Table 3.

Associations between 6-sulfatoxymelatonin mesor and acrophase between day-only workers and shift workers on day and night shifts, stratified by chronotype and number of consecutive night shifts

Cosinor parameters
Mesor (95% CI)Acrophase (95% CI)
NCrude geometric mean (ng/mg)Adjusted mean % changeaCrude geometric mean (hh:mm)Adjusted mean difference (h)a
Day only, shift work night
 Day (only)b14715.4 (14.1, 16.7)Ref4:23 (4:11, 4:36)Ref
 Night (rotation)11413.6 (11.3, 15.9)c−25.0 (−37.7, −9.8)d3:43 (3:20, 4:06)−0.5 (−1.0, −0.05)d
  Chronotype (MSF)
   Early3814.4 (9.9, 18.9)−22.1 (−39.3, −0.6)d4:01 (21:44, 5:58)−0.2 (−0.8, 0.3)
   Middle3812.1 (9.7, 14.4)−24.7 (−40.6, −4.7)d3:54 (22:03, 5:51)−0.5 (−1.0, 0.09)
   Late3814.4 (9.5, 19.2)−30.6 (−46.8, −9.2)d3:14 (20:53, 5:59)−0.9 (−1.5, −0.2)d
  Number of consecutive nights
   <36814.3 (11.5, 17.1)−19.7 (−34.3, −1.7)d3:46 (3:17, 4:16)−0.6 (−1.1, −0.07)d
   ≥34612.6 (8.6, 16.5)c−32.8 (−47.6, −13.8)d3:38 (3:01, 4:16)−0.6 (−1.2, −0.002)d
Day only, shift work day
 Day (only)b14715.4 (14.1, 16.7)Ref4:23 (4:11, 4:36)Ref
 Day (rotation)11415.2 (13.7, 16.7)−7.0 (−21.4, 0.74)4:31 (4:17, 4:45)0.2 (−0.2, 0.5)
  Chronotype (MSF)
   Early3814.3 (12.0, 16.6)−9.8 (−28.0, 12.9)4:47 (2:06, 5:58)0.5 (−0.006, 0.9)
   Middle3815.5 (12.5, 18.5)−4.5 (−24.4, 20.9)4:31 (0:03, 5:57)0.2 (−0.3, 0.7)
   Late3815.9 (13.3, 18.6)−9.2 (−29.3, 16.9)4:14 (1:09, 5:55)−0.1 (−0.7, 0.4)
  Number of consecutive nights
   <36816.7 (14.6, 18.7)0.6 (−16.8, 21.7)4:30 (4:13, 4:47)0.09 (−0.3, 0.5)
   ≥34613.1 (11.1, 15.1)−19.7 (−36.0, 0.7)4:32 (4:07, 4:57)0.3 (−0.2, 0.8)
  • aAdjusted models controlled for cumulative shift work, age, education, parity, age of first birth, and use of sleep aid.

  • bReference group for all comparisons.

  • cP < 0.05 using the Wilcoxon rank-sum test.

  • dP < 0.05 using the Wald test.