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. Author manuscript; available in PMC: 2013 Aug 1.
Published in final edited form as: J Invest Dermatol. 2012 Aug 30;133(2):565–567. doi: 10.1038/jid.2012.285

Table 1.

Age-standardized baseline characteristics of the study participants by status of working rotating night shifts: Nurses’ Health Study (1988) and Nurses’ Health Study II (1989)1.

Characteristics Nurses’ Health Study working rotating night shifts Nurses’ Health Study II working rotating night shifts
Never
n=25,765		 Ever
n=36,722		 P3 Never
n=36,660		 Ever
n=58,901		 P3
Age 2, mean (SD), year 52.8 (6.9) 53.5 (6.9) <0.0001 34.4 (4.7) 34.5 (4.6) 0.45
Body mass index, kg/m2, mean (SD) 25.1 (4.6) 25.6 (4.8) <0.0001 23.8 (4.8) 24.1 (5.0) <0.0001
Current smokers (yes, %) 14.5 16.2 <0.0001 12.6 14.2 <0.0001
Alcohol intake, g/d, mean (SD) 6.0 (10.1) 6.0 (10.3) 0.43 3.0 (6.1) 3.2 (6.1) <0.0001
Physical activity, metabolic equivalent hours/wk, mean (SD) 14.9 (21.0) 16.3 (22.5) <0.0001 19.4 (25.1) 21.6 (27.7) <0.0001
1

Values are means (SD) or percentages and are standardized to the age distribution of the study population.

2

Value is not age adjusted.

3

P values are calculated by t-test or χ2 test.