 (57.62) | 8,244 (51.74) | 27,774 (58.11) | 9,887 (62.05) |
| Current | 5,147 (6.46) | 1,581 (9.92) | 2,879 (6.02) | 687 (4.31) |
| Previous | 28,401 (35.65) | 6,058 (38.02) | 17,016 (35.60) | 5,327 (33.43) |
| Unknown/missing | 213 (0.27) | 51 (0.32) | 130 (0.27) | 32 (0.21) |
| Alcohol consumption status | ||||
| Never | 2,265 (2.84) | 538 (3.38) | 1,279 (2.68) | 448 (2.81) |
| Current | 75,393 (94.64) | 14,841 (93.14) | 45,409 (95.00) | 15,143 (95.03) |
| Previous | 1,935 (2.43) | 537 (3.37) | 1,065 (2.22) | 333 (2.10) |
| Unknown/missing | 73 (0.09) | 18 (0.11) | 46 (0.10) | 9 (0.06) |
| Physical activity levela | ||||
| Low | 11,011 (13.82) | 2,607 (16.36) | 6,389 (13,37) | 2,015 (12.65) |
| Moderate | 49,306 (61.89) | 9,625 (60.41) | 29,830 (62.41) | 9,851 (61.83) |
| High | 19,349 (24.29) | 3,702 (23.23) | 11,580 (24.22) | 4,067 (25.52) |
| Diet qualityb | ||||
| Healthy | 53,281 (66.88) | 9,683 (60.77) | 32,145 (67.25) | 11,453 (71.88) |
| Unhealthy | 26,385 (33.12) | 6,251 (39.23) | 15,654 (32.75) | 4,480 (28.12) |
| Employment shift | ||||
| No | 42,915 (53.87) | 7,628 (47.87) | 26,289 (55.00) | 8,998 (56.47) |
| Yes | 6,289 (7.89) | 1,733 (10.88) | 3,597 (7.53) | 959 (6.02) |
| Unknown/missing | 30,462 (38.24) | 6,573 (41.25) | 17,913 (37.47) | 5,976 (37.51) |
| Season of accelerometer wear | ||||
| Spring | 18,059 (22.67) | 3,509 (22.02) | 10,897 (22.80) | 3,653 (22.93) |
| Summer | 20,688 (25.97) | 3,694 (23.18) | 12,469 (26.09) | 4,525 (28.40) |
| Autumn | 23,814 (29.89) | 4,816 (30.23) | 14,288 (29.89) | 4,710 (29.56) |
| Winter | 17,105 (21.47) | 3,915 (24.57) | 10,145 (21.22) | 3,045 (19.11) |
Note: Data are presented as mean (standard deviation) for continuous variables and n (%) for categorical variables.
Abbreviations: BMI, ‘body mass index’; MET, ‘metabolic equivalent tasks’; Q, ‘quantile’; SD, ‘standard deviation’.
a
Physical activity was divided into three levels according to metabolic equivalent tasks (MET): low (<600 MET minutes/week), medium (600–3,000 MET minutes/week), and high (>3,000 MET minutes/week).
b
Diet score was calculated based on the consumption of fruits, vegetables, processed meat, red meat, fish, whole grains, and refined grains. The diet score ranged from 0 to 7, with higher scores reflecting better diet quality, and ≥4 was considered a healthy diet.