Table 6.

Results from regression analyses of nocturnal melatonin and reproductive hormone levels during nighttime work, relative to nighttime sleep, all night shift workers (n = 172 night sleep and 170 night work measurements)

Urinary hormonea% increase (+) or decrease (−) in NW hormone levels, relative to NS levelsb95% confidence interval
6-Sulfatoxymelatonin−47.3%c(−54.5% to −40.0%)
FSH+23.4%d(+1.6% to +45.1%)
LH+20.9%d(−0.4% to +42.2%)
E1C+12.8%d(+6.1% to +19.4%)

Abbreviations: NS, nighttime sleep; NW, nighttime work.

  • 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.