Six months is one of the most common ages for sleep to fall apart, even for babies who were previously sleeping longer stretches. The reasons stack on top of each other: your baby’s brain is developing rapidly, their body may be cutting teeth, and they’re becoming aware of your absence in a way they weren’t before. Most of these causes are temporary and normal.
Their Sleep Cycles Are Shifting
Babies cycle between light and deep sleep multiple times each night, just like adults. The difference is that when your baby passes from deep sleep back into light sleep, they often wake up fully. In the first few months, many babies could drift through these transitions without much trouble. By six months, increased brain activity and awareness of their surroundings make those transitions harder to navigate quietly.
If your baby falls asleep while being rocked, fed, or held, they expect those same conditions when they surface into light sleep. Finding themselves alone in a dark crib feels wrong, so they cry. This is sometimes called a “sleep association,” and it’s the single most common reason six-month-olds wake repeatedly. Babies who learn to fall asleep in the crib at bedtime tend to resettle more easily when they wake between cycles, because the environment matches what they expect. Research from the UK has shown that some infants can resettle themselves after waking as early as three months, but many six-month-olds still need help building that skill.
New Skills Keep Their Brain Buzzing
Around six months, babies are learning to sit up, starting to figure out crawling, and babbling more. These milestones are exciting for their developing brain, and that excitement doesn’t shut off at bedtime. You may notice your baby practicing sitting or rolling in the crib at 2 a.m. instead of sleeping. This is a classic sign of a developmental leap disrupting sleep.
The most significant cognitive shift at this age is the beginning of object permanence, the understanding that things still exist even when they’re out of sight. Before this clicks, a baby who couldn’t see you simply didn’t think about you. Now they know you’re somewhere, and they want you back. This new awareness fuels separation anxiety, which typically begins between 6 and 12 months and can make bedtime and middle-of-the-night wakings more emotional. Your baby may cry harder and longer when you leave the room, or insist on having you next to them to fall asleep.
Teething Pain Peaks at Night
Six months is when teething commonly starts, and the discomfort tends to feel worse at night when there are no daytime distractions. Signs that teething is behind the wake-ups include red, swollen gums where a tooth is pushing through, excessive drooling, gnawing on anything within reach, a flushed cheek, ear rubbing, and general fussiness. A mild temperature below 100.4°F (38°C) can also accompany eruption.
Teething pain usually comes in waves around each tooth, so it won’t disrupt sleep every single night for months. If your baby has been waking frequently for weeks with no signs of gum swelling or new teeth, something else is likely the primary cause.
They May Not Need Night Feeds Anymore
By six months, most babies no longer need calories overnight to support their growth. UCSF Benioff Children’s Hospitals notes that while many six-month-olds still wake to eat, they’re waking out of habit rather than hunger. At this age, a baby typically drinks 6 to 8 ounces of formula or breast milk at each feeding, across four or five feedings in a 24-hour period. As long as they’re getting enough volume during the day (roughly 2.5 ounces per pound of body weight, up to about 32 ounces total), nighttime feeds are optional.
That said, some babies genuinely still need one feeding overnight, especially breastfed babies or smaller infants. The key distinction is between a baby who wakes once, eats a full feed, and goes back to sleep versus a baby who wakes every one to two hours and only nurses or takes a bottle for a few minutes before dozing off. The second pattern points to a feeding-to-sleep association rather than true hunger.
Wake Windows and Overtiredness
A six-month-old typically needs 2 to 3 hours of awake time between sleep periods. Those windows usually get longer as the day goes on, so your baby might only handle 2 hours of wakefulness before the first nap but need closer to 3 hours before bedtime. When babies stay awake too long, their bodies produce stress hormones that make it harder to fall asleep and stay asleep. The result is a paradox: an overtired baby actually sleeps worse, not better.
Undertiredness causes problems too. If your baby is still taking three long naps and going to bed early, they may not have enough sleep pressure built up to stay asleep through the night. Many six-month-olds are in the process of transitioning from three naps to two, and that transition period can temporarily throw off nighttime sleep. If your baby is fighting bedtime or waking very early in the morning, their daytime schedule may need adjusting.
The Room Itself Might Be the Problem
The American Academy of Pediatrics recommends keeping your baby’s room between 68 and 72°F, though some evidence suggests the ideal range may actually be a bit lower, between 60 and 67°F. Overheating is a common and underappreciated cause of restless sleep. If your baby is sweating or their chest feels hot to the touch, they’re too warm. Dress them in one layer more than you’d wear comfortably in the same room, and skip blankets entirely.
Humidity between 30 and 60 percent is the healthy range, with some experts recommending the higher end (around 55%) for babies, especially in dry climates or heated rooms during winter. Dry air can irritate nasal passages and make breathing uncomfortable enough to cause wake-ups. A simple humidifier can make a noticeable difference.
The crib should have a firm, flat mattress with a fitted sheet and nothing else. No blankets, pillows, bumper pads, or stuffed animals. Beyond being a safety issue, loose items in the crib can actually contribute to wake-ups by covering your baby’s face or getting tangled around their limbs.
What Actually Helps
Start by looking at the full picture rather than assuming one cause. If your baby is drooling excessively and has swollen gums, address teething comfort. If they only fall asleep while being fed or rocked, work on putting them down drowsy but awake so they can practice falling asleep independently. If their room is too warm or their nap schedule is off, fix those first, because no sleep training method works well when the environment or timing is wrong.
A consistent bedtime routine signals to your baby’s brain that sleep is coming. Keep it short (10 to 15 minutes) and predictable: a feed, a book, a song, then into the crib. Do the last feeding at the beginning of the routine rather than the end, so your baby doesn’t associate falling asleep with eating.
For separation anxiety, brief check-ins where you reassure your baby without picking them up can help them learn that you always come back. This phase is hardest on parents emotionally, but it does resolve on its own, typically by age 3 though the most intense period at night usually passes within a few weeks to months.
Most six-month-olds are capable of sleeping longer stretches. The fact that yours isn’t right now doesn’t mean something is wrong. It usually means their brain is doing exactly what it should be doing, just at an inconvenient hour.