Does Breastfeeding Make You Tired? Why It Happens and When to Worry

If you’ve ever felt your eyelids drop the moment your baby latches on, you’re not imagining it. Many parents feel a wave of sleepiness during feeds, and the first months of breastfeeding can bring a tiredness unlike anything before. So yes, breastfeeding can make you tired, but it’s rarely the whole story.

This guide explains the hormones behind that drowsy feeling, why broken sleep is the bigger factor, practical ways to get more rest and the medical causes of exhaustion that are worth checking with a doctor.

The hormones behind feeling sleepy

Two hormones drive breastfeeding:

• Prolactin tells your body to make milk. Its levels rise with feeding and are naturally higher at night.
• Oxytocin triggers the let-down reflex that releases milk.

A 2022 study in the journal Birth summarizes research suggesting that both hormones also affect sleep. Oxytocin counters the stress hormone cortisol and helps you relax, and prolactin may help you fall asleep faster and spend more time in deep sleep. Much of this evidence comes from animal studies, so it’s not fully proven in people, but it fits with what many parents feel: calm and drowsy during and after a feed.

That relaxed feeling can actually be helpful at night, because it may make it easier to fall back asleep after a feed.

The bigger reason: broken sleep

The main reason new parents are exhausted is that their sleep is interrupted again and again. Newborns need to feed often, around the clock. Our guide on how often to breastfeed explains why 8 to 12 feeds in 24 hours is normal early on.

In the same 2022 Birth study, researchers followed mothers through the first two years after birth. Whether a mother was breastfeeding, and how much breast milk her baby got, was not significantly linked to her total sleep time. What mattered most was the number of night feeds: each extra feed meant several minutes less sleep and less efficient sleep, however the baby was fed. The authors concluded that getting up to feed, rather than breastfeeding itself, disrupts sleep.

Other things add up too:

• Recovery from birth, especially after a cesarean or a difficult delivery
• Growth spurts and cluster feeding, which can mean long evenings at the breast
• Not eating or drinking enough while caring for a baby
• Worry and mental load, which can make it hard to sleep even when the baby does

Fueling your body

Making milk uses energy. The CDC says well-nourished breastfeeding women need about 330 to 400 extra calories a day compared with before pregnancy, and that needs for several nutrients, including vitamin B12, folate and vitamin D, rise while breastfeeding. The National Academies’ 2023 energy report arrives at a similar figure by a different route: about 540 calories a day to make milk during exclusive breastfeeding in the first 6 months, minus 140 from body stores, or roughly 400 extra a day, and 380 extra at 7 to 12 months. Your own number depends on your size, activity and how much of your baby’s food is breast milk. Skipping meals can make tiredness worse.

• Keep easy breastfeeding snacks and a drink where you usually feed.
• Eat regular meals with protein, whole grains, fruit and vegetables.
• Drink to thirst.
• Use our breastfeeding calorie calculator for a rough daily target, especially if you’re trying to lose weight.

Ways to get more rest

You can’t skip night feeds with a young baby, but you can make them less draining:

• Share the load. A partner or helper can handle diaper changes, burping, settling and household tasks. If you pump, another person can give an occasional bottle.
• Keep night feeds calm. Low light, minimal talking and no screens help both of you get back to sleep faster.
• Sleep when you can. Rest during the day when your baby naps, even briefly, and say yes to offers of help.
• Try feeding lying down. Many parents find side-lying breastfeeding more restful, as long as you follow safe sleep rules.
• Lower your expectations elsewhere. Housework can wait.

A note on safe sleep

Because breastfeeding can make you drowsy, plan ahead. The AAP warns against falling asleep with your baby on a couch, soft armchair or cushion, where the risk of sleep-related infant death is up to 67 times higher. If you bring your baby into bed to feed or comfort them, the AAP advises putting them back in their own sleep space before you go to sleep. Babies should sleep on their backs, in your room but not in your bed, for at least the first 6 months.

When tiredness may be something more

Some tiredness is expected. But exhaustion that doesn’t improve with rest, or that comes with other symptoms, can have a medical cause.

Anemia (low iron)

Blood loss during birth and low iron during pregnancy can leave you with iron deficiency anemia. The NHS lists tiredness, shortness of breath, a fast or pounding heartbeat, pale skin and headaches as common symptoms. A simple blood test can check for it. Don’t start iron tablets without talking to your doctor, and keep them well out of reach of children, as iron overdose is dangerous for young kids.

Thyroid problems

Postpartum thyroiditis is inflammation of the thyroid after pregnancy. Cleveland Clinic estimates it affects 5% to 10% of women in the year after giving birth. It often starts with an overactive phase (1 to 6 months after birth), then an underactive phase (usually 4 to 8 months after birth) that can cause fatigue, weight gain, low mood, dry skin, constipation, feeling cold, and, according to Cleveland Clinic, not enough milk coming in. A blood test can diagnose it. Tell your provider you’re breastfeeding so they can choose treatments that are safe for you and your baby.

Postpartum depression

The NIMH lists fatigue or a big drop in energy, trouble sleeping even when the baby sleeps, low mood, loss of interest, guilt and difficulty bonding with your baby as signs of perinatal depression. The “baby blues” are common in the first 2 weeks, but mood changes that are severe or last longer than 2 weeks may be postpartum depression, which usually needs treatment to improve. Tell your provider you’re breastfeeding so they can suggest options that fit.

You can call or text the National Maternal Mental Health Hotline at 1-833-TLC-MAMA (1-833-852-6262), free and available 24/7. If you have thoughts of harming yourself, call or text 988, or call 911 in an emergency.

Other causes

Being sick, infections such as mastitis, poor sleep from other causes, and some medicines can all add to fatigue. If you’re unwell, you can usually keep breastfeeding; ask your doctor which medicines are safe.

When to see a doctor

Make an appointment if:

• You’re still exhausted even when you get a chance to sleep
• You feel dizzy or short of breath, or your heart races
• You have symptoms of thyroid problems, such as feeling unusually cold or hot, weight changes, a racing heart or very dry skin
• Your milk supply suddenly drops along with tiredness
• You’ve had heavy bleeding since the birth
• You’ve felt low, anxious or hopeless for more than 2 weeks

Get urgent help if you have thoughts of harming yourself or your baby, confusion or hallucinations. For more on looking after yourself while you nurse, visit our nutrition and health hub.