A four-month-old needs 12 to 16 hours of total sleep per 24-hour period, split between nighttime sleep and daytime naps. Most babies this age get around 10 to 12 hours at night (with wakeups for feeding) and about 4 hours of daytime sleep spread across multiple naps. But four months is also when sleep often gets harder, not easier, thanks to a major neurological shift happening in your baby’s brain.
Nighttime Sleep at Four Months
By four months, most babies are capable of sleeping 6 to 8 hours in a stretch at night, though many still wake once or twice to feed. If your baby is breastfed, nighttime wakeups tend to be more frequent than for formula-fed babies, but by this age, most infants can go five or more hours between feedings overnight. Waking to feed more than twice per night at four months may signal a habit rather than a hunger need.
Bedtime for a four-month-old typically falls between 7:00 and 8:00 PM, with a morning wake time around 6:00 to 7:00 AM. The exact timing matters less than consistency. Babies this age are starting to develop a circadian rhythm, so a predictable bedtime routine helps signal that it’s time for a longer stretch of sleep.
How Naps Should Look
Four-month-olds generally take three to four naps per day, totaling roughly four hours of daytime sleep. Don’t expect uniformity. A typical day might include a mix of two shorter naps (30 to 60 minutes) and one or two longer ones (1 to 2 hours). Some babies are consistent nappers; many are not at this age, and that’s normal.
The time your baby can comfortably stay awake between naps, often called a wake window, runs about 1.5 to 2.5 hours. These windows tend to be shortest in the morning and longest before bedtime. A rough pattern might look like this:
- Before the first nap: 1.5 hours awake
- Before the second nap: 1.75 hours awake
- Before the third nap: 1.75 hours awake
- Before the fourth nap (if needed): 2 hours awake
- Before bedtime: 2 to 2.5 hours awake
If your baby is fussy and fighting a nap after only an hour awake, they may be overtired from the previous wake window. If they’re happily playing past the two-hour mark and resisting sleep, they may need a slightly longer window. Watch your baby’s cues (rubbing eyes, yawning, turning away from stimulation) rather than strictly following a clock.
The Four-Month Sleep Regression
If your baby was sleeping reasonably well and suddenly isn’t, you’re likely in the middle of the four-month sleep regression. This is one of the most common reasons parents search for sleep information at this age, and it’s rooted in biology, not behavior.
Around four months, a baby’s brain undergoes rapid development that changes how it cycles through sleep stages. Newborns essentially have two sleep stages: active and quiet. At four months, the brain begins transitioning to a more adult-like pattern with multiple distinct stages, including lighter phases of sleep. The process of forming and linking different areas of the brain and nervous system creates instability, which means your baby wakes more easily between cycles and may struggle to fall back asleep.
This regression typically lasts two to six weeks. During this time, you might see more frequent night waking, shorter naps, increased fussiness at bedtime, and changes in appetite. It feels like a step backward, but it’s actually a sign of normal neurological development. Your baby isn’t unlearning how to sleep. Their brain is reorganizing how sleep works, and it takes time for the new system to stabilize.
Physical Changes That Affect Sleep
Four months brings a cluster of motor milestones that can disrupt sleep patterns. Your baby is learning to hold their head steady without support, push up onto their forearms during tummy time, swing at toys, and bring their hands to their mouth. These new abilities are exciting for your baby’s brain, and practicing them (even involuntarily) can wake them during lighter sleep stages.
Rolling is the big one to watch for. Some babies begin rolling around four months, which raises a safety question. If your baby is still swaddled and starts showing signs of rolling, it’s time to stop swaddling. A baby who rolls onto their stomach while wrapped can’t use their arms to reposition, which increases the risk of suffocation.
Safe Sleep Setup
The American Academy of Pediatrics guidelines are straightforward: place your baby on their back for every sleep, in their own sleep space, with no other people. Use a crib, bassinet, or portable play yard with a firm, flat mattress and a fitted sheet. Nothing else should be in the sleep space: no loose blankets, pillows, stuffed animals, or crib bumpers.
Avoid letting your baby sleep in a swing, car seat (when not traveling), bouncer, or on a couch or armchair. These positions can cause a baby’s head to fall forward, restricting their airway. Even if your baby falls asleep in a car seat during a drive, transfer them to a flat sleep surface when you arrive. Breastfeeding, if possible, is also associated with reduced risk of sleep-related infant death.
When Sleep Totals Fall Outside the Range
The 12-to-16-hour range is broad for a reason. Some four-month-olds genuinely need closer to 12 hours; others need closer to 16. The better indicator of whether your baby is getting enough sleep is how they act when awake. A well-rested four-month-old is alert, interested in their surroundings, makes eye contact, and has periods of happy, engaged wakefulness. A chronically overtired baby tends to be fussy, difficult to settle, and paradoxically harder to get to sleep.
If your baby consistently sleeps fewer than 12 hours in a 24-hour period and seems irritable or difficult to console, or if they’re sleeping significantly more than 16 hours and seem lethargic or hard to wake for feedings, those patterns are worth raising with your pediatrician. For the vast majority of four-month-olds, though, sleep is messy, variable from day to day, and in the process of reorganizing itself. The rough patch at this age is one of the most well-documented phases in infant development, and it does pass.