Background
Material and methods
Participants
Study design
Study questionnaires
Cardiovascular risk markers
Statistical analysis
Results
Variable in % (n) or arithmetic mean (standard deviation, SD) | Total | Rotating night shift workers | Day workers | pa |
---|---|---|---|---|
100% (N = 70) | 45.7% (32) | 54.3% (38) | ||
Sociodemographic characteristics | ||||
Job title | < 0.001 | |||
Nurse | 71.2% (47) | 93.3% (28) | 52.8% (19) | |
Head nurse | 6.1% (4) | 3.3% (1) | 8.3% (3) | |
Nurse assistant | 1.5% (1) | 3.3% (1) | 0.0% (0) | |
Administrative personnel | 21.2% (14) | 0.0% (0) | 38.9% (14) | |
Age (years mean, SD) | 52.0 (4.0) | 52.0 (4.0) | 52.0 (4.0) | 0.691 |
Gender | ||||
Female | 91.4% (64) | 87.5% (28) | 94.7% (36) | 0.402 |
Male | 8.6% (6) | 12.5% (4) | 5.3% (2) | |
Education | 0.369 | |||
Compulsory schooling (elementary) | 1.6% (1) | 0.0% (0) | 2.6% (1) | |
Secondary | 46.9% (30) | 38.5% (10) | 52.6% (20) | |
Secondary with university entrance qualification | 29.7% (19) | 30.8% (8) | 28.9% (11) | |
Tertiary (university degree or higher) | 21.9% (14) | 30.8% (8) | 15.8% (6) | |
Marital status | 1.000 | |||
Single | 12.5% (8) | 11.5% (3) | 13.2% (5) | |
Married or in civil union | 67.2% (43) | 69.2% (18) | 65.8% (25) | |
Divorced/widowed | 20.3% (13) | 19.2% (5) | 21.1% (8) | |
Domestic situation (nr. of persons in household) | 0.475 | |||
1 | 25.4% (16) | 26.9% (7) | 24.3% (9) | |
2 | 25.4% (16) | 15.4% (4) | 32.4% (12) | |
3 | 23.8% (15) | 26.9% (7) | 21.6% (8) | |
4–5 | 25.4% (16) | 30.8% (8) | 21.6% (8) | |
Ethnicity | 0.346 | |||
White | 59.6% (31) | 54.5% (12) | 63.3% (19) | |
Asian | 7.7% (4) | 13.6% (3) | 3.3% (1) | |
Black or Middle East | 1.9% (1) | 4.5% (1) | 0.0% (0) | |
Other | 30.8% (16) | 27.3% (6) | 33.3% (10) | |
Work hours per week (mean, SD) | 39.09 (10.54) | 41.45 (9.36) | 34.92 (11.57) | 0.074 |
Total years in alternating shifts (mean, SD) | 18.21 (11.92) | 26.76 (6.78) | 8.02 (8.02) | < 0.001 |
Years in current rotation plan (mean, SD) | 21 (10) | 24 (9) | 14 (10) | 0.005 |
Night shifts per month (mean, SD) | – | 5.8 (3.1) | – | – |
Lifestyle and sleep-related characteristics | ||||
Smoking status | 0.847 | |||
Smoker | 31.7% (20) | 30.8% (8) | 32.4% (12) | – |
No. of cigarettes per week (mean, SD) | 345 (233.18) | 300 (279.64) | 367.50 (219.41) | 0.901 |
Former smoker | 22.2% (14) | 19.2% (5) | 24.3% (9) | – |
Never smoked | 46.0% (29) | 50.0% (13) | 43.2% (16) | – |
Current alcohol consumption | 0.685 | |||
Yes | 38.6% (22) | 41.7% (10) | 36.4% (12) | – |
No. of alcoholic beverages per week (mean, SD) | 1.34 (2.30) | 1.48 (2.47) | 1.24 (2.19) | 0.698 |
No | 61.4% (35) | 58.3% (14) | 63.6% (21) | – |
Caffeine consumption | 0.253 | |||
Yes | 87.5% (56) | 80.8% (21) | 92.1% (35) | – |
No. of cups of coffee per day (mean, SD) | 2.72 (1.62) | 2.42 (1.96) | 2.93 (1.30) | 0.120 |
No. of cups of caffeinated drinks per day (mean, SD) | 3.02 (2.15) | 2.85 (2.74) | 3.15 (1.62) | 0.179 |
No | 12.5% (8) | 19.2% (5) | 7.9% (3) | – |
Current sleep problem | 0.159 | |||
Yes | 62.9% (39) | 73.1% (19) | 55.6% (20) | – |
