New mothers lose an average of seven hundred hours of sleep in the first year postpartum.
…In one study, mother rats were given the opportunity to press a bar and get a squirt of cocaine or press a bar and get a rat pup to suck their nipples…Those oxytocin squirts in the brain outscored a snort of cocaine every time.
Both are from the new and noteworthy The Female Brain, by Louann Brizendine. Here is a very brief (and somewhat skewed in the direction of politically correct) summary. Here is more. Here is a Deborah Tannen review.
There are way way way too many books on gender differences. Most of them just string together the usual well-known templates, but I read every page of this one with interest. The best parts focus on the role of hormones.
Not everyone will appreciate the punchy style — "There’s a new reality brewing in Sylvia’s brain, and it’s a take-no-prisoners view" — but everyone who wants to marry or have kids should read this book.