Quick Answer: Insomnia affects up to 80% of women by the third trimester. First trimester insomnia is driven by hormones and nausea, second trimester by growing belly and leg cramps, third trimester by physical discomfort and frequent urination. Research in Sleep Health (Bjorvatn et al., 2018) confirms that bedroom habits and sleep environment are central to chronic insomnia management, which matters because most sleep medications are not considered safe in pregnancy. Talk with your midwife or OB before trying any supplement.
In This Guide
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Sleep in pregnancy is one of those things that changes before you're ready for it to. In the first weeks, you're exhausted but can't get comfortable. By the third trimester, you know the ceiling above your bed very well. According to a review published in Sleep Medicine Reviews, insomnia symptoms affect 25% of people in the first trimester and climb to nearly 80% by the third trimester.
This guide covers all three trimesters, because the causes and solutions change significantly at each stage. It also focuses on safe interventions, most sleep medications and supplements are not appropriate during pregnancy.
First Trimester: Hormones, Fatigue, and the Cruel Paradox
The first trimester insomnia paradox: you're often exhausted beyond description during the day, but sleep is fragmented and unrestorative at night. The cause is hormonal.
What's Happening Hormonally
Progesterone levels rise dramatically in early pregnancy. While progesterone has sedating properties (it's one reason for first-trimester fatigue), it also causes more frequent waking and lighter overall sleep. It increases body temperature slightly, which affects sleep architecture. Oestrogen fluctuations add to the disruption.
hCG (human chorionic gonadotropin), the hormone detected in pregnancy tests, rises steeply in the first trimester and is associated with nausea, itself a major sleep disruptor for many people.
Common First Trimester Sleep Disruptors
- Nausea and morning sickness: Despite the name, nausea in pregnancy can occur at any time of day or night. Waking nauseous at 2 a.m. is common in the first 12 weeks.
- Frequent urination: Starts earlier than most people expect. The kidneys filter more blood during pregnancy, leading to more urine production. This begins in the first trimester, not just the third.
- Breast tenderness: Can make finding a comfortable sleep position difficult, particularly for stomach sleepers.
- Vivid dreams: Many pregnant people report an increase in vivid, sometimes disturbing dreams beginning in the first trimester. This appears to be related to hormonal changes and increased REM activity.
- Anxiety: First-trimester anxiety, particularly around miscarriage risk, the pregnancy being real and healthy, and life changes, is common and can significantly disrupt sleep onset.
Pregnancy and Sleep Architecture
Studies indicate that pregnancy is associated with measurable changes in sleep efficiency, slow-wave sleep, and total sleep time beginning in the first trimester. According to the National Sleep Foundation, slow-wave (deep) sleep, the most restorative sleep stage, tends to decrease across all three trimesters, with the most significant reduction in the third. This explains why many pregnant people report feeling unrested even after 8 or 9 hours in bed. Research in Sleep Health (Bjorvatn et al., 2018) supports addressing modifiable factors (bedtime routine, light exposure, bedroom environment) before considering pharmaceutical options.
First Trimester Solutions
- Small, bland snacks before bed can reduce nighttime nausea (ginger tea, crackers)
- Limiting fluids in the hour before bed reduces nighttime urination frequency somewhat
- A consistent sleep schedule anchors circadian rhythm when hormones are disrupting natural cues
- Cognitive behavioural techniques for anxiety (journaling worries before bed, relaxation breathing) can reduce sleep-onset difficulty
Second Trimester: The Better Sleep Window (Usually)
The second trimester is often called the "honeymoon period" of pregnancy for good reason. Nausea typically subsides, energy improves, and sleep often improves alongside it. Many people sleep better between weeks 13 and 26 than at any other point in pregnancy.
However, new sleep disruptors emerge:
Second Trimester Challenges
- Growing belly: By the mid-second trimester, stomach sleeping becomes uncomfortable. Side sleeping becomes the default, and finding a position that supports the growing belly takes adjustment.
- Heartburn and acid reflux: The growing uterus puts increasing pressure on the stomach, and pregnancy hormones relax the lower oesophageal sphincter. Nighttime heartburn often begins in the second trimester and worsens through the third.
- Leg cramps: Nocturnal leg cramps (often in the calves) are common in the second trimester, particularly at night. Possible causes include stretching of the leg muscles under increased body weight and electrolyte changes. They're typically brief but can fully wake you from deep sleep.
