Sleep During Pregnancy: Why It Changes and How to Cope

Sleep problems are one of the most common complaints in pregnancy. Most pregnant people experience some degree of sleep disturbance, and it tends to be most pronounced in the third trimester. The good news: there are practical steps that help, and most sleep changes are normal and resolve after birth.

Why Sleep Changes During Pregnancy

Several overlapping factors disrupt sleep during pregnancy. Often more than one is at work at the same time.

Hormonal changes

Progesterone rises sharply in early pregnancy and is a potent sedative — it is the main reason many people feel exhausted and need more sleep in the first trimester. Later in pregnancy, hormonal shifts (including rising estrogen and progesterone) alter sleep architecture and can reduce restorative deep sleep.

Physical discomfort

As the uterus grows, finding a comfortable position becomes harder. Breast tenderness, back pain, and round-ligament pain all make it more difficult to settle and stay asleep.

Frequent urination

The uterus presses on the bladder, and the kidneys process more fluid during pregnancy. This means more trips to the bathroom, especially at night, and it often worsens in the third trimester when the baby's head engages.

Heartburn and reflux

Progesterone relaxes the lower esophageal sphincter, allowing stomach acid to rise. Lying flat makes reflux worse, so many people wake with burning or regurgitation.

Leg cramps and restless legs

Nocturnal leg cramps are common in the second and third trimesters. Restless legs syndrome also appears more often in pregnancy and can delay sleep onset.

Anxiety and racing thoughts

Worry about the baby, birth, and the life changes ahead is normal — and it is a well-documented cause of insomnia in pregnancy.

Sources: ACOG; Mayo Clinic; NHS.

Sleep Changes by Trimester

First Trimester (Weeks 1-13)

Fatigue is the dominant feature. Many people need significantly more sleep than usual and may nap during the day. Paradoxically, nausea and vomiting can still interrupt sleep. The overall pattern is often "sleepy but not well rested."

Second Trimester (Weeks 14-27)

For many, this is the most comfortable stretch of pregnancy. Energy often returns, nausea fades, and sleep may improve. Reflux and frequent urination can still interrupt nights, but the third-trimester sleep disruption has usually not yet begun.

Third Trimester (Weeks 28-40)

Sleep disturbance peaks here. A large uterus makes positioning difficult, reflux and frequent urination intensify, and the baby's movements can wake you. Insomnia is common, and total sleep time often drops even as the need for rest rises.

Sources: ACOG; NICHD; Mayo Clinic.

Safe Sleep Positions

Sleeping on your side — particularly the left side — is recommended in pregnancy, especially in the second and third trimesters.

Why side sleeping matters: lying on your left side improves blood flow and nutrient delivery to the placenta and baby, and it relieves pressure on the inferior vena cava — the large vein that returns blood to the heart and which the heavy uterus can compress when you lie flat on your back.

Avoid sleeping flat on your back in the third trimester. Research has linked going to sleep on the back in late pregnancy with an increased risk of stillbirth. The absolute risk remains small, but because the finding is consistent across multiple studies, guidance bodies advise settling to sleep on the side instead.

Practical tips for side sleeping:

• Use a pillow between your knees to align your hips and reduce back strain.
• Place a pillow under your belly for support.
• Use a pillow behind your back to keep you from rolling onto your back.
• A full-body pregnancy pillow can make side sleeping much more comfortable.
• If you wake on your back, simply roll onto your side — there is no need to worry.

Sources: ACOG; NHS; Auckland Stillbirth Study and subsequent research.

Tips for Better Sleep

• Stick to a schedule: Go to bed and wake at consistent times, even on weekends.
• Sleep on your side: Left side is best, but either side is fine.
• Use pillows strategically: Between the knees, under the belly, behind the back.
• Manage heartburn: Eat smaller meals, avoid lying down for 1-2 hours after eating, and elevate the head of your bed or use extra pillows.
• Time your fluids: Stay well hydrated during the day, but reduce fluids in the hour or two before bed.
• Move during the day: Gentle exercise (with your clinician's approval) improves sleep — just avoid vigorous activity close to bedtime.
• Wind down: Limit screens before bed, keep the room cool and dark, and try a calming routine.
• Limit caffeine: Especially in the afternoon and evening.

When to Talk to Your Clinician

Some sleep changes are normal, but certain symptoms deserve medical attention. Contact your healthcare provider if:

• Insomnia is severe or persistent and affecting your daily functioning
• You (or your partner) notice loud snoring, gasping, or pauses in breathing during sleep — this can indicate sleep apnea, which is more common in pregnancy and needs assessment
• Restless legs are frequent and unsettling
• You have symptoms of depression or anxiety, or persistent low mood
• You are concerned about your sleep for any other reason

Sleep apnea in particular is under-recognized in pregnancy. It is more likely in people with obesity or chronic high blood pressure, and it is associated with complications that benefit from treatment. If you suspect it, ask your clinician — it is worth raising rather than dismissing as "just pregnancy."