Sleeping for Two: Sleep Changes During Pregnancy

Pregnant woman sleeping
Mothers-to-be should spend at least eight hours in bed each night so they can get at least seven hours of sleep. (Image credit: Click Images | Shutterstock)

Being pregnant can be a tiring experience for a woman's body. Both the physical discomforts of pregnancy as well as the emotional stress of this major life change can cause sleep problems and keep a mother-to-be awake at night. 

People may joke that the difficulty many pregnant women have sleeping is merely preparing them for the lack of sleep they will experience when the baby finally arrives. All kidding aside, pregnancy is a good time for women to take their sleep needs more seriously and make an effort to get more of it. 

Feeling exhausted is a common complaint, especially during the first and third trimesters. But women might be caught off guard by how worn out they feel in the early months of pregnancy. 

"A lot of women are totally surprised by how fatigued they feel during the first trimester," said Kathy Lee, a professor of nursing at the University of California San Francisco, who has studied how pregnancy affects sleep. 

Women know about morning sickness in early pregnancy, but many first-time mothers say they had no idea about how tired they often feel at this stage, Lee said. 

Sleeping for two

Similar to the advice that a pregnant woman should be "eating for two," health professionals should also be emphasizing the importance of "sleeping for two" during prenatal visits, Lee told Live Science. 

One reason is that pregnancy can affect both the quantity of sleep a woman gets as well as the quality of it.

As their body changes and pregnancy discomforts make it more difficult to fall and stay asleep, Lee recommended that mothers-to-be spend at least 8 hours in bed each night so they can get at least 7 hours of sleep.

Researchers have found that not getting enough sleep during pregnancy could affect a woman in ways that go beyond feeling exhausted during the day, being irritable and having poor concentration. 

One of Lee's studies found that first-time mothers who got less than 6 hours of sleep at night were 4.5 times more likely to have a C-section and their average length of labor was 10 hours or longer compared with first-time mothers who slept 7 hours or more. 

"A woman really needs to go to bed earlier when she is pregnant," Lee said. Women need the extra rest, and they can't keep going on the same amount of sleep they got before becoming pregnant, she pointed out. 

Pregnancy and fatigue

Researchers are still trying to figure out the exact reasons why pregnancy causes a woman to feel so exhausted, Lee said. 

But to some extent, pregnancy-related fatigue is hormonal, she said. In the early phases of pregnancy, progesterone levels start to increase. 

"Progesterone is a hormone that slows a woman down and mellows her out, and some women may perceive these effects as fatigue," Lee said. 

Besides the influence of hormones, some of the sleepiness that women feel early in pregnancy could also be physiological as the uterus gets bigger and the fetus grows, coupled with pregnancy-related weight gain and fluid accumulation in the body, Lee said. These changes mean the body is working harder as the placenta forms to nourish the developing fetus, the blood supply increases and the heart beats faster. 

And emotional factors can also play a role. The excitement and anticipation of having a baby as well as the fears of impending motherhood and the anxiety about labor and delivery can all be stressful and make a woman feel more tired than usual. 

Here's what to expect in terms of sleep changes during the three stages of pregnancy. 

Sleep and the first trimester 

In the early months of pregnancy, rising progesterone levels may not only make a woman feel drowsy, but they may also be partly to blame for the frequent need to pee, which can also disrupt sleep and worsen sleepiness. 

During the first trimester, the hormones leading to the bladder get sluggish, which increases a woman's urine production. This can cause her to wake up and need to go to the bathroom more frequently at night, Lee explained. 

To reduce their nightly bathroom visits, women who are expecting should not cut back on drinking plenty of fluids during the day because water and other liquids are important to help prevent constipation and excessive swelling, two common pregnancy discomforts. But they might cut back on fluids in the evenings. 

During those nightly bathroom trips, women should rely on a nightlight rather than turning on a bright bathroom light, which could make it harder to fall back to sleep. 

