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.
There is a question I hear from parents in many forms, but it always comes down to the same thing: Should I put her down at nine o’clock, or wait until nine-thirty?
The question sounds reasonable. It is, in fact, the wrong question — not because timing does not matter, but because the clock is the wrong instrument for answering it. The clock does not know your child. Your child’s biology does. Your job, as a parent who wants to support healthy sleep, is to learn to read the biology and stop looking at the clock for an answer the clock cannot give.
This post is about how to do that.
What a circadian rhythm actually is
The word “circadian” comes from the Latin circa dies — approximately a day. A circadian rhythm is a biological cycle that repeats approximately every twenty-four hours, driven by an internal clock located in a small region of the brain called the suprachiasmatic nucleus. This internal clock governs not just the timing of sleep and wakefulness but the timing of cortisol release, body temperature, hormone secretion, metabolism, and dozens of other physiological processes that rise and fall across the day in predictable waves.
The critical word is internal. The circadian clock is not set by your wall clock. It is set by light, by feeding, by social cues, and most powerfully in early infancy, by the gradual maturation of the brain itself. A newborn has no consolidated circadian rhythm — it emerges over the first weeks and months of life as the suprachiasmatic nucleus develops and the baby’s biological systems begin to synchronize with the external world. By roughly three to four months, most infants have a circadian architecture that is recognizable and that begins to make the timing of sleep biologically predictable.
Predictable — but not identical across children.
Individual variation is real and large
Here is what no published schedule can account for: individual variation in circadian timing is substantial, even among children of the same age.
Two eight-month-olds can have circadian systems that differ by an hour or more in their internal timing. One child’s sweet spot for the morning nap may be nine o’clock. Another’s may be nine forty-five. One child may be able to extend her waking period before the afternoon nap to two and a half hours without crossing into pre-sleep arousal. Another child of identical age crosses that threshold at one hour and forty-five minutes and will tell you so clearly — if you are watching.
This variation is not randomly distributed. It is structured by genetics, by the child’s individual developmental trajectory and by the accumulated sleep history of the preceding days. A child who slept well last night has more flexibility. A child carrying cumulative sleepiness has less. The same child on different days may show her drowsy signs at different clock times, and both times may be correct — because the biology is responding to conditions, not following a posted schedule.
This is precisely why “wake windows” — the commercially popular concept specifying how many hours a child of a given age should be awake between sleep periods — are not a substitute for watching your child. Wake windows are population-level averages, derived from group data, presented as individual prescriptions. They may describe what is typical. They do not describe what is true for your child today. A parent who rigidly follows a wake window is watching the clock. A parent who watches the child is watching the biology. These are not equivalent.
The morning nap and the circadian architecture of early childhood
The nap structure of early childhood is not arbitrary. It follows the circadian architecture of the developing brain.
The two major naps are not interchangeable. The morning nap consolidates learning from the preceding waking period and supports the consolidating function of the afternoon nap that follows. Skipping the morning nap and hoping the afternoon nap compensates is like skipping the first movement of a symphony and hoping the second picks up the thread. The architecture has internal logic. Disrupting one part disrupts the whole.
The sweet spot: what it is and how to find it
The sweet spot is the brief window during which the child is moving from calm-alert wakefulness into the drowsy period — when sleep pressure and circadian readiness are aligned, when the brain is transitioning toward sleep naturally and the external conditions can support rather than override that transition.
It is not a clock time. It is a biological state. And it has observable signs.
The drowsy signs to look for are specific and important to distinguish from fatigue signs, which signal that the window has been missed. Drowsy signs include: a slight quieting of activity, a softening of the gaze — the eyes become less focused, not glazed but less engaged with the environment — a brief yawn that does not yet carry the irritability or rubbing of overtiredness, a slowing of movement, and a quality of calm that is distinct from the child’s ordinary calm. The child is not yet fussy. She is not yet fighting. She is in transition.
Fatigue signs are what follows when the drowsy period has passed. Rubbing eyes, pulling ears, arching the back, increased fussiness, turning away from stimulation, crying that is hard to console. These are not signs that the child is ready for sleep. They are signs that the child needed sleep fifteen minutes ago, and the second wind or the pre-sleep arousal that follows overtiredness is now making sleep harder to achieve, not easier.
The parent who waits for fatigue signs before initiating the sleep routine will consistently miss the sweet spot. The parent who puts the child down when she first seems drowsy — before the fussiness, before the arching, before the full expression of overtiredness — will find that the child settles more easily, sleeps longer, and wakes in a better state.
Stretching toward noon: the specific trap
One pattern deserves particular mention because it is extremely common and consistently produces poor outcomes: the parent who stretches the morning nap later and later in pursuit of a schedule that aligns with convenience, social life, or a published recommendation that the nap should happen closer to noon.
The logic is understandable. If the morning nap is pushed later, the afternoon nap shifts later, the bedtime can shift later, and the family can maintain a schedule that works for adult life. The biology does not cooperate with this logic.
When the morning nap is pushed past the sweet spot — past the window in which sleep pressure and circadian readiness align — several things happen. The child enters pre-sleep arousal: a state of neurological activation driven by the stress of being kept awake past the biological readiness for sleep. Cortisol rises. The child becomes harder to settle, not easier. When sleep finally comes, it is more fragmented and less restorative, because the brain entered sleep from a state of arousal rather than from the calm of the drowsy period.
The afternoon nap then shifts later to compensate, crowding the bedtime. The bedtime shifts later and produces the second wind. The child who seemed impossible to get down at eight is wide awake and apparently energetic at nine. The parent, reading this as a sign that the child is not tired, pushes the bedtime later still. The biology has been producing exactly the opposite signal — the alertness of the late evening is not evidence of adequate sleep. It is evidence that the circadian system has activated its wake-maintenance response, and the window for easy sleep onset has been passed.
