If you have not already done so, please read Blog Posts 1 through 5 that describe how sleep is important and beneficial. I will post specific information for parents and children based on my book, “Healthy Sleep Habits, Happy Child.” Please do not be put off by my book’s length. This is a reference book. Read only the topic of interest to you.
Within the brain, there are nerve cells that produce neurochemicals called ‘hypocretins’ that regulate wakefulness. The production pattern of hypocretins fluctuates over a 24-hour period. More hypocretins during the day creates a circadian wake drive that is separate from the circadian sleep drive. Wakefulness and sleepiness do not operate like a single electric light bulb dimmer switch that creates more light or more darkness. Rather, there are separate drives for wake and sleep states.
For example, as described by Professor Jamie Zeitzer, many shift workers can readily fall asleep during the day when their shift ends. But they have an inability to sleep for extended periods during the daytime following a night shift (even though they might be exhausted from being awake, even for 24 hours!) because during the day the circadian wake signal messes up their ability to stay asleep. The circadian wake drive is strong in the late evening and helps counter increasing drowsiness at the end of the day, so adults have difficulty napping in the late evening during the ‘forbidden zone’ (Blog Post 94). In adults, the circadian wake drive increases throughout the day and offsets the increasing sleep drive throughout the day so that a single long bout of wakefulness occurs.
Infants and preschool children do not have a single long bout of wakefulness during the day; they nap. What controls infants’ bouts of wakefulness? Do ‘wake windows’ have a biological basis? In this age range, the neurological control over the duration of wakefulness is unknown.
In the sleep literature, the metaphor of a ‘window’ that opens and closes is sometimes used to describe the beginning and ending of these bouts. For example, from the 3rd edition of my book (1987): “During the day, within a one- to two-hour time “window” of wakefulness, your baby will become drowsy and want to go to sleep. I discovered this window during my research on naps.” Some parents misinterpreted this to mean that they should always keep their baby up 1-2 hours after night sleep or after a nap. In subsequent editions, I clarified that this is the maximum time babies can comfortably stay awake. Here are more findings from my research on naps:
| Age (months) | Hours napping (per day) |
| 6 | 1-6 |
| 12 | 1.5-5.5 |
| 18 | 1.5-4 |
| 24 | 1-4 |
Children who take long naps at 6 months tend to maintain long naps until 21-24 months and this is also true for children who take intermediate and short naps (‘Individual stability’ of nap duration). Older children’s nap durations shows no individual stability. Then, children may vary from day-to-day in their total number of hours napping.
| Age (months) | 1 nap/day | 2 naps/day | 3 naps/day |
| 6 | 0 | 84% | 16% |
| 12 | 17% | 81% | 2% |
| 18 | 77% | 23% | 0 |
| 21 | 88% | 12% | 0 |
Young infants might take 2 naps on one day and 3 naps on another day or when older, take 1 nap on one day and 2 naps on another day.
| Age (months) | Number of naps taken (per week) |
| 24 | 7 |
| 36 | 6 |
| 48 | 5 |
| 60 | 4 |
At any age, a child might take many or a few naps per week depending on family circumstances.
So, for all children, there is much variability in the duration of a single nap, the total number of hours napping per day, the number of naps taken per day, and the number of naps taken per week.
My opinion is that paying attention to Drowsy Signs (Blog Posts 9 and 83) that signal the time when soothing to sleep should occur for naps (Blog Posts 53–56, 110, and 118) and bedtime (Blog Posts 123 and 139) is superior to paying attention to a clock and chart describing so-called ‘wake windows’.
Schedules of ‘Wake Windows’ are supposedly designed to help parents determine when to put their child to sleep. However, children who take longer naps can stay awake longer than children who take short naps. The large variability in napping means there is no benefit in watching a schedule of so-called Wake Windows. There is no scientific evidence to support the validity of published ‘wake windows’ schedules. ‘Wake Windows’ are fake.
