Table 5.

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

Urinary hormonea% increase (+) or decrease (−) in DS hormone levels, relative to NS levelsb95% confidence interval
6-Sulfatoxymelatonin−37.5%c(−47.8% to −77.2%)
FSH+50.7%c(+27.0% to +74.3%)
LH+46.2%c(+20.4% to +72.0%)
E1C+8.3%d(+2.0% to +14.7%)

Abbreviations: DS, daytime sleep; NS, nighttime sleep.

  • 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 < 0.001, using 2-sided t test.

  • dP < 0.01, using 2-sided t test.