Nights per week (mean, SD) | 3.15 (2.01) | 2.79 (1.87) | 3.50 (2.12) | 0.536 |
No | 37.1% (23) | 26.9% (7) | 44.4% (16) | – |
Wake up in the middle of the night | 0.447 | |||
Yes | 69.5% (41) | 75.0% (18) | 65.7% (23) | |
No | 30.5% (18) | 25.0% (6) | 34.3% (12) | |
Trouble falling asleep | 0.001 | |||
Yes | 55.4% (31) | 82.6% (19) | 36.4% (12) | |
No | 44.6% (25) | 17.4% (4) | 63.6% (21) | |
Daytime functioning impairment due to sleep problem | 0.351 | |||
None | 13.1% (8) | 11.5% (3) | 14.3% (5) | |
Minimal | 31.1% (19) | 23.1% (6) | 37.1% (13) | |
Moderate | 37.7% (23) | 46.2% (12) | 31.4% (11) | |
Serious | 16.4% (10) | 19.2% (5) | 14.3% (5) | |
Severe | 1.6% (1) | 0.0% (0) | 2.9% (1) | |
Physical activity (hours per week) | 4.39 (2.82) | 3.77 (1.86) | 4.79 (3.28) | 0.568 |
Chronotype | ||||
Total MEQ score (mean, SD)a | 58 (9) | 57 (9) | 60 (10) | 0.538 |
Self-assessment | 0.895 | |||
Clearly evening type | 6.7% (2) | 6.7% (1) | 6.7% (1) | |
Rather evening type | 33.3% (10) | 26.7% (4) | 40.0% (6) | |
Rather morning type | 23.3% (7) | 26.7% (4) | 20.0% (3) | |
Clearly morning type | 36.7% (11) | 40.0% (6) | 33.3% (5) |
Variable in % (n) or arithmetic mean (standard deviation, SD) | Total | Rotating night shift workers | Day workers | p* |
---|---|---|---|---|
Quality of life (WHO-QoL-BREF) | ||||
Domain 1 (physical health) | 16.59 (1.92) | 16.80 (1.85) | 16.45 (1.97) | 0.462 |
Domain 2 (psychological) | 16.26 (2.03) | 16.51 (2.01) | 16.08 (2.05) | 0.783 |
Domain 3 (social relationships) | 15.41 (2.49) | 15.46 (1.92) | 15.37 (2.84) | 0.972 |
Domain 4 (environment) | 16.11 (2.26) | 16.11 (1.82) | 16.11 (2.54) | 0.661 |
Satisfaction with own capacity for work | 0.652 | |||
Dissatisfied | 1.6% (1) | 0.0% (0) | 2.7% (1) | |
Neither satisfied nor dissatisfied | 7.9% (5) | 11.5% (3) | 5.4% (2) | |
Satisfied | 57.1% (36) | 50.0% (13) | 62.2% (23) | |
Very satisfied | 33.3% (21) | 38.5% (10) | 29.7% (11) | |
Assessment of own quality of life | 0.958 | |||
Very poor | 0.0% (0) | 0.0% (0) | 0.0% (0) | |
Poor | 4.7% (3) | 3.8% (1) | 5.3% (2) | |
Neither poor nor good | 18.8% (12) | 15.4% (4) | 21.1% (8) | |
Good | 56.3% (36) | 65.4% (17) | 50.0% (19) | |
Very good | 20.3% (13) | 15.4% (4) | 23.7% (9) | |
Satisfaction with own health | 0.569 | |||
Dissatisfied | 9.4% (6) | 7.7% (2) | 10.5% (4) | |
Neither satisfied nor dissatisfied | 17.2% (11) | 11.5% (3) | 21.1% (8) | |
Satisfied | 56.3% (36) | 65.4% (17) | 50.0% (19) | |
Very satisfied | 17.2% (11) | 15.4% (4) | 18.4% (7) | |
Work ability index (WAI) | ||||
WAI total score (mean, SD) | 47 (4) | 47 (5) | 47 (4) | 0.941 |
Work ability category | 0.134 | |||
Excellent | 77.8% (21) | 63.6% (7) | 87.5% (14) | |
Good | 18.5% (5) | 27.3% (3) | 12.5% (2) | |
Moderate | 3.7% (1) | 9.1% (1) | 0.0% (0) | |
Poor | 0.0% (0) | 0.0% (0) | 0.0% (0) |
Variable in % (n) or arithmetic mean (standard deviation, SD) | Total | Rotating shift workers | Day workers | p* |
---|---|---|---|---|
Anthropometric measures | ||||
Body mass index, BMI (mean, SD) | 25.66 (4.98) | 25.89 (6.77) | 25.53 (3.84) | 0.528 |