I have a question about wake windows or awake time for you! i’ve been going through your book again and would ask for some clarification. we have a just turned 12 month old who has been really fighting her second nap. In your book and in general I know it is not good to wake babies from a nap. However, it does mention maybe needing to cap a nap to protect the second nap of the day. She sleeps 12 hours (without waking at all the majority of the time) from 8pm-8am. (i know ideally you recommend a 7p-7a schedule but this schedule works best for us). After she sleeps all night, she usually only wants 1.5 hours of awake time before her first nap (she starts to get fussy and yawn around this time) but I feel like she should be able to stay awake longer, especially after quality sleep. She then doesn’t fall asleep till about 4 hours after she wakes from that nap (I have experimented with capping around 1 hour. If left to sleep she sleeps 1.5-1.75 hours but then makes her second nap too late in the day). I’ve tried putting her down anywhere from 2-4 hours after her first nap and she does not fall asleep (is usually content in her bed). She puts herself to sleep just fine and has self soothing skills. Is 4 hours too long for a 12 month old? Any recommendations? If I try to stretch her wake time for the first nap she still seems to gravitate toward a longer wake time. I’m usually waking her from her second nap to protect bedtime because it’s taking her so long to fall asleep. I’m often trying to put her down by 2-3 at the latest so within the time you recommend. Could it be she’s ready for 1 nap? Anyways, thank you for your time!
Please explain in detail why this “works best for us” in “She sleeps 12 hours (without waking at all the majority of the time) from 8pm-8am…this schedule works best for us.”
due to the schedule of our family/work/and other sibling routine this is what is needed!
Understood. Many babies transition to a single nap between 12-15 months of age. You might consider doing so by incrementally delaying her first nap so that it is eventually moved to a mid-day time slot and not let her take a second nap. The well-rested child might accomplish this in several days but the over-tired child might take much longer. I think your child appears to be well-rested so you might consider doing this quickly. During the transition, the bedtime temporarily might have to be much earlier but once you have settled the nap in the midday, it might be moved to a later hour. However, once she is taking a single nap a day, because of less total day sleep, 8pm might be too late. Watch for drowsy signs in the late afternoon and early evening. The new bedtime might have to 7:30 or 7:45 instead of 8PM. On the other hand, if she has a very long single nap or wakes up later in the morning, 8PM might be fine. Does this help?
yes, that makes sense! she sometimes does a single nap on church days (church falls during naptime) but only takes about a 2 hour afternoon nap. on those days we have no problem being able to move bedtime a little earlier! she then will sleep 13-13.5 hours at night (which always seems funny to me because she fought a nap!). With an 8 am wake time, do you have a recommendation to aim for naptime over the next few days? It took her over an hour to fall asleep for her second nap (She was happy in her crib the whole time). So maybe she just isn’t tired enough? thanks again!
Sorry, there is so much individual variability. The better her night sleep (maybe, the earlier the bedtime) the faster you will be able to move the single morning nap towards the midday. Expect trial and error to result in some days that are messy!
or is there a chance i’m missing her sleepiness to put her down for her second nap much sooner? It feels like she isn’t tired 1-2 hours after her first nap, but do you find many 12 months old will nap again that soon?
Hi Dr. Weissbluth, not sure you have time for this but figured I’d reach out b/c I’m desperate.
My 16-month old was sleeping well for a long time (with the occasional night waking) since we sleep trained according to the methods in your book when she was 6 months old (we used unmodified extinction and it worked in 3 nights).
Recently, she was showing all signs of readiness to transition from 2 naps to 1 (a single night waking became the norm, shorter naps, extreme resistance to the 2nd nap to the point of often skipping a second nap, early morning wakings between 4-6am, & split nights).
However, we began the transition almost 2 weeks ago and it’s been very difficult: she’s still experiencing night wakings, fights bedtime and cries a lot even with soothing, and the 1 nap doesn’t seem to be long enough (usually 1-1.5hrs), even though she’s always put to sleep in a dark crib. Last night she woke up an astounding 5 times during the night, which was shocking (not sure that ever happened since we sleep-trained at 6 months old) and led me to believe she could be over-tired. However, I usually put her to bed between 6 and 7pm.
She is a pretty calm baby with a good temperament and her drowsy signs have always been difficult to detect. “Staring” seems to be normal for her and not necessarily a sign of drowsiness. This is why the idea of “wake windows,” (while allowing for flexibility based on recent sleep history and the few drowsy signs she does give) have helped me a great deal.
