A 4-month-old should sleep 12 to 16 hours per 24-hour period, including nighttime sleep and daytime naps. That’s a wide range because every baby is different, and four months is a particularly transitional age for sleep. Your baby’s brain is in the middle of major changes that affect how, when, and how well they sleep.
How Those Hours Break Down
Most of the sleep happens at night, with a longer stretch that may reach five or more hours without a feeding. During the day, expect two to three naps totaling roughly three to four hours combined. Some babies consolidate into longer naps at this age while others still take shorter ones scattered throughout the day.
Wake windows, the time your baby can comfortably stay awake between sleep periods, run about 1.5 to 2.5 hours at four months. That includes feeding, playing, and any other activity. Pushing past that window often leads to overtiredness, which paradoxically makes it harder for your baby to fall asleep.
Why Sleep Changes at 4 Months
Four months is when your baby’s internal clock starts to come online. The pineal gland, which produces the sleep hormone melatonin, isn’t functional at birth. It begins synthesizing melatonin between 4 and 6 months of age. Stable circadian rhythms for sleep, body temperature, and stress hormones typically develop during this window as well. In practical terms, this means your baby is shifting from the eat-sleep-eat pattern of a newborn toward more adult-like sleep cycles with distinct stages of lighter and deeper sleep.
This transition doesn’t always go smoothly. Your baby may start waking more frequently at night, fighting naps, or sleeping in shorter bursts. Several things contribute: greater awareness of surroundings leading to overstimulation, early signs of separation anxiety, and the uneven process of consolidating sleep cycles. A baby who previously slept well may suddenly struggle for a few weeks.
How Night Feedings Fit In
By four months, many babies can go five or more hours at night between feedings. One or two night feedings is still normal at this age. If your baby is waking to eat more than twice per night, it may signal a habit rather than genuine hunger, especially if they’re gaining weight well and eating enough during the day. That said, breastfed babies sometimes need slightly more frequent feeds than formula-fed babies because breast milk digests faster.
Sleep Training Readiness
Four months is generally the earliest age pediatricians consider appropriate for sleep training. At this point, babies are old enough to begin learning to self-soothe, their circadian rhythm is starting to take effect, and many no longer need to eat every few hours overnight. Sleep training before this age isn’t recommended because newborns have short sleep cycles, can’t go long stretches without food, and haven’t developed the ability to self-soothe.
Sleep training isn’t required at four months. It’s an option, not a milestone. Some families find it helpful during the four-month sleep regression, while others prefer to wait or use gentler approaches. If you’re considering it, your pediatrician can help you decide whether your baby is developmentally ready based on their weight gain and feeding patterns.
Creating a Safe Sleep Setup
The American Academy of Pediatrics recommends a firm, flat mattress in a safety-approved crib or bassinet with only a fitted sheet. No blankets, pillows, bumper pads, or stuffed animals in the sleep area. Room sharing (keeping the crib in your room) is recommended for at least the first six months.
These guidelines matter more as your baby becomes more mobile. Many babies start rolling around four months, which can change their sleep position during the night. Once your baby can roll both ways on their own, you don’t need to reposition them, but keeping the sleep surface clear of loose items becomes even more important.
Signs Your Baby Is Getting Enough Sleep
Total hours are a useful guideline, but your baby’s behavior is a better indicator. A well-rested 4-month-old is alert and engaged during wake windows, feeds well, and settles within a reasonable timeframe at nap and bedtime. A baby who is chronically short on sleep tends to be fussier, harder to settle, and may actually sleep less because overtiredness disrupts their ability to stay asleep.
If your baby is consistently sleeping fewer than 12 hours in a 24-hour period, seems excessively drowsy or irritable during waking hours, or has sudden changes in sleep that last more than a few weeks, it’s worth bringing up with your pediatrician. Short-term disruptions are normal at this age, but persistent patterns that fall well outside the 12-to-16-hour range deserve a closer look.