- Restless Legs Syndrome (RLS): RLS, an uncomfortable urge to move the legs, typically worse at rest in the evening, becomes significantly more common during pregnancy. Research estimates that up to 20 to 30% of pregnant people experience RLS symptoms, compared to about 5% in the general adult population. Iron deficiency (common in pregnancy) and folate levels may contribute.
Second Trimester Solutions
- For heartburn: avoid eating within 2 to 3 hours of bed; elevate the head of the bed slightly (per Mayo Clinic guidance for GERD)
- For leg cramps: gentle calf stretches before bed, adequate hydration, discuss magnesium supplementation with your midwife or OB (often safe in pregnancy)
- For RLS: discuss with your healthcare provider, iron levels should be checked, as iron supplementation can significantly reduce pregnancy RLS in deficient patients
- Begin using a pregnancy pillow if belly support is becoming an issue, this pays off progressively more through the third trimester
Third Trimester: The Full Picture
Third trimester insomnia is where the disruption peaks. Most of the second trimester issues intensify, and new ones appear:
- Physical discomfort: Back pain, hip pain, rib discomfort from the baby's position, and general difficulty finding any position comfortable
- Frequent urination escalates: The baby's head drops into the pelvis in preparation for birth, increasing direct bladder pressure. Bathroom trips of 2 to 4 times per night are common
- Fetal movement: Babies are often most active in the evening and night, and strong kicks can wake a light sleeper easily
- Shortness of breath: The uterus pushes up against the diaphragm, reducing lung capacity, particularly when lying flat
- Sleep apnea risk increases: Weight gain and nasal congestion in pregnancy may increase the risk of obstructive sleep apnea. New onset snoring in the third trimester should be mentioned to your OB, as untreated sleep apnea in pregnancy has been associated with gestational hypertension and other complications. A 2017 study in Sleep & Breathing (Souza et al.) found that 7.5-degree head-of-bed elevation reduced the apnea-hypopnea index by roughly 31%, which may help some pregnant patients managing positional snoring (confirm with your OB before adjusting any treatment)
- Anxiety about labour and delivery: The proximity of birth brings anticipatory anxiety that can significantly disrupt sleep onset
We have a full guide to third trimester insomnia specifically if you're in the final stretch and want more detail on that stage.
Safe Sleep Positions in Pregnancy
Our broader piece on the best sleeping position during pregnancy covers each trimester in detail. The guidance on sleep position has evolved over the past decade. Current recommendations from the Society of Obstetricians and Gynaecologists of Canada (SOGC) and comparable bodies globally:
Sleep Position Guidance
- Side sleeping (either side) is recommended from mid-second trimester onward. Left-side sleeping slightly improves blood flow to the uterus and placenta, but right-side sleeping is not harmful and the difference is small (we cover the trade-offs in left-side sleeping during pregnancy).
- Sleeping on your back is generally fine in the first and early second trimester. From roughly 20 weeks, prolonged back sleeping can compress the inferior vena cava (a major vein carrying blood back to the heart), which some research associates with reduced fetal blood flow. The risk is low and not definitive, but side sleeping is the standard recommendation from mid-pregnancy.
- If you wake up on your back, don't panic. Simply roll to your side. The research suggests the risk is associated with extended back sleeping, not rolling onto your back briefly during sleep.
- Stomach sleeping: Usually becomes uncomfortable before it becomes an issue. Once the belly is visible and present, stomach sleeping isn't practical.
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Mattress and Pillow Support During Pregnancy
The physical demands on your body during pregnancy change your sleep surface needs. Some considerations:
Mattress Firmness
A mattress that's too soft will allow the hips to sink too deeply during side sleeping, creating spinal misalignment and contributing to hip and back pain. A mattress that's too firm creates pressure point pain on the hips and shoulder. Most pregnant people sleep best on a medium to medium-soft mattress that cushions pressure points while providing enough support to keep the spine reasonably aligned during side sleeping.
If your current mattress is very old or very firm and hip/back pain is a significant issue, a mattress topper (2 to 3 inches of medium-density memory foam or latex) can provide pressure relief without replacing the mattress entirely.
Pregnancy Pillows
A full-body pregnancy pillow is one of the most effective interventions for pregnancy insomnia, particularly in the second and third trimester. It provides:
- Support for the growing belly (reducing the pull on lower back muscles)
- A wedge between the knees (reducing hip and lower back strain during side sleeping)
- Back support (preventing rolling to the back during sleep)
- Shoulder and neck support when used for the upper body
Types of pregnancy pillows and what they're best for are covered in our Best Pregnancy Pillows in Canada guide.
