The association of night work and the duration of the working week with the prevalence of vitamin D insufficiency and log 25(OH)D concentrations in British men and women aged 45 years*
| 25(OH)D geometric mean, nmol/l | 25(OH)D <50 nmol/l, % | Model 1† coefficient (95% CI) | Model 2† coefficient (95% CI) | Model 3† coefficient (95% CI) | Model 4† coefficient (95% CI) | |
| Men | ||||||
| Night work | ||||||
| No | 54.3 | 38.8 | Ref | Ref | Ref | Ref |
| Yes | 57.5 | 34.6 | 0.04 (−0.01 to 0.10) | 0.03 (−0.02 to 0.09) | 0.03 (−0.03 to 0.09) | 0.04 (−0.01 to 0.10) |
| p Value | 0.078 | 0.23 | 0.15 | 0.24 | 0.31 | 0.12 |
| Hours worked | ||||||
| <35 | 51.0 | 36.0 | −0.03 (−0.10 to 0.04) | −0.03 (−0.10 to 0.04) | −0.03 (−0.10 to 0.04) | −0.03 (−0.10 to 0.04) |
| 35–40 | 52.9 | 40.9 | Ref | Ref | Ref | Ref |
| 41–48 | 54.7 | 38.7 | 0.04 (0.00 to 0.08) | 0.04 (0.00 to 0.08) | 0.04 (0.00 to 0.07) | 0.03 (−0.01 to 0.07) |
| >48 | 55.0 | 37.9 | 0.04 (0.01 to 0.07) | 0.04 (0.01 to 0.07) | 0.05 (0.01 to 0.08) | 0.04 (0.00 to 0.07) |
| p Value for trend | 0.012 | 0.30 | 0.005 | 0.004 | 0.001 | 0.011 |
| Women | ||||||
| Night work | ||||||
| No | 52.5 | 41.0 | Ref | Ref | Ref | Ref |
| Yes | 47.8 | 47.4 | −0.09 (−0.16 to −0.02) | −0.09 (−0.16 to -0.02) | −0.08 (−0.15 to −0.02) | −0.10 (−0.16 to −0.03) |
| p Value | 0.012 | 0.10 | 0.007 | 0.009 | 0.014 | 0.005 |
| Hours worked | ||||||
| <35 | 53.4 | 38.7 | 0.05 (0.02 to 0.09) | 0.05 (0.02 to 0.09) | 0.05 (0.01 to 0.08) | 0.03 (−0.01 to 0.07) |
| 35–40 | 50.4 | 44.7 | Ref | Ref | Ref | Ref |
| 41–48 | 50.0 | 45.8 | −0.02 (−0.08 to 0.03) | −0.03 (−0.09 to 0.03) | −0.02 (−0.08 to 0.04) | −0.03 (−0.09 to 0.02) |
| >48 | 50.7 | 45.2 | −0.02 (−0.08 to 0.04) | −0.03 (−0.09 to 0.03) | −0.03 (−0.09 to 0.03) | −0.05 (−0.11 to 0.01) |
| p Value for trend | 0.007 | 0.004 | ≤0.001 | ≤0.001 | ≤0.001 | 0.001 |
Data shown for participants who were at paid work.
↵* Analyses on hours worked based on information from 3157 men and 2979 women, and analyses on night work on 2284 men and 2212 women with available information. Missing data on covariates have been imputed.
↵† Model 1 adjusted for season. Model 2 adjusted for season and social class (birth and age 42 years). Model 3 adjusted for season, social class (birth and age 42 years) and BMI. Model 4 adjusted for season, social class (birth and age 42 years), BMI, smoking, alcohol, physical activity, PC/TV leisure time, time spent outdoors, oily fish and vitamin D supplement.
BMI, body mass index; 25(OH)D, 25-hydroxyvitamin D.