According to IMS Health, a health care consulting firm in Danbury, Conn., the use of prescription sleep aids among women peaks from 40 to 59. Last year, the firm said, 15,473,000 American women between those ages got a prescription (overwhelmingly for Zolpidem, the generic form of Ambien) to help them sleep, nearly twice the number of men in that age group.

Those figures do not include those who are prescribed anti-anxiety or anti-depressant medications, frequently used off-label for insomnia. Nor do they include women who zone out with a glass of wine.

They also do not take into account the many women who have no trouble passing out at 10 p.m. - but zing wide awake at 3:30 a.m. with thoughts like those of Anne Kimball, 46, a mother in Oxford, Pa., as she runs “down the menu, from kid to kid”: “Did I send in the permission slip by deadline? Should I chaperone the field trip? Am I green enough?”

Or those of Susan Stoga, a mother of two in Barrington, Ill.: “Did I send that e-mail to my client? Is the permission slip for pictures due today? Do Carrie’s dance shoes still fit? Is Girl Scouts on this week?”

“Stupid stuff, when it comes down to it,” said Ms. Stoga, 46.

Meg Wolitzer, 52, a novelist who half-jokingly named her blog “Written on Ambien,” said: “Waking up in the middle of the night is the problem of every woman I know. The minute I had children I was like the mother listening in the woods for the bear. I don’t know if men are less vigilant, but my husband doesn’t wake up in the middle of the night. He could sleep in a dunking booth.”

Many mothers “never back off the vigilance,” said Dr. Katherine M. Sharkey, a sleep-medicine expert at the Sleep for Science Research Lab at Brown University. A female patient will come in complaining of insomnia, Dr. Sharkey said, and when asked how long she’s had it, the patient will say, “Fifteen years - ever since my baby was born.”

ONE of the great untruths of modern parenthood is that children - with their runny noses, lost teddies, nightmares real and faux - are largely to blame for mothers’ lack of sleep; that women are all like Christina Applegate in the sitcom “Up All Night,” cutely wan from their infant’s 2 a.m. feedings. But here is the reality: it is the mothers who keep themselves awake.

“There’s no release valve to let things fall by the wayside during the day, and that’s creeping into women’s nights,” Dr. Sharkey said. “So they’re waking up in the middle of the night with a million things running through their heads: things that may not be earth shattering, but it’s real stuff and it causes serious sleep deprivation.”

Dr. Meir Kryger, director of sleep medicine research and education at Gaylord Hospital in Wallingford, Conn., said women “are really paying the price in sleep for their current role in society.” Given their often-dueling roles as both a breadwinner and primary caregiver, “they have way more problems with insomnia.”

Some women blame their own perfectionism.

“A lot of women I see don’t prioritize,” said Shelby Harris, director of the Behavioral Sleep Medicine Program at Montefiore Medical Center in the Bronx. “Is it important to have dinner on the table at night? Yes. Must it be a five-course meal? Absolutely not.”

Ana Maria Alessi, 50, a single mother from Maplewood, N.J., who works full time, is a 3 a.m. waker.

“I think so much of what drives it is our need for control,” she said. “We feel like it’s our job to anticipate any variant on The Day, much less The Life - If it rains will I need to change my schedule so I can drop off my kid and he doesn’t need to ride his bike in a downpour? We try to ward off anything that can interfere with the Good Day.”

Ms. Wolitzer, the novelist, sees a disconnect between women’s day and night selves, with no sensible transition.