You may have heard of the 4-month sleep regression and dreaded the thought of your baby going through it. The truth is, this is a maturation of development and sleep.3 It can feel challenging, but it’s a good sign that your baby’s body will soon be ready to sleep in more regular patterns.
The 4 Month Sleep Regression
Most babies go through the 4-month sleep regression between 3 and 5 months old. You will often notice signs of the changes around 3-3.5 months old.3,7 By 5 months, you can work on a more solid schedule and balance out sleep if this is your goal. Here’s what you need to know about the 4-month sleep regression:
What’s Happening During This Sleep Shift?
You may be wondering how newborn and matured sleep differ. So, let’s explore how your baby’s sleep will change during this time:
Newborn Sleep
Newborn sleep is simple, with two distinct stages of sleep: REM sleep (also called “active” sleep) and non-REM sleep (also called “quiet” sleep). REM (active) sleep is when you may notice them twitching, breathing irregularly, and smiling and see their eyes moving beneath their eyelids.1,4 Non-REM (quiet) sleep is when your baby is breathing deeply and lying very still.4
4 Month Sleep Shift
During this sleep regression, many changes begin to occur in the body:1,4
- Your baby is producing more melatonin! Melatonin is our sleep hormone that tells the body when it’s sleep time. Before this change, your baby’s physical needs determined their wake/sleep cycle more.
- Non-REM sleep is further dividing. There are now four stages of sleep, and some periods of “deep” sleep are lighter than others.
- Partial awakenings occur during the sleep cycles. These awakenings generally happen once a sleep cycle and serve the purpose of protecting our baby (we have them too!). Your baby comes out of sleep to assess their surroundings and ensure they’re safe and their needs are met.
These awakenings are a primary factor in sleep disruptions. Before this developmental milestone, your baby usually woke for a physical need of feeding, a diaper change, or comfort.5 Now, they’re experiencing these awakenings even if they don’t need anything. This is where babies begin to form associations for sleep. Cues that are present when your baby falls asleep become a cue for sleep in the brain. When they come into a partial awakening and don’t have a physical need, their body will need the cue to go back to sleep. Once your baby goes through this maturation, you may notice that they have more night wakings and shorter naps, and it can be harder to put them to sleep.3,6 This is what I refer to as a negative association. It is NOT “bad,” but it interrupts sleep.
Matured Sleep
Following the sleep shift, your baby’s sleep pattern will be similar to yours.7,8 Sleep cycles will lengthen as they get older, and you’ll see a natural shift to more night sleep and less daytime sleep through nap transitions and longer awake times.6,8 However, partial awakenings are still part of the sleep cycle, and cues for sleep can get stronger. This is often when families notice their baby frequently wakes at night and takes short naps even though the sleep regression has passed.3,6,9
Working on the cues that your baby uses at the beginning of the night to fall asleep can greatly improve night wakings.3 Your baby will have new strategies for going back to sleep during the awakenings if they don’t have a physical need, such as a feed.
How To Get Through the 4 Month Sleep Regression
Here are some tips for getting your baby through this time:
- Use appropriate awake times between sleep periods. For example, an overtired baby and a baby who isn’t tired enough can wake more frequently and/or take short naps.
- Follow wake windows to allow for an early bedtime. For example, a bedtime between 6 and 8 p.m. is normal around the five to six months following the sleep shift.
- Have the last nap of the day end by 5:30 p.m. This sets up a nice bedtime for your little one.
- Set up the room environment properly. Set it up to help sleep cycles flow and sleep hormones be produced.
- Focus on consistent routines. Routines are your baby’s clock, and help signal the brain to produce sleep hormones and prepare for sleep.2
- Be patient! The shift can take time, and I truly believe that months three to four are the hardest in terms of sleep. Your baby isn’t ready for sleep strategies until four months old, yet the maturation of those sleep cycles is kicking your butts.
We hope this information has helped prepare you for the 4-month sleep regression. Establishing good sleep habits for your baby can be beneficial. And don’t worry — you and baby will get through this difficult period!
