Does Breastfeeding Make You Tired? What Sleep Studies Actually Show

Written by the Nuvirox Research Team

Short answer: breastfeeding doesn't reliably cause more fatigue than formula feeding, according to the sleep research directly comparing the two — and in a couple of well-designed studies, breastfeeding mothers actually got slightly more nighttime sleep. That's a genuinely counterintuitive finding worth taking seriously, since the opposite assumption is so widespread.

Don't breastfeeding mothers get less sleep than formula-feeding mothers?

Not according to the direct comparisons — several studies find the opposite, or no meaningful difference. A study published in the Journal of Clinical Sleep Medicine examined nighttime breastfeeding behavior in first-time mothers at one month postpartum and found that nighttime breastfeeding was associated with more, not less, nocturnal sleep. The authors noted there's no firm evidence that supplementing with formula increases infant or maternal sleep time or reduces sleep fragmentation, despite that being a commonly held belief among new parents.

A separate prospective observational study tracking sleep and fatigue by feeding method across late pregnancy through early and late postpartum found that fatigue actually decreased over time in the bottle-feeding group, while it remained essentially unchanged from late pregnancy through postpartum in the breastfeeding group — but the two groups ended up with similar overall fatigue levels by late postpartum, and there were no differences in sleep quality or insomnia symptoms between them at any point measured. In other words, the trajectories differed slightly, but breastfeeding wasn't shown to leave mothers more exhausted overall.

Why might breastfeeding not be as exhausting as assumed?

Prolactin, the hormone responsible for milk production, appears to have real sleep-promoting effects. Prolactin is released during breastfeeding and nursing-related nipple stimulation, and research has linked it to increased slow-wave (deep) sleep. One laboratory study found lactating women spent more time in deep sleep stages than formula-feeding women, an effect the researchers linked to higher circulating prolactin, though they were careful to note this hasn't been definitively established as the specific causal mechanism. Oxytocin, also released during breastfeeding, is separately associated with relaxation and stress reduction, which plausibly supports falling back asleep more easily after a night feed compared with, for example, getting up to prepare and warm a bottle.

None of this means breastfeeding is effortless or that every mother experiences it this way — individual experiences vary considerably based on latch difficulties, supply concerns, pain, and the baby's own sleep patterns, none of which these average-effect studies fully capture. But it does mean the blanket claim that breastfeeding is inherently more exhausting than formula feeding isn't well supported by the sleep research that has directly measured the comparison.

So what is actually driving the exhaustion so many nursing mothers feel?

Most likely the same factors affecting postpartum parents regardless of feeding method: the newborn period itself, and depressive symptoms specifically. The postpartum period, independent of feeding choice, brings substantially disrupted total sleep time due to nighttime infant care, hormonal shifts, physical recovery from birth, and reduced support from others — all factors that affect breastfeeding and formula-feeding parents alike. One study specifically found that the presence of postpartum depressive symptoms was associated with earlier switching from breastfeeding to bottle feeding, suggesting depression and fatigue may sometimes be part of why breastfeeding feels unsustainable, rather than breastfeeding itself being the root cause of the exhaustion.

What breastfeeding fatigue won't explain, and an important safety note

If you're taking a sleep-support supplement or herbal product while breastfeeding, it's important to know that ingredients like St. John's Wort and 5-HTP can pass into breast milk, and their safety profile for nursing infants isn't well established the way it is for many standard medications. This is a genuine reason to check with your pediatrician or a lactation-aware physician before adding any new supplement while breastfeeding, rather than assuming anything marketed for adult sleep or energy is automatically fine during lactation. Severe, unrelenting fatigue that doesn't track with your baby's sleep pattern, or that comes with low mood, anxiety, or thoughts of harming yourself or the baby, warrants prompt evaluation for postpartum depression rather than being attributed to breastfeeding alone.

What actually helps

Sleeping when the baby sleeps remains genuinely useful advice, even though it's a cliché, simply because total sleep time is the biggest lever available in the newborn period regardless of feeding method. Accepting practical help with other tasks so sleep opportunities aren't lost to housework or other demands, and screening for postpartum depression if fatigue feels disproportionate or comes with low mood, are both more targeted responses than assuming breastfeeding itself is the fixable variable.

From Nuvirox

Why we formulated NAD+ Restore

• 500 mg Nicotinamide Riboside Chloride (NR) per serving — one of the two most-researched NAD+ precursors, within the dose range used in published human trials
• 150 mg trans-resveratrol + 50 mg quercetin — polyphenols studied alongside NAD+ pathways for cellular health support
• 10 mg galactomannans from fenugreek to support absorption
• Backed by a 60-day money-back guarantee — long enough to actually evaluate it the way the research says you should

Because of what's discussed above, we'd encourage talking with your doctor or pharmacist before adding any new supplement, including this one, especially if you take prescription medication.

Learn more about NAD+ Restore →

Frequently asked questions

Will switching to formula help me sleep more?

The direct research comparing feeding methods doesn't show a clear sleep advantage to formula feeding, and one study found nighttime breastfeeding associated with more nocturnal sleep, so switching isn't well supported as a fatigue fix on its own.

Is it safe to take a sleep supplement while breastfeeding?

Not automatically. Ingredients like St. John's Wort and 5-HTP can transfer into breast milk, and safety data in nursing infants is limited, so it's important to check with your pediatrician or a lactation-knowledgeable provider before using any new supplement while nursing.

Why do I feel exhausted at night even though my baby is a good sleeper?

This can point toward something other than infant sleep patterns — postpartum depression, anemia from birth-related blood loss, or a thyroid issue are all common and treatable contributors worth checking with your doctor.

Does pumping instead of direct nursing change the fatigue picture?

The available research mostly compares breastfeeding broadly to formula feeding rather than isolating pumping specifically, so there isn't strong direct evidence either way, though pumping does add its own time demands that direct nursing doesn't.

The bottom line: the sleep research directly comparing breastfeeding to formula feeding doesn't support the common assumption that nursing is inherently more exhausting — in some studies, the opposite showed up. The real drivers of new-parent fatigue are more likely the newborn period itself and, in some cases, postpartum depression, both of which deserve attention on their own terms rather than being blamed on the feeding method.

References

1. Doan T, Gay CL, Kennedy HP, Newman J, Lee KA. Nighttime Breastfeeding Behavior Is Associated with More Nocturnal Sleep among First-Time Mothers at One Month Postpartum. J Clin Sleep Med. 2014;10(3):313-319. PMC3927438.
2. Mariman A, Hanoulle I, Pevernagie D, et al. Longitudinal assessment of sleep and fatigue according to baby feeding method in postpartum women: a prospective observational study. BMC Pregnancy Childbirth. 2024;24:article. PMC11321152.
3. Noel GL, Suh HK, Frantz AG. Prolactin release during nursing and breast stimulation in postpartum and nonpostpartum subjects. J Clin Endocrinol Metab. 1974;38(3):413-423.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.