The money men make from their willingness to work the least desirable hours is not a sign of discrimination against women, but a sign of the willingness of mostly married men to lose sleep to support the family as their wife loses sleep to feed the child. A willingness to do the uncomfortable shifts is one reason married men earn more than twice what never-married men earn. Men's contribution, made at night, need not be lost in the dark.

p. 69. - Why Men Earn More (2005)