What Is the Circadian Rhythm?

Your circadian rhythm is your body’s internal 24-hour clock that regulates sleep, wakefulness, hormone release, and body temperature. It’s largely influenced by light and darkness and plays a key role in how rested and energized you feel each day.

During pregnancy, this finely tuned system undergoes significant changes—often leading to disrupted sleep and daytime fatigue.

How Pregnancy Affects Your Circadian Rhythm

Pregnancy doesn’t just change your body physically—it also alters your hormonal and biological rhythms.

1. Hormonal Shifts

Increased levels of progesterone and estrogen can directly impact your sleep-wake cycle. Progesterone, in particular, has a sedative effect, which can make you feel sleepier during the day but doesn’t always translate to better sleep at night.

2. Melatonin Changes

Melatonin, the hormone that signals your body it’s time to sleep, may be produced differently during pregnancy. Research suggests that melatonin levels can increase as pregnancy progresses, but the timing of release may shift, disrupting your natural rhythm.

3. Increased Nighttime Awakenings

Physical discomfort, frequent urination, and fetal movement can fragment sleep, making it harder for your circadian rhythm to stay consistent.

4. Temperature Regulation

Pregnancy raises your core body temperature, which can interfere with your body’s ability to initiate and maintain sleep, since cooler temperatures typically promote better rest.

Trimester-by-Trimester Sleep Changes

First Trimester

• Increased sleepiness due to rising progesterone

• More frequent naps, but also nighttime disruptions

Second Trimester

• Sleep may temporarily improve
• Circadian rhythm begins to stabilize slightly

Third Trimester

• More fragmented sleep due to physical discomfort

• Increased nighttime awakenings and earlier wake times

Why Circadian Rhythm Health Matters in Pregnancy

Maintaining a stable circadian rhythm during pregnancy is more important than many people realize. Disruptions have been linked to:

• Increased risk of mood changes, including anxiety and depression

• Greater fatigue and reduced daytime functioning

• Potential impacts on metabolic health

Emerging research also suggests that maternal circadian rhythms may influence fetal development, though this area is still being studied.

Signs Your Circadian Rhythm Is Disrupted

• Difficulty falling asleep at your usual time

• Waking frequently during the night

• Feeling tired during the day despite adequate time in bed

• Irregular sleep and wake times

Tips to Support a Healthy Circadian Rhythm During Pregnancy

Prioritize Light Exposure

Get natural sunlight in the morning to help regulate your internal clock. This is one of the most effective ways to stabilize your circadian rhythm.

Keep a Consistent Sleep Schedule

Go to bed and wake up at the same time every day—even on weekends—to reinforce your body’s rhythm.

Create a Wind-Down Routine

Develop a calming pre-sleep routine, such as reading or taking a warm bath, to signal your body it’s time to rest.

Limit Screen Time at Night

Blue light from phones and tablets can suppress melatonin production. Try to avoid screens at least an hour before bed.

Stay Active (When Safe)

Regular physical activity during the day can improve sleep quality and help regulate circadian timing. Always follow your healthcare provider’s recommendations.

Optimize Your Sleep Environment

Keep your bedroom cool, dark, and quiet to promote better sleep.

When to Seek Help

If sleep disturbances become severe or persistent, it may be worth discussing with your healthcare provider. Conditions like insomnia or sleep apnea can occur during pregnancy and may require targeted support.

The Bottom Line

Circadian rhythm changes are a normal part of pregnancy, driven by hormonal shifts and physical changes. While some disruption is expected, small daily habits—like consistent sleep timing and morning light exposure—can make a meaningful difference in how well you rest.

Call to Action:
Struggling with sleep during pregnancy? Start by setting a consistent bedtime tonight and getting 10–15 minutes of morning sunlight tomorrow—your body clock will thank you.

If you or someone you know struggles with sleep, please click the orange button below to take a free online sleep test and talk with one of our sleep health professionals.