Why Some Babies Grow Faster in the Night Than During the Day

Your baby may grow overnight, which may be a bit hard to believe. But it happens, as they can outgrow clothes, appear longer, or feel heavy in the morning. This is not your mind making things; babies can grow faster at night than during the day. Nighttime growth is crucial for your baby’s overall development. You can help them in such times by maintaining their sleep routine to support healthy growth.

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You may closely observe every little detail about your baby. Some days, you may notice that their growth happens suddenly, almost overnight. But the science supports this, as babies do not grow at a steady pace throughout the day. Most of their physical growth happens at night while they sleep.
Understanding the importance of a sleep routine in your baby’s development can help you give them the best start to their life.

Why Does Growth Often Happen More at Night?

Sleep in babies is critical to their growth. Your baby uses energy to move, feed, and cry during the day. However, their bodies shift focus at night to repair and grow.

The body releases important hormones that support physical development during deep sleep. So, nighttime is an ideal period for growth.

How Does Sleep Support Baby Growth?

Sleep is an active period for your baby’s body and brain.

The role of growth hormone

The human growth hormone (HGH) is released during deep sleep. Studies show that nearly 70–80% of growth hormone release in infants and children occurs during nighttime sleep in the early part of the night.

This hormone helps in several ways.

  • Increase the length of bones
  • Build muscle tissue
  • Repair cells
  • Support healthy weight gain
The hormone may not be released in the required quantity without adequate sleep.

Energy conservation during sleep

Your baby’s body is not spending energy on movement or alertness at night. So, all the energy goes toward growth and repair, making nighttime better for physical development.

Why Is Deep Sleep Important for Physical Development?

Babies experience different stages of sleep. Out of which the deep sleep stage, also known as slow-wave sleep, is the most important growth stage.

What happens during deep sleep?

  • Growth hormone levels peak
  • Bones absorb calcium better
  • Muscles relax and rebuild
  • Tissues repair themselves
Newborns can spend 40–50% of their sleep time in deep sleep, which is why growth is rapid in the first year of life.

Do Babies Really Grow in Short Bursts?

Baby’s growth happens in spurts rather than gradually.

Understanding growth spurts

Growth spurts commonly occur around the following times:

  • 2–3 weeks
  • 6 weeks
  • 3 months
  • 6 months
  • 9 months
You may notice the following behaviour in your baby around this time.

  • Increased night waking
  • More frequent feeding
  • Little fussiness
  • Sudden changes in length or weight

Why Doesn’t the Same Growth Happen During the Day?

Daytime hours are more for learning and movement, and not physical growth.
Your baby’s body priorities are different during the day.
  • Brain stimulation
  • Motor skill development
  • Social interaction
  • Sensory learning

Does Feeding at Night Affect Growth?

Nighttime feeding supports growth in babies.

Nutritional support during sleep

Breast milk or formula provides calories, protein, and fats needed for growth. Night feeds give your baby enough energy reserves for tissue repair and development.

Breast milk also contains melatonin, which helps regulate sleep cycles and indirectly supports growth.

What Role Does Routine Play in Nighttime Growth?

Your baby’s body follows a healthy internal clock.

Importance of a predictable schedule

A regular bedtime routine helps your baby enter deep sleep stages more easily. You can make your own routine.

  • Gentle bathing
  • Quiet feeding
  • Dim lighting
  • Calming song or talks

Emotional Security and Its Impact on Growth

Your baby’s emotional state also directly affects physical development.

The mind–body connection

Stress hormone levels remain low when your baby feels safe. High stress hormones, such as cortisol, can interfere with growth hormone activity.

Your presence, touch, and response at night help your baby feel secure so that they can focus on growth rather than stress.

Your partner’s support is also important because your baby can benefit from a calm environment after you share responsibilities. You experience less exhaustion and anxiety, which allows you to be emotionally present for your baby.

When Should You Be Concerned About Growth Patterns?

Nighttime growth is normal, but some signs may need urgent medical attention.

Warning signs to watch for:

  • Your baby is not gaining weight as expected
  • Growth measurements consistently fall below standard growth charts
  • Your baby sleeps very poorly for long periods
  • Feeding difficulties persist

What Can You Do to Support Healthy Nighttime Growth?

You can take easy steps to support growth.

What to do next: A helpful checklist

  • Allow your baby to get enough total sleep in 24 hours
  • Maintain a calming bedtime routine
  • Feed your baby well, even at night
  • Keep the room quiet and comfortable
  • Respond to night waking for feeds
  • Attend regular check-ups to track the growth of your baby
Babies can grow overnight, as the conditions support their growth due to the release of hormones. Their energy goes towards cell repair and growth when they are in deep sleep. Nighttime supports physical development, while daytime is for activities. You can help your baby grow healthily by building a sleep routine.

Whether you’re pregnant, a new mom, or navigating postpartum, you don’t have to do it alone. Join our support group to connect, share, and support one another.

FAQs on Why Some Babies Grow Faster at Night Than During the Day?


  1. Can poor sleep slow down a baby’s growth?
    Poor sleeping patterns in the long run may affect the release of growth hormone. However, short-term disruptions in sleep are not harmful. You can follow a consistent sleep routine to improve the quality over time.
  2. Do premature babies also grow more at night?
    Premature babies rely on nighttime sleep the most for growth, though they may feed frequently and require close monitoring.
  3. Should you wake a sleeping baby at night to feed for growth?
    Waking your baby up for feeds may be necessary in the early months or if advised by a doctor. But most babies can sleep longer after a steady growth without any problems.
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