For those of us who sometimes have problems sleeping, I found a really good book. It's called "The Well-Rested Woman: 60 Soothing Suggestions for Getting a Good Night's Sleep"
by Janet Kinosian. It goes into great detail about how we sleep, what things affect it, and tips for getting a good night sleep. I found it on Amazon.com for about $10. It's written for women and discusses hormonal issues that can affect sleep.