Total body fat (% of body weight) (mean, SD) | 30.22 (6.58) | 31.25 (6.53) | 29.68 (6.65) | 0.585 |
Basic metabolic rate, BMR (kJ/day) (mean, SD) | 1420 (204) | 1410 (244) | 1425 (183) | 0.389 |
Total muscle mass (kg) (mean, SD) | 45.44 (6.33) | 45.07 (7.34) | 45.62 (5.87) | 0.533 |
Total bone mass (kg) (mean, SD) | 2.43 (0.33) | 2.40 (0.39) | 2.44 (0.31) | 0.469 |
Visceral fat level (Range 1 to 59) | 6 (2) | 6 (3) | 6 (2) | 0.840 |
Extracellular water (% of body water) (mean, SD) | 43.62 (2.87) | 44.50 (1.57) | 43.15 (3.30) | 0.145 |
Total body water (% of body weight) (mean, SD) | 49.61 (4.84) | 48.75 (4.74) | 50.04 (4.90) | 0.577 |
Carotid intima media thickness (CIMT) | ||||
Average CIMT of left ACC/ACI/ACE | 0.598 (0.088) | 0.589 (0.077) | 0.603 (0.095) | 0.788 |
Maximum CIMT of left ACC/ACI/ACE | 0.72 (0.11) | 0.70 (0.09) | 0.73 (0.12) | 0.656 |
Average CIMT of right ACC/ACI/ACE | 0.57 (0.10) | 0.57 (0.09) | 0.57 (0.11) | 0.890 |
Maximum CIMT of right ACC/ACI/ACE | 0.69 (0.11) | 0.68 (0.09) | 0.70 (0.12) | 0.682 |
Blood CVD biomarkers | ||||
C‑reactive protein (CRP) (mg/dl) | 0.19 (0.24) | 0.25 (0.31) | 0.15 (0.17) | 0.061 |
Interleukin‑6 (IL‑6; pg/mL) | 2.26 (1.35) | 2.49 (1.68) | 2.13 (1.13) | 0.590 |
Ferritin (mg/dl) | 77.30 (62.06) | 79.07 (65.22) | 76.29 (61.13) | 0.965 |
NT pro Brain natriuretic peptide (NT proBNP) (pg/ml) | 62.13 (48.42) | 66.78 (54.27) | 59.47 (45.37) | 0.773 |
Triglycerides (mg/dl) | 117 (56) | 117 (50) | 118 (60) | 0.779 |
High-density lipoprotein (HDL; mg/dl) | 66 (18) | 65 (19) | 67 (17) | 0.739 |
Low-density lipoprotein (LDL; mg/dl) | 115.63 (28.21) | 106.48 (21.18) | 120.86 (30.59) | 0.128 |
Cholesterol (total; mg/dl) | 205 (31) | 195 (26) | 211 (33) | 0.104 |
Cholesterol (total)/HDL ratio | 3.29 (0.87) | 3.17 (0.71) | 3.36 (0.95) | 0.887 |
Selenium (µg/l) | 84.75 (11.26) | 89.10 (16.97) | 80.40 (4.10) | 1.000 |
Zinc (mg/l) | 0.92 (0.18) | 0.85 (0.18) | 0.96 (0.17) | 0.046 |
Copper (mg/l) | 1.15 (0.29) | 1.14 (0.22) | 1.15 (0.32) | 0.624 |
Crude difference (95% CI) | Age-adjusted difference (95% CI) | MV-adjusted difference (95% CI)a | |
---|---|---|---|
C‑reactive protein (CRP) (mg/dl) | 0.02 (−0.08, 0.12) | 0.03 (−0.10, 0.17) | 0.01 (−0.22, 0.23) |
Interleukin‑6 (IL‑6; pg/mL) | 1.00 (−0.11, 2.11) | 1.02 (0.03, 2.01) | 0.67 (−0.6, 1.94) |
Ferritin (ng/mL) | −15.5 (−67.8, 36.9) | −0.9 (−29.5, 27.7) | −2.95 (−52.2, 46.3) |
Brain natriuretic peptide (pg/mL) | −17.2 (−34.2, −0.19) | −18.5 (−1.8, −35.2) | −14.8 (−40.9, 11.3) |
Triglycerides (mg/dL) | −23.8 (−65.0, 17.5) | −15 (−67, 37) | −31.0 (−73.6, 11.7) |
High-density lipoprotein (HDL; mg/dl) | −8.0 (−26.1, 10.1) | −6.8 (−24, 10.5) | −2.61 (−21.2, 15.9) |
Low-density lipoprotein (LDL; mg/dl) | −2.7 (−25.9, 20.5) | −13.2 (−42.5, 16.2) | −15.9 (−54.9, 23.0) |
Cholesterol (total; mg/dl) | −24.5 (−43.8, −5.2) | −26.5 (−15.1, −37.9) | −18.9 (−54.1, 16.3) |
Cholesterol (total)/HDL ratio | 0.2 (−0.51, 0.91) | −18.5 (−37.1, 0.18) | −0.34 (−1.18, 0.50) |
Zinc (mg/l) | −0.06 (−0.17, 0.05) | −0.11 (−0.24, 0.02) | −0.15 (−0.37, 0.06) |
Copper (mg/l) | 0.01 (−0.22, 0.24) | −0.04 (−0.22, 0.15) | 0.05 (−0.30, 0.39) |