Few things feel more counterintuitive than waking a sleeping baby. You may have spent twenty minutes feeding, rocking, walking or negotiating with the universe to get them to sleep, and now somebody is suggesting that you deliberately wake them up.
I understand the reluctance. If your baby is sleeping peacefully, there is usually no reason to wake them simply because a schedule says the nap has lasted long enough. Babies vary considerably in how much sleep they need and in how they distribute that sleep across the day and night. Some naturally take short naps, while others sometimes sleep for much longer stretches.
But there are situations where I do suggest looking at the length or timing of a nap. Not because long naps are inherently bad, and certainly not because daytime sleep needs to be controlled down to the minute. The question is much more practical: is this particular nap still working well within your child’s whole twenty-four-hour sleep pattern?
Start with the whole day, not one nap
When parents ask me whether they should wake their baby, I rarely answer based on the nap alone. I want to know what happens before and afterwards.
How old is your baby? How much do they sleep across twenty-four hours? When does the day usually begin? How many naps are they taking? What time does this nap happen? Is bedtime easy, or has it become a forty-five-minute project? What happens overnight? Is your baby waking happily after the nap, or do they seem as though they desperately needed the sleep?
This is important because there is no ideal nap length that applies to every baby. Research gives us averages and ranges, but you do not live with an average baby. Sleep need, timing and nap patterns vary substantially between children, and they continue to change as babies develop.
A two-hour nap can fit beautifully into one child’s day and make another child’s bedtime increasingly difficult. The number itself does not tell us whether there is a problem.
Do long naps ruin nighttime sleep?
Not automatically.
You may have heard some version of never wake a sleeping baby, or the opposite advice that you should cap naps so your baby saves their sleep for nighttime. Neither rule is particularly useful on its own.
Sleep is regulated partly by sleep pressure: broadly speaking, the longer we are awake, the greater the biological drive towards sleep becomes. Sleeping reduces that pressure. So yes, daytime sleep and nighttime sleep are related. But this does not mean that every hour your baby sleeps during the day is an hour stolen from the night.
Babies need daytime sleep. Young babies in particular distribute sleep across the entire twenty-four hours rather than neatly separating it into a long night and a small number of predictable naps. Their circadian system and sleep architecture are still developing, and substantial daytime sleep is completely ordinary.
As babies become older, however, the distribution matters more. If a long or late nap is repeatedly followed by a very difficult bedtime, a short night or a long period awake in the middle of the night, then I would become interested in whether that daytime sleep is affecting the rest of the pattern.
What if my baby takes one enormous nap?
First, I would ask whether anything is actually going wrong.
If your baby takes a long lunchtime nap, goes to bed easily, sleeps reasonably well at night and seems happy and rested, I would be reluctant to interfere simply because somebody else’s schedule says the nap should be shorter.
If, on the other hand, your toddler sleeps for three hours in the afternoon and then spends an hour and a half bouncing around the bedroom at bedtime, that long nap becomes more interesting. The same applies if your child is regularly wide awake for an hour or two during the night. In the Handbook, this is exactly why I look at the whole twenty-four hours when a child has repeated split nights rather than concentrating only on what happens at 2 a.m.
Sometimes shortening a particularly long nap a little can make more room for nighttime sleep. That is very different from routinely waking every baby after an arbitrary number of minutes.
Very young babies are different
I am much more cautious about deliberately limiting sleep in newborns and young babies.
At this age, there may be no recognisable schedule at all. Feeding, sleeping and short periods of alertness can overlap throughout day and night. One day may contain many short sleeps; another may contain several substantial ones. Some babies spend much of the day drifting between feeding and sleep against somebody’s body.
There are also situations in the early weeks when you may need to wake a baby for feeding for medical or feeding reasons. A newborn who is not feeding effectively, has not regained birth weight as expected, is unusually sleepy or has other health concerns needs individual guidance from an appropriate healthcare professional. This is not really a sleep-scheduling question.
For a healthy young baby who is feeding and growing well, however, I would not routinely interrupt a perfectly good sleep simply to make their day fit a sleep chart.
What about day and night confusion?
This is one situation where parents sometimes wonder whether they should wake a young baby who seems capable of sleeping all afternoon and then holding a small social gathering at midnight.
The circadian system is still developing in early infancy, so day and night can genuinely be rather muddled. But I would not respond by trying to exhaust your baby during the day.
