| Japan (N = 516) | US (N = 516) | p for difference |
---|---|---|---|
N (%) | N (%) | ||
Gender (male) | 260 (50.4) | 258 (50.0) | – |
Age range (years) | – | ||
 30–34 | 129 (25.0) | 132 (25.6) |  |
 35–39 | 129 (25.0) | 128 (24.8) |  |
 40–44 | 129 (25.0) | 128 (24.8) |  |
 45–49 | 129 (25.0) | 128 (24.8) |  |
Ethnicity (US only) | – | ||
 European Americans (white) | – | 358 (69.4) |  |
 African Americans | – | 24 (4.7) |  |
 Hispanic and Latinx Americans | – | 47 (9.1) |  |
 Asian Americans | – | 38 (7.4) |  |
 Native Americans | – | 30 (5.8) |  |
 Others | – | 19 (3.7) |  |
Educational status | |||
 Junior high/middle/high school | 157 (30.4) | 46 (8.9) | < 0.001 |
 College/vocational school | 127 (24.6) | 72 (14.0) |  |
 University/graduate school | 221 (42.8) | 388 (75.2) |  |
 Others/refusal to respond | 11 (2.1) | 10 (2.0) |  |
Employment status | |||
 Regular/full-time | 293 (56.8) | 378 (73.3) | < 0.001 |
 Part-time | 133 (25.7) | 71 (13.8) |  |
 Contract/dispatched | 50 (9.7) | 39 (7.6) |  |
 Freelancer | 34 (6.6) | 12 (2.3) |  |
 Others | 6 (1.2) | 16 (3.1) |  |
Shift type | 0.004 | ||
 Day-time shift | 450 (87.2) | 412 (79.8) |  |
 Rotation-shift | 55 (10.6) | 81 (15.7) |  |
 Night-shift | 11 (2.1) | 23 (4.5) |  |
Occupation | < 0.001 | ||
 Managerial | 41 (7.9) | 142 (27.5) |  |
 Professional/technical | 105 (20.3) | 221 (42.8) |  |
 Clerical | 162 (31.4) | 45 (8.7) |  |
 Sales/services | 73 (14.1) | 19 (3.7) |  |
 Transport | 14 (2.7) | 7 (1.4) |  |
 Production | 77 (14.9) | 12 (2.3) |  |
 Agriculture/forestry/fisheries | 5 (1.0) | 0 (0.0) |  |
 Others | 39 (7.6) | 35 (6.8) |  |