Table 1.

Age-adjusted characteristics of the study population at 2001 baseline by rotating night shift duration

Variables
Duration of rotating night shift work (years)	0	<2	2-5.9	6-9.9	≥10
Proportion of Sample (%)	29	27	24	11	9
Age, yearsa	47.05 ± 4.60	46.64 ± 4.73	46.22 ± 4.70	46.27 ± 4.58	47.22 ± 4.28
Body Mass Index, kg/m2	25.66 ± 4.89	25.85 ± 4.98	26.22 ± 5.09	26.76 ± 5.30	27.21 ± 5.33
Physical activity, MET-hours/weekb	19.22 ± 21.66	19.47 ± 21.55	20.33 ± 22.66	20.35 ± 22.73	20.15 ± 22.96
Alcohol intake, g/day	3.87 ± 7.04	4.07 ± 7.28	4.14 ± 7.30	3.98 ± 7.34	3.52 ± 6.64
Alternate Health Eating Indexc	47.82 ± 10.69	47.74 ± 10.78	47.91 ± 10.63	47.68 ± 10.81	47.14 ± 10.72
Sleep, ≤ 6 hours over a 24-hour period, %	25	27	31	33	40
First degree relative history of melanoma, %	11	11	12	12	12
Red or blonde hair, %	20	20	20	20	17
Moles, ≥ 10 on lower legs, %	15	15	14	14	13
Artificial tanning, ≥ 6 times/year at ages 25-35, %	3	3	3	3	3
Time spent in sun, ≥ 5 hours/week at ages 25-35, %	43	43	44	44	45
Severe sunburns, ≥ 6 at ages 15-20, %	9	10	11	10	11
Skin sensitivity to burningd, %	42	41	41	41	41
Annual UV-B flux at residence, ≥ 145 R-B unitse, %	26	23	21	19	16
Sleep not usually adequate, %	46	48	51	52	57
Sleepy ≥4 days/week, %	11	12	12	13	14
Snore most nights, %	14	15	17	18	19
Restless legs syndrome	2	2	2	2	2
Current smoker, %	7	8	10	10	12
Married, %	82	82	79	76	75
In top 20 percent of economic ladderf, %	12	12	11	10	9
Oral contraceptive use, ≥ 8 years, %	22	22	22	22	22
Current use of postmenopausal hormonesg, %	66	64	64	62	59

Values are means ± SD or percentages and are standardized to the age distribution of the study population

^aValue is not age-adjusted

^bMetabolic equivalents from recreational and leisure-time activities

^cScore of 0-100 measuring adherence to a dietary pattern most predictive of disease risk

^dSkin reaction after two or more hours in the sun without sunscreen on a bright sunny day during childhood and adolescence (none/some redness, burn, painful/blistering burn)

^eMeasured in Robertson-Berger units (count×10⁻⁴)

^fSelf-reported economic status compared to others

^gCalculated among postmenopausal women only