Another factor that can rob a woman of the shuteye she needs is the nausea known as morning sickness, which can happen any time of the day or night. To relieve the queasiness, some women eat crackers or dry cereal before getting out of bed in the morning. 

A woman's breasts may also feel more sore and tender during pregnancy, making it challenging or uncomfortable to sleep on her stomach, if that's her preferred position. 

Women might also feel warm or hot when they sleep during pregnancy because of an increased metabolic rate, Lee said. A fan is often nice to keep a woman cooler, she said, plus it has the added benefit of blocking out noise inside and outside the bedroom, including a snoring bed partner. 

However, bed mates are not the only ones who might be snoring. Snoring is a common occurrence during pregnancy, and it can start in the first trimester in women who are already overweight or have allergies, Lee said. 

Because of the many possible disruptions to sleep during pregnancy, napping is a good idea as long as a woman can fall asleep at night, Lee said. 

But avoid using sleeping pills or even sleep-inducing supplements, such as melatonin, during pregnancy, Lee said. "Most women are too afraid to take them," she added. 

Sleep and the second trimester

The second trimester of pregnancy is usually the best for women, Lee said. "Everything levels out and things aren't changing quite as fast." 

Lee explained that hormonal changes, which are steep during the first trimester, level off during the second trimester, and then are steep again in the third trimester.  

Leg cramps might occur at night during the second trimester. And some pregnant women, especially if they anemic and have low iron levels, may experience restless legs syndrome beginning in the evening hours of the second trimester and becoming more severe in the third trimester, Lee said. This condition, in which the the legs feel jumpy like they have ants crawling up and down their veins, can occur while sitting or lying down and might be extremely uncomfortable. 

Often the only relief from the pain is from walking around, Lee said, but then a woman might not be able to fall back asleep. 

Heartburn is another problem that can keep women awake at night. As pregnancy progresses and a woman's uterus gets bigger, it may press on her stomach making a burning sensation more common. 

Sleeping on the left side with the knees bent may be a better position for women who are experiencing heartburn during pregnancy, Lee said. Some women may also try sleeping with the head of their bed elevated or by propping their head on more pillows to ease the acid backwash of heartburn. 

A lot of women say they have bizarre dreams related to their baby during pregnancy, Lee said. Although many women report strange dreams, the results from her research did not show any differences in dreaming across the trimesters compared with dreaming before a woman becomes pregnant. 

"It might be that women are able to remember their dreams better during pregnancy because they are waking up more often," Lee told Live Science. 

Sleep and the third trimester

One study suggests that in late pregnancy, women report that the overall quality of their sleep suffers, they have more trouble falling asleep, and their number of nighttime and early morning awakenings increase compared with mid-pregnancy. 

As a woman's belly increases in size and the fetus is getting bigger and more active, Lee suggested that pregnant women sleep in any comfortable position they can find. 

But she advised mothers-to-be to stay off their backs as much as possible because a heavy uterus can press on nerves in the spine and on a major vein (the inferior vena cava) that carries blood between the lower body and heart.

The National Sleep Foundation recommends that pregnant women should sleep on their left side, which may improve the flow of blood and nutrients to the developing fetus and to a woman's heart, uterus and kidneys. 

Use pillows to be more comfortable placing one between the knees, a second under the belly, and a third behind the back to support it and relieve pain, Lee advised. 

Snoring is also a more common occurrence in the third trimester of pregnancy as a result of weight gain and more nasal congestion, Lee said. She recommended that women who have stuffy noses use nasal strips to help open up their nasal passages and improve their night-time breathing.

One study found that women who began snoring while pregnant may be at greater risk of pregnancy-related high blood pressure and preeclampsia, a condition of high blood pressure during pregnancy, compared with mothers-to-be who did not snore.  

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Live Science Contributor

Cari Nierenberg has been writing about health and wellness topics for online news outlets and print publications for more than two decades. Her work has been published by Live Science, The Washington Post, WebMD, Scientific American, among others. She has a Bachelor of Science degree in nutrition from Cornell University and a Master of Science degree in Nutrition and Communication from Boston University.