Most adults need seven to nine hours of sleep, but during pregnancy the recommendation increases to eight to ten hours per night. That extra hour or two isn’t just about feeling less tired. Sleep plays a direct role in blood pressure regulation, blood sugar control, and fetal development, making it one of the most impactful things you can do for a healthy pregnancy.
Why You Need More Sleep During Pregnancy
Pregnancy dramatically shifts your hormonal landscape, and those shifts change how your brain regulates sleep. Progesterone, which rises steadily throughout pregnancy, has strong sedative effects. It increases the duration of deep sleep and shortens the time it takes to fall asleep. Estrogen, meanwhile, reduces the amount of dream-stage (REM) sleep you get. The net result is that your body is pushing you toward more sleep while simultaneously making that sleep less efficient and more fragmented.
Your body is also doing enormous physical work: expanding blood volume by nearly 50%, building a placenta, and supporting rapid fetal growth. All of this increases your baseline energy demand. The eight-to-ten-hour recommendation accounts for the fact that even if you’re in bed that long, you’re unlikely to get solid, uninterrupted sleep for all of it.
How Sleep Changes Across Trimesters
First Trimester
Sleep problems typically start here. Rising progesterone can cause intense daytime drowsiness, even if you slept a full night. You may find yourself needing naps for the first time in years. At the same time, deep sleep decreases compared to pre-pregnancy levels, and overall sleep efficiency drops. Frequent urination, nausea, and breast tenderness contribute to nighttime wake-ups. Many women describe feeling exhausted but unable to sleep well, a frustrating combination driven almost entirely by hormonal changes rather than anything they’re doing wrong.
Second Trimester
Most women get a brief reprieve. Deep sleep stages partially recover compared to the first trimester, and daytime sleepiness often eases. But by the late second trimester, around weeks 23 to 24, total nighttime sleep starts to fall. Heartburn (gastroesophageal reflux) becomes a more common sleep disruptor as the growing uterus pushes against the stomach.
Third Trimester
This is when sleep becomes genuinely difficult. The majority of women report significant sleep disturbances in the third trimester. Back pain, frequent urination, fetal movements, heartburn, and leg discomfort all interrupt sleep throughout the night. Both deep sleep and REM sleep decrease, replaced by lighter, more easily disrupted sleep stages. You’ll spend more time awake after falling asleep than in earlier trimesters. Interestingly, total sleep time (including naps) often rebounds to roughly pre-pregnancy levels during this period, suggesting your body compensates by pushing you to rest during the day.
What Happens When You Don’t Get Enough
Consistently sleeping fewer than six hours per night during pregnancy carries real health risks, particularly for preeclampsia, a dangerous high blood pressure condition. One study of 576 pregnant women found that those sleeping fewer than six hours had roughly seven times the risk of developing preeclampsia after adjusting for other factors. Women who took a long time to fall asleep had about 4.5 times the risk. Poor overall sleep quality was linked to nearly six times the risk.
A separate cohort study found even more striking numbers: women sleeping fewer than five hours in early pregnancy were about nine times more likely to develop preeclampsia later. Sleep-disordered breathing, including snoring and sleep apnea, has also been associated with more than double the risk.
Beyond preeclampsia, short sleep during pregnancy has been linked to gestational diabetes, longer labor, and higher rates of cesarean delivery. These aren’t small, theoretical risks. They’re among the most common serious pregnancy complications, and sleep duration is one of the few modifiable factors involved.
Can You Sleep Too Much?
There is some evidence that very long, uninterrupted sleep may also carry risks. A Michigan Medicine-led international study found that sleeping more than nine hours per night in the third trimester was associated with late stillbirth (after 28 weeks). The study compared 153 women who experienced stillbirth with 480 women who had live births and found that lengthy periods of undisturbed sleep were a risk factor independent of other variables.
This doesn’t mean you should set an alarm to avoid oversleeping. The concern appears to be about prolonged, unbroken sleep rather than total hours, and most women in the third trimester are already waking multiple times per night. If you consistently sleep ten or more hours without waking, it’s worth mentioning to your provider.
Sleep Position After 30 Weeks
You’ve probably heard that left-side sleeping is best during pregnancy. The reasoning is straightforward: as the uterus grows heavier, lying on your back can compress the major blood vessels that supply your lower body and return blood to your heart, potentially reducing blood flow to the placenta.
An NIH-funded study clarified the timeline for this concern. Through 30 weeks, sleeping on your back or either side does not appear to increase the risk of stillbirth, reduced fetal size, or preeclampsia. The researchers specifically noted that their findings apply only through week 30 and don’t address late pregnancy, where previous studies have linked back sleeping with higher stillbirth risk.
The practical takeaway: don’t stress about sleep position in the first two trimesters. After 30 weeks, favoring your left side is a reasonable precaution, though right-side sleeping is also fine. If you wake up on your back, simply roll to your side. Placing a pillow behind you can help you stay in position through the night.
Restless Legs and Other Sleep Disruptors
Between 10 and 34% of pregnant women develop restless legs syndrome, a condition that causes an uncomfortable, nearly irresistible urge to move your legs, especially at night. It tends to worsen in the third trimester and usually resolves within weeks of delivery. Iron deficiency, which is common in pregnancy, appears to be a contributing factor, so maintaining adequate iron intake may help.
Sleep apnea also becomes more common during pregnancy. Rising progesterone decreases muscle tone in the upper airway, and weight gain can further narrow the airway. Snoring that’s new during pregnancy, or that’s accompanied by gasping or daytime exhaustion despite adequate sleep time, is worth discussing with your provider. Sleep apnea during pregnancy has been linked to roughly double the risk of preeclampsia.
Practical Ways to Improve Sleep
The sleep hygiene basics that work outside of pregnancy still apply, but a few strategies are especially relevant when you’re expecting. For heartburn, which disrupts sleep for a large percentage of pregnant women in the second and third trimesters, eating your last meal at least two to three hours before bed and elevating your upper body slightly with pillows can make a meaningful difference.
A body pillow or wedge pillow between your knees and under your belly reduces the hip and lower back pressure that wakes many women in the third trimester. Keeping your bedroom cool matters more during pregnancy because your basal body temperature is already elevated. Many women find that a room temperature around 65 to 68°F helps them stay asleep longer.
Naps are not a sign of failure. If you’re unable to get eight full hours at night, a 20-to-30-minute nap in the early afternoon can partially compensate without interfering with nighttime sleep. Your body is already pushing you toward daytime rest, particularly in the first and third trimesters, and fighting that urge doesn’t earn you better sleep later.
For women considering melatonin supplements, the evidence so far is cautiously reassuring. Clinical trials have used doses ranging from 8 to 30 mg daily during pregnancy without reported adverse effects to mothers or babies, and melatonin does cross the placenta easily. Over-the-counter doses of 1 to 10 mg are well below what’s been tested in trials. That said, research on melatonin in pregnancy is still limited, so it’s best used as a short-term option rather than a nightly habit, and only after checking with your provider.