Postpartum sleep
Breastfeeding mothers slept 40 minutes more per night
At a glance
| Study type | Cross-sectional study |
|---|---|
| Year | 2007 |
| Journal | Journal of Perinatal & Neonatal Nursing (21(3):200-206) |
| Sample | n = 133 |
| Effect size | +40 min sleep for mothers, +38-44 min for fathers |
| Population | Postpartum |
Background
In a secondary analysis of an RCT of 133 couples at 3 months postpartum, exclusively breastfeeding mothers slept 40 minutes longer per night than mothers who supplemented with formula. Their partners also slept more.
Wasn't the conventional wisdom that formula gives parents more sleep?
Yes — and this paper is the canonical counterexample. Doan and colleagues at UCSF analyzed sleep diaries and actigraphy in 133 couples and found exclusive breastfeeding associated with longer maternal sleep, not shorter. The leading explanation is that breastfeeding mothers don't fully wake to prepare bottles and resettle infants, and prolactin drives sleepiness that helps re-onset.
How big was the effect?
Exclusive-breastfeeding mothers slept 7.2 ± 1.3 hours; formula-supplementing mothers slept 6.4 ± 1.3 hours (p = .008). Evening breastfeeding mothers got an extra 45 minutes (p = .004); night breastfeeding, 47 minutes (p = .010). Fathers in breastfeeding households slept 38–44 minutes more than fathers in supplementing households.
What if breastfeeding isn't an option for me?
The point of the paper isn't 'breastfeed or you'll lose sleep' — it's that the assumption that switching to formula buys more sleep is unsupported by the cleanest controlled data we have. If you're formula-feeding for medical, supply, or personal reasons, focus the sleep optimization elsewhere: bedroom light (Mason 2022), partner-shared night feedings, and protected daytime nap windows.
Why did mothers with sole feeding responsibility sleep more, not less?
The trial found mothers with sole feeding responsibility slept 7.1 hours vs 6.2 hours in shared-responsibility households. The likely explanation is the cost of waking up coordinating with a partner — alarm clocks, talking, switching off — adds more cognitive load than handling the wake yourself in a low-light, low-stimulation way.
How does Solas apply this?
Solas's postpartum recommendations don't push breastfeeding — they apply the underlying mechanism (minimize cognitive activation during night wakes, keep light low) to whichever feeding situation you're in.
Source
Doan T, Gardiner A, Gay CL, Lee KA (2007). Breast-feeding Increases Sleep Duration of New Parents Journal of Perinatal & Neonatal Nursing (21(3):200-206).
Solas does not own or distribute the underlying paper. Follow the link to the publisher for the full text. See our methodology.