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There is a distinct difference in your baby’s sleep pattern when you compare their sleep in the first three months and the sleep they start developing from month 4. From month 4, your baby’s sleep pattern matures, and will have more nights waking and more short naps. With this change, your baby will also start fighting sleep and becoming fussier and this is the sleep regression at month 4 that parents are all too familiar with.

Below is a table showing the sleep behaviors of your baby at 0 to 3 months and at month 4 when sleep regression begins.

From 0 to 3 monthsAt Month 4
14 to 17 hours of sleep per day12 to 16 hours of sleep per day
60% of sleep occurs at nightLess than 40% of sleep happens at night
Fewer wake-up periods at nightMore periods of wakefulness at night
Table showing the differences in sleep habits at months 0 to 3 and at month 4.

What is the 4-month sleep regression?

The 4-month sleep regression is a period of time (usually around the 4th-month mark) when your baby’s sleep patterns change and they start becoming less predictable, waking more often at night and taking shorter naps during the day. This can be an extremely frustrating time for parents who are just getting used to their baby’s sleep patterns, only to have them change again.

At month 4, babies start getting cycles of light sleep and deep sleep which are called REM (rapid eye movement) and non-REM sleep. In the first few months of life, babies spend most of their time in deep sleep which is why they sleep for long periods of time and don’t wake up often. As they start to get more cycles of light and deep sleep, they become more aware of their surroundings and start to wake up more at night.

During the day, their naps become shorter because they are getting more light sleep and less deep sleep. This can be frustrating for parents because it seems like their baby is sleeping less overall compared to the earlier months (0 to 3 months).

From the 4th month, your baby begins the sleep consolidation process, which means your baby’s sleep periods increases and become more like an adult’s sleep pattern.

Origin of sleep regression

Sleep regression has been noted in infants for many years. In 1974, Robert Horwich, an animal researcher at the Chicago Zoological Society, noticed that several infant members of 12 different primate species tended to change their nursing habits at roughly the same times. He called these phases of heightened nursing “regressive periods”, defining them as a time during which infants revert to a level of neediness and clinginess that they had previously outgrown.

Sleep regression can occur at different ages but is most common around 4 months, 8-10 months, and 18 months. Many babies will go through more than one sleep regression during their first year or two.

4 month sleep regression signs and symptoms

There are a few signs and symptoms that you can look out for to see if your baby is going through the 4-month sleep regression:

  1. Waking up at night: Your baby starts waking up more at night compared to before
  2. Shorter naps: Your baby takes shorter naps during the day or starts fighting naps altogether
  3. Fussiness: Your baby becomes fussy and cranky, especially in the evenings
  4. Difficulty falling asleep: Your baby has a hard time settling down to sleep at bedtime
  5. Fewer sleeping hours: Reduced sleep time overall from 14 to 17 hours a day to 12 to 16 hours a day

Why do babies have a 4-month sleep regression?

During the 4th month, your baby experiences a lot of mental and physical development that will impact their sleep cycles. Some of the causes of the 4-month sleep regression during this period include;

  • The development of REM sleep: As your baby starts to get more cycles of light and deep sleep (REM and non-REM), they become more aware of their surroundings and start to wake up more at night.
  • The decrease in daytime sleep: As your baby’s naps become shorter, they are getting less deep sleep during the day. This can make them more tired and cranky at night.
  • The development of new skills: Around the 4-month mark, babies start to develop new skills such as rolling over, sitting up, and crawling. These new skills can be exciting for your baby but can also lead to less sleep at night as they practice them.
  • They may be teething, which can cause discomfort and make it difficult to sleep.
  • They may be experiencing a developmental leap, which can cause them to be more alert and less sleepy.

How long does the 4-month sleep regression last?

The 4-month sleep regression usually lasts for 2-6 weeks. However, it can be shorter or longer for some babies. If your baby is taking shorter naps during the day and waking up more at night, try to be patient and give them time to adjust to the new sleep pattern.

When does it start??

The 4-month sleep regression usually starts around the 4-month mark but can start as early as 3 months or as late as 6 months. Unlike newborns from 0 to 3 months that have 4 cycles of sleep, 4-month-olds have 2 sleep cycles. Below are the cycles;

  • The first cycle is light sleep followed by deep sleep (REM sleep).
  • The second cycle is light sleep followed by awake.

When can I expect the 4-month sleep regression to end?

By the 5 or 6th month, you can expect your baby to be able to sleep on their own and have matured to master the different sleep cycles. The dreaded 4-month sleep regression usually does not exceed 6 weeks from the day your baby clocks 4 months.

Does the 4-month sleep regression affect naps?

You’ll have to grapple with shorter naps during this period of 4-month sleep regression. Expect your baby to wake up after 30 to 45 minutes of sleep and they may not be able to fall back asleep without your help. I often found my daughter needed to be rocked or nursed back to sleep.

Effective tips to overcome the 4-month-old sleep regression

If your baby is going through the 4-month sleep regression, here are some tips that may help:

1. Keep a consistent bedtime routine: A bedtime routine can help signal to your baby that it’s time to sleep. Try to keep the routine short and sweet, and include activities that your baby enjoys such as reading a book or singing a song.

