Study quantifies the sleep loss and disruption experienced by new mothers

Results show that the average daily sleep duration of new mothers was 4.4 hours during the first week after giving birth compared with a pre-pregnancy sleep duration of 7.8 hours. Their longest stretch of uninterrupted sleep also fell from 5.6 hours at pre-pregnancy to 2.2 hours in the first week after delivery. Nearly one-third of participants (31.7%) went more than 24 hours without sleep in the first week with a newborn.

The daily sleep duration of new moms increased to 6.7 hours across postpartum weeks 2 through 7 and 7.3 hours across weeks 8 through 13. However, their longest stretch of uninterrupted sleep remained significantly lower than pre-pregnancy levels at 3.2 hours in weeks 2 through 7 and 4.1 hours in weeks 8 through 13. This novel finding reveals that sleep discontinuity remains a problem for new mothers even as their total nightly sleep duration gradually returns to pre-pregnancy levels.

"The significant loss of uninterrupted sleep in the postpartum period was the most dramatic finding," said lead author Teresa Lillis, who has a doctorate in clinical psychology and is an adjunct professor in the department of psychiatry and behavioral sciences at Rush University Medical Center in Chicago. "While mothers generally returned to their pre-pregnancy total nightly sleep duration after the first postpartum week, the structure of their sleep remained profoundly altered. These results fundamentally transform our understanding of postpartum sleep; it's not the lack of sleep, but rather, the lack of uninterrupted sleep that is the largest challenge for new mothers."

The study involved 41 first-time mothers between the ages of 26 and 43 years. They provided their wearable sleep data from their personal Fitbit devices for a full year before childbirth through the end of the first year after giving birth.

Lillis noted that these findings explain why new mothers continue to feel exhausted even when they get the recommended 7 or more hours of sleep per night. The study results also identify sleep discontinuity as a potential risk factor and intervention target for postpartum depression and other postpartum-related health issues.

"Our results validate the lived experience of new mothers' exhaustion and provide a new target for sleep-related interventions," she said. "Rather than simply encouraging mothers to 'nap when the baby naps', our findings show that mothers would most benefit from strategies that protect opportunities for uninterrupted sleep."

This study was supported by trackthatsleep LLC, for which Lillis serves as CEO. The study was conducted at Washington State University's Sleep and Performance Research Center with co-investigators Devon Hansen and Hans Van Dongen.

The research abstract was published recently in an online supplement of the journal Sleep and will be presented Monday, June 9, during SLEEP 2025 in Seattle. SLEEP is the annual meeting of the Associated Professional Sleep Societies, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society.