Teresa Lillis, PhD, Rush University Medical Center.

Teresa Lillis, PhD

Wearables Show Disrupted Sleep 3 Months Postpartum, with Teresa Lillis, PhD

, Lillis discussed how wearable data revealed

 up to 13 weeks postpartum despite total sleep duration nearing pre-pregnancy levels.

At SLEEP 2025, Teresa Lillis, PhD, from Rush University Medical Center, presented new research findings that sleep duration gradually returned near baseline levels after the first week postpartum, but sleep consolidation stayed below pre-pregnancy levels throughout the first 13 postpartum weeks.

 to discuss the implications of these findings: What strategies should clinicians consider recommending to improve consolidated sleep for new mothers? Could consumer-grade wearables become a viable tool in postpartum clinical monitoring?

“I can't say enough good things about my experience working in wearable data here. You cannot get this level of detail with traditional lactography,” Lillis said.

In Lillis and colleagues’ study, 41 participants wore Fitbits that tracked sleep duration and longest stretch of sleep for 2 years: a full year before birth, during pregnancy, and a full postpartum year.

“That really allowed me to get the bird's eye view of what was going on with these moms,” Lillis said. “That helped me visualize just how…chunky sleep is after baby comes. Now, my personal experience as a mom told me that that's what happens to my sleep from the postpartum, but I wouldn't have been able to demonstrate that across all 40 women to have [those] same chunky patterns in the postpartum, had I not had access to wearable data. Moving forward, wearables are exactly the tools we need to help demystify or better understand what's going on with women's physiology, both during pregnancy and in the postpartum.”

Sleep duration reduced to near baseline levels (7.8 hours) during postpartum week 1 (4.4 hours), postpartum weeks 2 – 7 (6.7 hours), and postpartum weeks 8 – 13 (7.3 hours). The mean daily longest stretch of sleep fluctuated from 5.6 hours at pre-pregnancy, 2.2 hours during the first postpartum week, 3.2 hours during postpartum weeks 2 – 7, and 4.1 hours during postpartum weeks 8 – 13 (

Lillis said that the data was clinically meaningful and emphasized the need for postpartum women to receive better federal support. The study validates postpartum women’s sleep disturbances.

“I wrote my dissertation on postpartum sleep, and I was not prepared for how bad it was when I had my baby,” Lillis said. “So, I want this… data to prepare women and validate them.”

Lillis T, Hansen D, and Dongen H. Profound Postpartum Sleep Discontinuity In First-Time Mothers. Presented at SLEEP 2025, the 39th annual meeting of the Associated Professional Sleep Societies, from June 8th – 11th in Seattle.

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At SLEEP 2025, Lillis discussed how wearable data revealed disruptions in sleep consolidation up to 13 weeks postpartum despite total sleep duration nearing pre-pregnancy levels.

Wearables Show Disrupted Sleep 3 Months Postpartum, With Teresa Lillis, PhD

Postpartum Sleep Improves in Length, Not Quality, with Teresa Lillis, PhD

gradually returned near baseline levels after the first week postpartum, whereas sleep consolidation stayed below pre-pregnancy baseline levels throughout the first 13 postpartum weeks.

Teresa Lillis, PhD, from Rush University Medical Center, presented this research at 

SLEEP 2025, the 39th annual meeting of the Associated Professional Sleep Societies

spoke with Lillis at the meeting about sleep trends in new mothers.

“As a clinical psychologist, I've worked with pregnant and postpartum women for over 10 years…they are feeling exhausted,” Lillis said.

Despite this exhaustion, the literature shows new mothers have reasonable total sleep time. After the first postpartum week, many mothers will return to 6 to 7 hours of sleep. Studies have documented that new mothers only have modest sleep loss beyond the first postpartum week.

Yet, new mothers continue to be exhausted. Lillis pointed out that a normal sleep duration is not always correlated with well-rested restorative sleep.

“Across the first 3 months [postpartum]… they're really not all getting consolidated or uninterrupted sleep like they were before, certainly before pregnancy, and even most of pregnancy,” Lillis said.

Lillis and colleagues conducted a study using Fitbit data to track new mothers’ sleep duration and their longest stretch of sleep, a sleep consolidation metric that quantifies maternal sleep during the first 13 postpartum weeks. First-time mothers (n = 41) provided their sleep/wake wearable data from a full year before childbirth to the end of their first postpartum year.

During postpartum week 1, the mean daily sleep duration was 4.4 hours, compared with 7.8 hours pre-pregnancy. The mean daily longest stretch of sleep was 2.2 hours during this first postpartum week, compared with 5.6 hours at pre-pregnancy. Nearly a third of participants (31.7%) went ≥ 24 hours without sleep.

From pre-pregnancy to postpartum weeks 2 – 7, daily sleep duration increased to 6.7 hours. Daily longest stretch of sleep stayed low at postpartum weeks 2 – 7 (3.2 hours), compared with 5.5 hours pre-pregnancy.

During postpartum weeks 8 – 13, daily sleep duration was 7.3 hours, compared to 7.9 hours pre-pregnancy. The daily longest stretch of sleep was still reduced during postpartum weeks 8 – 13 (4.1 hours), compared to 5.6 pre-pregnancy. All the differences were significant (

“Our experimental sleep literature is telling us that when we chop up sleep with 8 little chunks and we have these awakenings at night, we don't allow someone to sleep in a continuous period,” Lillis said.

New mothers with sleep disturbances may experience postpartum depression. Lillis stresses the importance of getting a good night of non-disrupted sleep and recommends that someone else, whether that be a partner, family member, or friend, take care of the baby so the mother can get an uninterrupted stretch of sleep.

“That's a perfectly reasonable thing to recommend for the average mom, even if she's not clinically depressed, if she's just exhausted and she needs a stretch of sleep,” Lillis said. “That would be a recommendation that a healthcare provider can make.”

Lillis T, Hansen D, and Dongen H. Profound Postpartum Sleep Discontinuity In First-Time Mothers. Presented at SLEEP 2025, he 39th annual meeting of the Associated Professional Sleep Societies, from June 8th – 11th in Seattle.

By week 2 postpartum, sleep duration rebounds, but fragmented sleep persists through week 13, Teresa Lillis, PhD, presented at SLEEP 2025.

Teresa Lillis, PhD

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