Night waking at 20 months is extremely common and almost always tied to a predictable set of developmental changes happening all at once. Your toddler’s brain is exploding with new language, new emotions, and a growing sense of independence, and all of that mental activity spills over into sleep. The good news: most of these disruptions are temporary, and understanding what’s behind them makes them far easier to manage.
The 18-to-24 Month Sleep Regression
Twenty months sits right between two well-known sleep regressions. The first typically hits between 14 and 19 months, driven by separation anxiety, the language explosion, new walking and climbing skills, and the shift from two naps to one. The second arrives closer to age 2, when toddlers develop a fierce desire for independence, start testing boundaries, and gain enough language to stall bedtime with requests for water, another story, or a trip to the potty. At 20 months, your child may be experiencing the tail end of one regression, the beginning of the other, or a blend of both.
What makes this age especially tricky is that so many changes overlap. Your toddler’s brain is processing new words constantly, sometimes even practicing sounds in the crib at night. Physical skills like climbing create excitement that makes settling down harder. And the emotional development that fuels separation anxiety peaks between 15 and 18 months but can easily linger into the 20-month range.
Separation Anxiety and Nighttime Fear
Separation anxiety is one of the most powerful sleep disruptors at this age. It affects nearly all toddlers to some degree, and it often looks different at night than during the day. A child who separates easily at daycare may still scream with genuine terror when left alone in a dark bedroom. Around 20 months, toddlers also begin developing the capacity for imagination, which means some children start experiencing early nightmares or a vague sense of fear they can’t yet articulate.
If your toddler wakes crying and reaches for you, or fights bedtime with increasing panic, separation anxiety is a likely culprit. What helps is building familiarity and trust around the bedroom during waking hours. Spend active time playing in the room, practice brief separations where you leave and return while calmly saying “I’ll be right back,” and offer consistent reassurance that you’re still nearby even when they can’t see you. The goal is to make the bedroom feel safe and predictable rather than like a place where you disappear.
Teething Pain From Molars
First molars typically come in during the period surrounding 20 months, and unlike the front teeth your child cut earlier, molars cause significantly more pain and inflammation. That discomfort feels worse when lying flat because blood flow to the head increases in a horizontal position, putting more pressure on already swollen gums. If your toddler is drooling more than usual, chewing on objects, fussy during the day, or losing interest in food, teething is probably contributing to the night waking.
Second molars arrive a bit later, usually between 23 and 33 months, so if your child is on the early side of development, those could be starting to move beneath the gums as well. Teething pain tends to come and go in waves, which explains why your toddler may sleep fine for a few nights and then suddenly wake multiple times.
Night Terrors vs. Nightmares
Around this age, some toddlers begin having nightmares or night terrors, and the two look very different. Nightmares happen during dream sleep and are most common in the early morning hours. Your child wakes up scared but aware, recognizes you, and may have trouble going back to sleep because the fear lingers. Night terrors happen in the first half of the night. Your child may scream, sweat, and appear terrified, but they’re not fully awake. They won’t recognize you, they’re difficult to comfort, and they won’t remember the episode in the morning.
Night terrors are more alarming to watch than nightmares, but they’re generally harmless. The best response is to stay nearby and make sure your child doesn’t hurt themselves, without trying to wake them. Nightmares, on the other hand, call for comfort and reassurance. Both tend to decrease as your toddler’s brain matures.
Nap Transitions and Schedule Shifts
Most toddlers transition from two naps to one nap between 14 and 18 months, but readiness matters more than age. If your 20-month-old recently dropped a nap or is in the middle of that transition, their sleep schedule may be temporarily thrown off. Signs that the transition is causing problems include resisting the second nap, taking shorter naps than usual, waking early in the morning, or lying awake for long stretches in the middle of the night.
If your child is regularly getting less than 10 hours of sleep per night on a two-nap schedule, moving to one nap may actually help lengthen nighttime sleep. During the transition, you may need to shift bedtime earlier to compensate for the lost daytime sleep. Toddlers between 12 and 24 months need 11 to 14 total hours of sleep in a 24-hour period, including naps.
Room Environment and Bedtime Habits
Small environmental factors can make a big difference. The ideal bedroom temperature for toddlers is between 68 and 72°F, slightly warmer than what’s recommended for adults, because young children haven’t fully developed the ability to regulate their own body temperature. A room that’s too warm or too cold can cause restless sleep and repeated waking without an obvious cause. Keep the room dark and quiet, and consider white noise if outside sounds are an issue.
Screen time in the hour before bed suppresses your toddler’s natural sleep hormones. Turning off all screens at least one hour before bedtime gives their brain time to wind down and prepare for sleep.
Building a Routine That Reduces Night Waking
Children who follow a consistent bedtime routine fall asleep faster, sleep longer, and wake less during the night. The routine doesn’t need to be elaborate. Three or four activities done in the same order every night is enough: a small snack, brushing teeth, putting on pajamas, and reading a book, for example. The whole routine should take about 30 minutes, or slightly longer if you include a bath.
A few details make the routine more effective. Start before your toddler is overtired, because overtired children become hyperactive or irritable and have a harder time falling asleep. Dim the lights in the house as you begin winding down. End the routine with a goodnight kiss and leave the room while your child is drowsy but still awake. This last part matters because toddlers who fall asleep independently are better at putting themselves back to sleep when they naturally wake between sleep cycles during the night.
Consistency is the most important element. Doing the same routine in the same order every night creates a predictable signal that sleep is coming, which reduces resistance and anxiety. On nights when teething pain, separation anxiety, or a developmental leap disrupts things, the routine itself becomes an anchor your toddler can rely on even when everything else feels unsettled.