Pregnant? Sleep Well for Good Blood Pressure
< Oct. 06, 2010 > -- Getting enough sleep can be difficult when you re pregnant, but a new study says adequate sleep during those nine months may help keep your blood pressure normal.
Women who got less than six hours of sleep a night in early pregnancy had systolic blood pressure readings in their last trimester nearly 4 millimeters of mercury (mm/Hg) higher than women who slept nine hours nightly, the study found. (Systolic pressure is the top number in a blood pressure reading.) Women who got less than five hours of sleep increased their odds of developing preeclampsia - a serious pregnancy complication related to high blood pressure - more than ninefold.
"Women, in general, need about seven to nine hours of sleep during pregnancy, preferably nine hours. Getting less than that amount can have health affects," says study author Michelle Williams, Sc.D. Dr. Williams is a professor of epidemiology and global health at the University of Washington and co-director of the Center for Perinatal Studies at the Swedish Medical Center in Seattle.
Sleeping for two
"Women generally already know that they're eating well and getting enough exercise for two during pregnancy. Our study suggests that women should also aspire to sleep well for two," she says.
The study, published in the October issue of the journal Sleep, followed 1,272 healthy pregnant women recruited for the study during prenatal care visits to the Swedish Medical Center between December 2003 and July 2006.
Length of sleep didn't appear to affect blood pressure levels in the first and second trimesters. But during the third trimester, women who slept less than six hours a night had an average systolic blood pressure that was 3.72 mm/Hg higher than women who slept nine hours. Even women who slept seven to eight hours a night had systolic blood pressure readings that were 2.43 mm/Hg higher than women who slept nine hours.
Getting too much sleep also appeared to be a problem: Women who slept more than 10 hours a night in their first trimester had more than a twofold increase in the risk of developing preeclampsia.
Body rhythm changes
Dr. Williams says the study wasn't designed to find the cause behind these associations, but she theorizes that when sleep changes occur during pregnancy, they may affect the body's circadian rhythm. These circadian rhythm changes may cause hormonal changes that affect blood pressure levels.
Circadian rhythm is a roughly 24-hour cycle that responds to light and dark in a person's environment.
Mary Rosser, M.D., an obstetrician and gynecologist at Montefiore Medical Center in New York City, says numerous changes occur during pregnancy that could affect blood pressure levels. Weight gain is one such change. Even if weight alone doesn't affect blood pressure levels, the extra weight could cause sleep apnea, which is known to raise blood pressure, she says.
But, Dr. Rosser adds, it's definitely a good idea for pregnant women to try to get a good night's sleep.
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Finding Your Way to Slumberland
Fluctuating hormones affect how well you sleep during pregnancy - and at other times during your life. In the first trimester, when your body is adjusting to abnormally high hormone levels, you may feel sleepier than usual, but you may also wake more frequently.
Sound sleep may be difficult by the third trimester because of the physical discomfort of carrying a baby. Some women also develop sleep disorders such as restless legs syndrome, snoring, or insomnia during pregnancy.
One important sleep booster is exercise. With your health care provider's OK, aim for 30 minutes of moderate-intensity exercise each day. For more snooze-inducing tips, try these from the National Sleep Foundation:
Always talk with your health care provider for more information.
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