However, her nap has not yet extended consistently to the recommended 2-3 hours, so I’m concerned that she’s becoming overtired with a longer wake window in the evening before bed (~5 hours). Currently aiming for a 6:15pm start of her wind-down routine and 7pm asleep at the latest. She wakes up in the morning between 6 and 7:30am. I have a detailed log of all of her sleep since the 7th of this month. So I can provide more info if any more details would be helpful.
Other notes that could be relevant:
– She is still reliant on about 15 minutes of soothing from us at the end of her bedtime routine: holding her in the dark with rocking and drinking milk from a bottle for about half the time. Not sure if this is a problem. I’d like to wean her off of using the bottle soon.
– She’s still not walking on her own yet.
– She struggles with constipation which sometimes disrupts her sleep.
Overall I’m very confused and exhausted from the night wakings. I’m wondering if I need to throw out everything I think I know about wake windows. Not sure why it’s so difficult for me to detect her drowsiness; I think I’m pretty attentive to her and we don’t have a TV or let her watch any screens, ever. Any advice is greatly appreciated!
Sometimes, when a child transitions from 2 naps to 1 nap, the bedtime temporarily needs to be moved earlier because less sleep during the day makes her sleepy earlier in the evening. Even as early as 5:30pm. For your daughter, 6pm might be fine and 7pm way too late. Or maybe 5:30pm should be tried for a few nights. It’s trial and error and you monitor the the latency to sleep onset as a guid to whether it is too early. if it is too early she will take longer to fall asleep. Does this help?
Children with intelligent eyes often stare because they have superior IQ and everything fascinates them. In contrast, Drowsy Max (watch Blog Post 115X) is not focusing with his eyes. What do you think?
Is her pediatrician concerned about her not walking freely yet?
How do you feel about holding her for about 15 minutes at night as you describe? Does the father sometimes do this?
Thanks for your response. We will try 5:30pm bedtime and see how that goes. Last night she went into the crib at 7:05pm and we let her cry for almost an hour until she fell asleep. She only woke up once (right before midnight – this time of night waking also seems somewhat consistent) and went down easily with some comforting from her dad.
I watched the “drowsy Max” video; I think that is somewhat helpful. I’ve never seen her ‘bob’ her head like Max, and I don’t think she regularly has the lack of focus to the degree that Max does, but she does a bit. Her main drowsy cues seem to be irritability and clinginess. She seems VERY sensitive to light; once put in a dark room, it becomes more clear whether she’s tired: she will scream and resist if not (she knows that darkness means we’re trying to put her down for a nap), but if she is tired, she will settle down within a minute or two, cling to us more, and start closing her eyes.
Thankfully, our pediatrician is not concerned about her not walking freely yet. All other developmental milestones have been normal.
Holding her for about 15 minutes at night is fine with me; my only concern is her reliance on the milk bottle – usually she sucks (and actively swallows) for about half of that 15 min before spitting the bottle out. If I try to take the bottle away earlier, she becomes fussy, sometimes even starts screaming. I let her nurse to sleep all the time before she was sleep-trained at 6 months old, so she still has the suck to sleep association. The bottle use concerns me because I know it has the potential to increase the risk for tooth decay, among other health risks. Her father frequently does the 15 min “bouncing” as well – in fact, it seems that she goes down more easily with him. Sometimes it seems that she is slightly less distressed when he puts her down in the crib drowsy but awake.
I’ve also read that the transition from 2 naps to 1 can take 2 to 4 weeks to “settle into” — I think primarily meaning that it can take that long for the single nap to lengthen. Would you agree with that?
“The bottle use concerns me because I know it has the potential to increase the risk for tooth decay”: Ask your pediatrician about gradually diluting the bottle towards water only.
“Her father frequently does the 15 min “bouncing” as well – in fact, it seems that she goes down more easily with him: For the next few weeks, ask him do it more and this transition might go faster.
“I’ve also read that the transition from 2 naps to 1 can take 2 to 4 weeks to “settle into”: Every child is different; watch you infant and ignore what you read.