Brad, Owner, 40+ years of experience: "We've had many customers come in during the second trimester asking about mattresses because their back pain is keeping them up. Before recommending a full replacement, we always ask about their current setup and whether a good pregnancy pillow has been tried. Often a pillow change or a good topper solves it, though sometimes the mattress genuinely does need replacing."
Safe, Evidence-Based Solutions for Pregnancy Insomnia
| Approach | Evidence Level | Notes |
|---|---|---|
| CBT-I (Cognitive Behavioural Therapy for Insomnia) | Strong | The gold standard for insomnia; safe in pregnancy; some digital programs available in Canada |
| Consistent sleep schedule | Strong | Anchors circadian rhythm; effective across all trimesters |
| Pregnancy pillow use | Good | Particularly effective for physical comfort in second and third trimester |
| Moderate exercise (prenatal yoga, walking, swimming) | Good | Improves sleep quality; avoid vigorous exercise close to bedtime |
| Bedroom cooling (16–19°C) | Good | Pregnancy raises body temperature; cooler room supports sleep onset |
| Head-of-bed elevation (for heartburn) | Good | 15 to 20 cm elevation effective for nighttime reflux; adjustable base or bed risers |
| Melatonin supplementation | Insufficient evidence | Not recommended without OB guidance; insufficient safety data in pregnancy |
| Diphenhydramine (Benadryl) / Unisom | Generally considered safe short-term | Many OBs approve occasional use in pregnancy, ask your specific provider |
| Herbal teas (chamomile, valerian) | Insufficient evidence | Valerian is not recommended in pregnancy; chamomile in moderation is generally considered safe |
What to Avoid
- Melatonin supplements in pregnancy: Not enough safety data in humans exists to support use without explicit medical guidance. Unlike melatonin's general reputation as mild and harmless, its effects on fetal development are not well-studied.
- Valerian root: Insufficient evidence of safety in pregnancy; avoid.
- Prescription sleep medications: Most are not approved for use in pregnancy and some are contraindicated. Discuss with your OB if insomnia is severe enough to require consideration.
- Cannabis: Health Canada explicitly advises against cannabis use during pregnancy and breastfeeding due to potential harm to fetal development.
- Alcohol: Not safe in pregnancy regardless of sleep benefits.
Mattress Support for Pregnancy in Brantford
If you're pregnant and finding your current mattress isn't providing the hip and shoulder relief you need for side sleeping, come in and talk to us at 441 1/2 West Street. We can show you what medium-soft options might work for pregnancy side sleeping, and whether a topper might be a better fit than a replacement depending on your budget and timeline. Call (519) 770-0001 to ask what we have available.
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- Whitney double-sided mattress
- Somnia 3.0 posture support pillow
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Call 519-770-0001Frequently Asked Questions
Is insomnia in early pregnancy normal?
Yes. About 25% of people experience insomnia symptoms in the first trimester, primarily driven by surging progesterone, nausea, frequent urination, and anxiety. It's one of the earliest and most common complaints in pregnancy, though it often improves in the second trimester before returning in the third.
Can I take melatonin when pregnant?
This is a question for your OB or midwife specifically. Melatonin is produced naturally in the body and early research suggests the fetus is exposed to maternal melatonin, but the safety of supplemental doses in pregnancy hasn't been adequately studied. Most healthcare providers recommend avoiding supplemental melatonin in pregnancy unless specifically advised otherwise.
Why can't I sleep even when I'm exhausted during pregnancy?
Pregnancy hormones, particularly progesterone, disrupt sleep architecture even while causing significant daytime fatigue. This is the frustrating paradox many pregnant people experience. Slow-wave (deep) sleep decreases across all three trimesters, which means even adequate time in bed doesn't produce the same restorative sleep as it did before pregnancy.
Should I sleep on my left or right side during pregnancy?
Either side is acceptable. Left-side sleeping has a slight advantage in blood flow to the uterus due to the position of major vessels, but right-side sleeping is not harmful. The most important thing is avoiding prolonged back sleeping from mid-pregnancy onward (around 20 weeks). If you wake up on your back, simply roll to whichever side is more comfortable.
Does pregnancy insomnia mean my baby will have sleep problems?
No. Maternal insomnia during pregnancy is not predictive of infant sleep difficulties. Infant sleep behaviour is driven by developmental factors, not by maternal sleep patterns during pregnancy. Many women who experience severe pregnancy insomnia have babies who sleep well, and vice versa.
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