If you ask new moms how much sleep they need to function, many will say that five hours a night is at least enough to make them feel human.
"Sleep is sort of the holy grail for news moms," says Pam Gahr, mother of a 4-month-old daughter.
Without proper amounts of sleep, people feel fuzzy and impatient. These drawbacks of too little sleep are well documented.
Gahr is getting more than five hours of sleep per night.
"I think six or seven hours is really what I need, definitely," she says.
Connection Between Sleep and Weight
Scientists now have evidence that lack of sleep makes it harder to take off baby weight after giving birth.
"This is the first time it's really been shown," says obstetrician Tracy Flanagan, director of women's health at Northern California Kaiser Permanente.
In a study of about 940 new mothers, researchers discovered that moms who were sleeping five hours or less when their babies were 6 months old were much more likely to retain baby weight, compared with women sleeping at least seven hours a night.
"The difference of two hours," Flanagan says, "which may not sound like a lot of sleep, made a substantial impact on whether women could shed their weight."
Many of the mothers who slept at least seven hours returned to within a pound or two of their pre-pregnancy weight.
In contrast, the more sleep-deprived moms were three times as likely to hang on to 11 pounds or more of their baby weight.
This amount of extra weight can be unhealthy, especially because many women carry it right around the middle of their bodies. Women wind up having, for example, lower levels of HDL cholesterol, which is a risk factor for heart disease, explains Matthew Gillman of Harvard Medical School.
"So that's why, for the long term, it's important for women to try to retain as little of the extra weight after pregnancy as possible," he says.
The study found this weight-sleep correlation held up for first-time mothers and for women who had more than one child. The findings fit with a growing body of evidence that suggests sleep and obesity are related throughout life.
"What some experimental studies are showing is that the less sleep one gets, the more the body puts out hormones that tend to increase the weight," Gillman says.
Doctors Advise More Sleep
The research findings are significant enough, says Dr. Tracy Flanagan, "that I might say to my patients, more emphatically, to seek out ways to get more sleep."
One strategy, experts say, is to scale down late-night activities when possible.
This is a challenge for many moms. Gahr, who has managed to take off all her baby weight and get the sleep she needs, says she uses evenings to cross things off her to-do list.
"I tend to answer e-mails. Sometimes I clean the kitchen if it's really a mess."(A task she'd gladly hand over, she says.)
But it seems that multitasking and mothering go hand in hand.