Sleep During Pregnancy: Challenges, Disorders, and Safe Solutions

Poor sleep during pregnancy is nearly universal — studies suggest that over 75% of pregnant women report significant sleep disturbance, making it one of the most common complaints of pregnancy. But poor sleep is not simply an inconvenience to endure. Both maternal sleep deprivation and specific pregnancy-related sleep disorders carry real health implications for mother and baby, and many are treatable with appropriate, safe interventions.

Why Pregnancy Disrupts Sleep: The Physiology

Pregnancy involves extensive physiological change that interacts with nearly every aspect of the sleep system:

• Progesterone: Rises sharply in the first trimester, causing profound fatigue, sedation, and increased total sleep time during the day — but also more fragmented and lighter night-time sleep. Progesterone also relaxes smooth muscle throughout the body, including in the upper airway (contributing to snoring) and the oesophageal sphincter (contributing to reflux).
• Estrogen: Contributes to nasal oedema (swelling of nasal passages) that worsens throughout pregnancy, increasing nasal congestion and nasal resistance — a significant factor in snoring and sleep-disordered breathing.
• Uterine expansion: As the uterus grows, it progressively compresses the diaphragm, reduces functional residual lung capacity, displaces the stomach (worsening reflux), and makes comfortable positioning increasingly difficult.
• Increased cardiac output and metabolic demands: Elevate heart rate and increase the sensation of physiological arousal, particularly in the first and third trimesters.
• Fetal movement: Often peaks when the mother is lying still, frequently disrupting late-night and early-morning sleep.
• Anxiety and emotional processing: The psychological adjustments of pregnancy — fears about labour, the newborn, relationship changes, financial concerns — are significant drivers of insomnia.

Sleep by Trimester: What to Expect

First Trimester (Weeks 1–12)

Progesterone-driven fatigue causes many women to sleep more in total — but with poorer quality. Nausea may affect the ability to achieve comfortable rest. Frequent urination begins early as the kidneys increase filtration rate and the expanding uterus presses the bladder. Sleep efficiency falls despite increased fatigue.

Second Trimester (Weeks 13–26)

Often considered the most sleep-friendly trimester. Progesterone levels stabilise; first-trimester nausea typically resolves; the uterus is not yet large enough to significantly restrict sleep positions. Many women find sleep improves meaningfully in this period — though back pain, vivid dreams, and early fetal movements may begin to disrupt sleep.

Third Trimester (Weeks 27–40)

The most sleep-disrupted period. Physical challenges reach their maximum: difficulty finding a comfortable position, severe acid reflux in the supine position, frequent urination (now from both increased filtration and direct bladder compression), significant back and hip pain, leg cramps, and fetal movement. Sleep-disordered breathing worsens as airway oedema and abdominal pressure reach their peak. Sleep efficiency and total sleep time typically fall to their lowest points.

Sleep Disorders During Pregnancy

Restless Legs Syndrome

RLS — the uncomfortable urge to move the legs, worst at rest and in the evening — affects up to 26–30% of pregnant women, making pregnancy one of the strongest risk factors for RLS. The condition typically emerges in the second or third trimester and resolves within the first month postpartum in most cases.

The primary driver of pregnancy-related RLS is iron and/or folate deficiency. Checking serum ferritin (not just haemoglobin) is essential — ferritin below 75 mcg/L is associated with RLS in pregnancy, and iron supplementation often produces dramatic improvement. Many prenatal vitamins contain iron, but additional supplementation may be needed if levels are low.

Dopamine agonists (the usual pharmacological treatment for RLS) are not routinely recommended during pregnancy due to limited safety data. Non-pharmacological approaches — heat, massage, gentle exercise, reduced caffeine — are first-line.

Obstructive Sleep Apnea

OSA develops or worsens during pregnancy in a significant proportion of women — particularly those with pre-existing obesity, multiple pregnancy, pre-eclampsia risk factors, or nasal congestion. The prevalence of OSA in the third trimester may be as high as 10–15% in the general pregnant population and substantially higher in women with obesity.

Untreated OSA in pregnancy carries meaningful clinical risks: gestational hypertension, pre-eclampsia, gestational diabetes, foetal growth restriction, and preterm delivery are all associated with inadequately treated sleep-disordered breathing. Screening for OSA (particularly in high-risk women) is increasingly recommended.

Treatment with CPAP during pregnancy is safe, effective, and is associated with improved pregnancy outcomes. Many women experience remission of OSA postpartum as hormonal oedema resolves and body weight returns toward baseline — a reassessment sleep study is appropriate postpartum.

Insomnia

Insomnia is extremely common throughout pregnancy. First-trimester anxiety, third-trimester physical discomfort, and postpartum anticipatory anxiety all drive significant sleep-onset and sleep-maintenance difficulties. The treatment of choice is CBT-I — as effective during pregnancy as in non-pregnant populations and completely safe. Most sleep medications are not recommended during pregnancy.

Sleeping Position in Pregnancy

Side sleeping — particularly on the left side — is recommended from approximately 28 weeks onwards. In late pregnancy, the supine (back-lying) position allows the weight of the uterus to compress the inferior vena cava, the major vein returning blood to the heart. This can reduce venous return and cardiac output, causing maternal dizziness and lightheadedness, and may reduce placental blood flow.

Studies have associated late third-trimester supine sleep with elevated stillbirth risk, though the absolute risk is small and the mechanism continues to be investigated. Women who wake and find themselves on their back should simply roll to the side — there is no benefit from deliberate sleep deprivation to avoid this position, and anxiety about sleep position itself is counterproductive.

Practical aids for side sleeping: pregnancy body pillows (supporting the abdomen, back, and knees simultaneously), placing a pillow behind the back to prevent rolling, and elevating the upper body slightly for reflux relief.

Postpartum Sleep

The postpartum period brings its own distinct sleep challenges. Newborn feeding and care create mandatory fragmented sleep — typically 4–5 hours total in highly disrupted blocks, which is the pattern that most drives postpartum fatigue, mood symptoms, and the development of clinical insomnia.

Postpartum insomnia — the inability to fall asleep even when the baby is sleeping — is a significant clinical entity, particularly in women with prior insomnia vulnerability or postpartum depression. CBT-I adapted for the postpartum period is effective and is an important tool for preventing acute postpartum sleep disruption from evolving into chronic insomnia disorder.

Sleep apnea that developed during pregnancy may or may not persist postpartum — a reassessment study several months after delivery is the appropriate approach rather than assuming either resolution or persistence.

References

• Mindell JA, Cook RA, Nikoloyski J. Maternal sleep and sleep disorders during the peripartum period. Sleep Medicine Clinics. 2015;10(1):53–59.
• Bourjeily G, Raker CA, Chalhoub M, Miller MA. Obstructive sleep apnea in pregnancy: a review. Chest. 2010;137(3):619–629.
• Picchietti DL, et al. Restless legs syndrome in pregnancy: prevalence, impact and management challenges. Therapeutics and Clinical Risk Management. 2017;13:1389–1397.
• American College of Obstetricians and Gynecologists. Sleep Disorders During Pregnancy. Committee Opinion 650; 2015.