Table 4.

Results from regression analyses of nocturnal melatonin and reproductive hormone levels during nighttime work (night shift worker), relative to nighttime sleep (day shift worker), all participants (n = 151 day and 170 night shift workers)

Urinary hormonea% increase (+) or decrease (−) in NSW hormone levels, relative to DSW levelsb95% confidence interval
6-Sulfatoxymelatonin−68.6%c(−74.8% to −62.5%)
FSH+35.0%d(+0.6% to +69.4%)
LH+37.7%d(+2.6% to +72.8%)
E1C+7.2%(−3.3% to +17.8%)

Abbreviations: DSW, day shift workers; NSW, night shift workers.

  • aAnalyzed using the natural log transformation.

  • bAdjusted for the effects of age, hours of darkness, BMI, number of pregnancies, number of alcoholic beverages consumed, and use of psychotherapeutics.

  • cP < 0.0001, using 2-sided t test.

  • dP < 0.05, using 2-sided t test.