Table 2

Characteristics of cases and controls, by phase shift (age period 15–19)

Phase shift between work/school and free days (hours)
<11–3>3
CasesControlsCasesControlsCasesControls
N12631927608914204332
Women, n (%)927 (73)1433 (74)436 (72)661 (72)139 (68)230 (71)
Swedish, n (%)1011 (80)1502 (78)472 (78)732 (80)157 (80)245 (76)
Sleep duration, hours/night (SD)8.0 (1.1)8.1 (1.0)8.1 (1.0)8.2 (1.0)8.0 (1.1)8.1 (1.2)
Sleep quality, mean value (SD)4.3 (0.9)4.4 (0.8)4.3 (0.9)4.4 (0.8)4.2 (1.0)4.3 (0.9)
Smoking, n (%)598 (47)752 (39)318 (52)405 (44)136 (67)164 (51)
Mean sun exposure (SD)6.1 (1.8)6.5 (1.9)6.5 (1.7)6.6 (1.8)6.2 (1.8)6.6 (1.9)
Mean adolescent BMI, kg/m (SD)22.5 (3.9)21.9 (3.2)22.7 (3.8)21.9 (3.4)22.8 (4.3)22.4 (4.2)
Infectious mononucleosis, n (%)220 (17)193 (10)114 (19)95 (10)47 (23)49 (15)
Age at disease onset (SD)36.0 (10.9)32.7 (9.9)33.9 (10)
  • Sleep quality was assessed on a 5-grade scale (1=lowest quality, 5=highest quality).

  • BMI, body mass index.