Instead, let daytime contain ordinary opportunities to wake. When the walk is finished, you do not necessarily have to leave your baby sleeping in the pram for another two hours because waking them feels forbidden. Take them out of the carrier when you get home. Offer milk. Change their nappy. Open the curtains. Go outside. Let daytime contain light, movement, feeding, contact and normal household transitions.
If they wake and are still sleepy, you can help them sleep again. The aim is not to deprive them of sleep. It is simply to let day feel like day while their biological rhythm develops.
Nap transitions change the picture
There are periods when a nap that worked perfectly well for months suddenly begins interfering with something else.
Perhaps your baby has been taking three naps, but the third is now becoming almost impossible to fit in without pushing bedtime very late. Perhaps your older baby still takes two good naps but increasingly resists the second. Or your toddler sleeps beautifully at lunchtime and then seems nowhere near ready for bed at the time that used to work.
This is often how nap transitions begin. They do not necessarily happen overnight, and the fact that a child is approaching a transition does not mean you need to eliminate a nap immediately.
There may be weeks when the nap happens on some days and not others, or when it needs to become shorter before it disappears. If bedtime and nighttime sleep are becoming increasingly difficult while daytime sleep remains substantial, gently limiting one nap can sometimes be part of that transition.
The goal is not to force your baby onto the next schedule. It is to notice when the old pattern is no longer fitting comfortably.
Should I wake my baby to protect bedtime?
Sometimes, yes.
If a late-afternoon nap begins at 5 p.m. and your older baby normally goes to bed around 7:30, allowing that nap to continue for two hours will obviously change the evening. That is not because sleeping after five is biologically forbidden. Your baby simply cannot be expected to wake from a substantial sleep and immediately have enough sleep pressure to start another substantial sleep.
In that situation, I might allow a shorter nap and then see what happens. Perhaps twenty or thirty minutes is enough to bridge the gap to bedtime without turning the nap into the beginning of the night.
But again, watch your baby rather than obeying the clock. If shortening that nap leaves them miserable for the entire evening and bedtime becomes worse rather than better, that is useful information too.
What if my baby is catching up after a bad night?
This is where I would be particularly reluctant to apply rigid nap caps.
If your baby was ill, travelling, awake unusually often or simply had a dreadful night, they may genuinely need more sleep the following day. Recovery sleep is not a scheduling failure.
One longer nap after a difficult night is very different from a pattern in which long daytime sleeps, late mornings and long night wakings begin reinforcing one another. Look for a pattern before trying to correct one unusual day.
Babies are allowed to have strange days. Adults do too.
So when would I consider waking a baby?
I would consider it when there is a reason rather than because a generic schedule tells me to. Perhaps a very long nap is consistently making bedtime difficult. Perhaps a late nap is pushing the whole evening later. Your child may be moving through a nap transition, or repeated long daytime sleeps may be part of a pattern of split nights or increasingly short nights.
There may also be practical reasons. You have to collect another child from school, go to childcare or leave the house. Your baby’s sleep exists inside family life. You do not need to organise the entire household around preserving every nap to its natural conclusion.
What matters is the overall pattern and how your child responds.
Before you wake the baby
If everything is working, I would leave it alone.
That sounds almost ridiculously simple, but baby sleep advice has a remarkable ability to turn something that is working into a problem because it does not match somebody else’s timetable.
If your baby takes a long nap and still sleeps well at night, there is nothing obviously wrong with the nap. If they take short naps and seem perfectly well, those naps still count as sleep. If a nap has started pushing bedtime later or contributing to long periods awake at night, then we can experiment with its timing or length.
You do not need to wake a sleeping baby to produce a perfect schedule. Sometimes you may wake them because, looking at the whole twenty-four hours, that particular sleep is no longer happening in the most useful place.
Research
Galland BC, Taylor BJ, Elder DE, Herbison P. (2012). Normal sleep patterns in infants and children: a systematic review of observational studies. Sleep Medicine Reviews, 16(3), 213–222.
Paavonen EJ, Saarenpää-Heikkilä O, Morales-Muñoz I, et al. (2020). Normal sleep development in infants: findings from two large birth cohorts. Sleep Medicine, 69, 145–154.
Staton S, Rankin PS, Harding M, et al. (2020). Many naps, one nap, none: a systematic review and meta-analysis of napping patterns in children 0–12 years. Sleep Medicine Reviews, 50, 101247.