There was an interesting article 7/3/08 in Ms.Magazine by Gayle Greene suggesting that trouble sleeping may be related to fluctuating hormones, which can be more difficult to deal with than usual, at several particular points in a woman's life. In particular, Ms. Greene reported that twice as many women have trouble sleeping than men and that about 67% of women report frequently having trouble sleeping.
Of course, we know that stress can lead to insomnia, as can being poor, subjected to violence, being hot, or eating or exercising too close to bedtime. However, Ms. Greene suggests that we also sleep worse when our hormones are fluctuating - at menarche, during puberty when surges of estrogen and progesterone occur, and the estrogen increases cortisol levels, promoting a stress response, before our periods start, after childbirth, and during menopause.
One way that the fluctuating hormones impact sleep is because changes in hormone levels make us hot - hot flashes for sure, but did you know that women with PMS have higher body temperatures, as do women taking birth control pills?