2. Put your baby down when they’re sleepy: Don’t wait until your baby is asleep to put them down in their crib or bassinet. You want to put them down when they’re sleepy but still awake so they can learn to fall asleep on their own.

3. Avoid stimulating activities before bed: Try to avoid any stimulating activities such as watching television or playing with toys before bedtime. Instead, opt for calming activities such as reading or cuddling.

4. Create a relaxing environment: Make sure the environment in your baby’s bedroom is peaceful and calming. This may include keeping the lights low, using a blackout curtain, using a white noise machine, and avoiding any loud noises.

5. Don’t feed your baby to sleep: If you’re still feeding your baby to sleep, now is the time to break that habit. You want your baby to learn to self-soothe and fall asleep on their own. Read about baby feeding at night here.

6. Keep nights and days separate: It’s important to keep your baby’s sleep schedule separate from their awake time. This means avoiding any naps during the evening hours so they’re more tired at bedtime.

7. Be patient: The 4-month sleep regression can be frustrating for both you and your baby. But it’s important to be patient and understand that this is just a phase. It won’t last forever, and eventually your baby will sleep through the night again.

Sleep and other developmental changes with babies at 3 – 4 months:

To regulate their sleep cycle, babies start to produce their own melatonin, the hormone that makes them feel sleepy.

During the day, their naps become shorter because they are getting more light sleep and less deep sleep.

At night, they may wake up more often because they are going through light and deep sleep cycles.

They may start to develop new skills such as rolling over, sitting up, and crawling.

The circadian rhythm, an internal “body clock” that regulates when we feel awake and sleepy, starts to develop.

So what can I expect in the 4-month sleep regression:

A lot of sleep disruptions! When your baby falls asleep in your arms and you have to take them to the crib, you expect them to embrace the crib and sleep for long but nope! As they go through deep and light sleep, they may briefly notice the change in their environment and they freak out leading them to become fully awake. And you’ll have to start over again. You may need to try out different ways to get them to sleep – Sleep Sense’s methods, Swaddle, Ferber’s methods, or 5Ss to shush them to sleep again.

What other things are common during 4-month sleep regression;

  • During the day, your baby may take shorter naps and be crankier than usual.
  • At night, your baby may wake up more often and have a harder time falling asleep.
  • Your baby may also start to practice new skills such as rolling over, sitting up, and crawling.

How to cope with 4-month sleep regression:

  • Understand what’s causing the regression: The 4-month sleep regression is caused by your baby’s circadian rhythm (internal “body clock”) starting to develop but can also be caused by other factors such as sleep association. If sleep association is the problem, then you’ll need to help your baby learn how to fall asleep without relying on you.
  • Follow safe sleep guidelines: Make sure you are following all the safe sleep guidelines such as putting your baby to sleep on their back and using a firm mattress.
  • Daytime playtime can go a long way: During the day, make sure your baby gets plenty of tummy time to help them build up their muscles. You can also try to engage in some playful activities with your baby to help tire them out.
  • Get your baby a safe and comfy sleep environment: A dark and quiet room can help your baby sleep better at night. You might want to try using a white noise machine to help soothe your baby and help them fall asleep.
  • Create a bedtime routine: Having a consistent bedtime routine can help signal to your baby that it’s time to sleep. This may include bathing, reading a book, and singing a lullaby.

When Should I talk to my pediatrician about my baby’s sleep problems at 4-months?

AAP advises parents to seek medical help for their baby if:

  • Your baby is not gaining weight steadily
  • Your baby’s food intake is reduced
  • Your baby’s diaper change cycles are reduced – including urination periods

4 month sleep regression myth

There is a myth that 4-month sleep regression is not the real thing and that somehow you can get your baby trained to sleep and avoid the 4-month sleep regression altogether. Having worked with several kids and having study research on the topic, I can confidently say that the 4-month sleep regression is real. It’s a phase that all babies go through and there’s no avoiding it. So don’t believe the myth and be prepared for some sleep disruptions around the 4-month mark!

It doesn’t just happen to humans. In the 1974 study, they realized that infants of 12 different species went through this sleep regression phase.

It doesn’t just happen to humans. In the 1974 study, they realized that infants of 12 different species went through this sleep regression phase. Whether you are reading from Kellymom blog or the NY Times, there is no alternative truth to the fact that sleep regression exists.

4 month sleep regression FAQs

Q: Do all babies have sleep regression at 4-months old?

A: While sleep regression is common at 4-months old, not all babies will experience it.

Q: Will the 4-month sleep regression happen every 4 months?

A: No, the 4-month sleep regression is not a recurring event. It typically only happens once during infancy.

Q: What if my baby’s sleep regression lasts longer than 6 weeks?

A: If your baby’s sleep regression lasts longer than 6 weeks, it’s best to consult with your pediatrician. They can rule out any underlying medical conditions and offer additional tips and advice.

Q: How can I best prepare for 4-month sleep regression?

A: There are a few things you can do to prepare for 4-month sleep regression:

  • 1. Establish a bedtime routine
  • 2. Put your baby to bed drowsy but awake
  • 3. Avoid any stimulating activities before bedtime
  • 4. Create a relaxing environment in your baby’s bedroom
  • 5. Don’t feed your baby to sleep
  • 6. Keep nights and days separate
  • 7. Be patient!
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