The entire cascade traces back to one decision: stretching the morning nap later than the child’s biology supports.
Clock-based scheduling versus biology-based scheduling
I want to be direct about something, because there is a large commercial market in infant and toddler sleep schedules, and the schedules are presented with specificity — down to the quarter-hour — that implies a precision the underlying biology does not support.
Clock-based scheduling tells you: put your baby down at nine-fifteen for the morning nap, and at one o’clock for the afternoon nap, and at seven-thirty for bedtime.
Biology-based scheduling tells you: watch your child from roughly the time you expect the drowsy period to begin, and when you see the drowsy signs, begin the wind-down and move toward sleep.
The first approach treats the schedule as the thing to follow and the child as the variable to manage. The second approach treats the child as the thing to follow and the schedule as a rough expectation to be updated by observation.
Neither approach ignores timing. Both recognize that the drowsy period for a given child tends to fall within a predictable range. The difference is what happens at the edges of that range, when the clock says one thing and the child says another. The clock-based parent overrides the child. The biology-based parent trusts the child.
Over the span of weeks and months, the biology-based parent develops something the clock-based parent does not: genuine fluency in reading her child’s sleep signals. She stops asking whether nine o’clock or nine-thirty is correct, because she has learned that her child tells her the answer clearly, and she has learned to hear it.
What this means in practice
Watch your child, not the clock. Know the range within which her drowsy period typically falls — not to the minute. A temperamentally regular child might exhibit drowsy signs but within a 10-20 minute window, but a temperamentally irregular child might have more variation day by day when the drowsy signs appear. When you enter that range, begin winding down. Reduce stimulation. Darken the environment if possible. Hold her calmly or begin the pre-nap routine. Let the biology do what it is trying to do.
When you see the drowsy signs — the softening gaze, the quieting, the slight withdrawal from engagement — move. Not in ten minutes. Now. The window is brief. The fatigue zone follows the drowsy period, not the other way around.
If you miss it, you will know. The fussiness, the arching, the second wind — these are the biology’s way of telling you that the sweet spot has passed and that you are now working against the current. You cannot force sleep from that state. You can only wait for the arousal to subside and try again, and resolve to watch more closely tomorrow.
And tomorrow, watch the child. Not the clock.
— Marc Weissbluth, M.D.
Dear Dr. Weissbluth,
My baby is currently 10 weeks old.
I have read your book from beginning to end once, and I am now reading it again. I have also been reading your blog extensively, as well as other parents’ experiences. Since we are approaching the three-month mark, I am trying to apply the principles from your book as carefully as possible.
Since my baby was about one month old, we have established an earlier bedtime. We usually begin the bedtime routine around 5:00 p.m., and his actual bedtime varies depending on how long he nurses, since I breastfeed. Most nights, he falls asleep around 6:00 to 6:30 p.m. He usually falls asleep at the breast. After that, I hold him upright for about 10 minutes so he can burp and digest a little, as he tends to regurgitate. I then put him down swaddled. At night, he usually has no difficulty sleeping for a first stretch of 5 to 9 hours, followed by additional stretches of around 2 to 3 hours. He normally wakes up for the day between 6:30 and 7:30 a.m.
Regarding naps, ever since I read your book, I have been trying to protect them as much as possible. I usually start a nap routine after he has been awake for about 30 to 45 minutes. This has to be a very conscious effort, because my baby is not the kind of baby who simply falls asleep on his own. Even when we try to help him fall asleep in our arms, he often cries quite a bit.
I am now trying to help him sleep outside of our arms, because he almost always wakes up during the transfer from our arms to the crib or bassinet. However, it takes a great deal of soothing for him to fall asleep directly on the sleep surface. Sometimes it takes me 40 minutes to get him to sleep, and there is still a lot of crying.
His crying before sleep can be very intense — at least it seems that way to me as a first-time mother. He gets very red and sometimes seems almost to choke or gag from crying. I do not respond to every small cry, especially when it is more intermittent, but when the crying escalates to that level it is very difficult for me to assess whether I should continue or intervene.
He has been a baby with significant colic and dyschezia, and we are also investigating a possible cow’s milk protein allergy, with adjustments to my diet.
We have already made a few isolated attempts to let him fall asleep directly on the sleep surface while allowing him to cry. Today, for example, after two failed nap attempts in which he only slept for 10 to 15 minutes, I let him cry. He cried for 25 minutes and then slept for one hour. It probably would have involved less crying, but he fell asleep a few times and then woke up because of the Moro reflex. We do not use the swaddle during the day.
We are preparing to apply the full extinction method at three months, because from what I have read, I understand that it may be more effective then than if applied now. I also understand that, in order to do this properly, I will probably need to take him off the breast before he falls asleep, including at night.
I have a few questions about how to apply these recommendations.
First, what do you think about the pediatrician’s recommendation to hold him upright for about 10 minutes for burping and digestion? Do you think this could interfere with sleep training?
Second, regarding the Moro reflex, do you think it would be better to use the swaddle during sleep training, or should we remove it and use the training period as an opportunity to transition out of the swaddle?
Third, what would you consider a reasonable nursing duration before taking him off the breast? He has been gaining weight very well since we left the hospital. I have difficulty identifying a clear suck-and-swallow pattern, because sometimes, just when his sucking seems to slow down, he starts sucking strongly again.
I also think I have difficulty identifying the signs of “drowsy but awake.” I usually rely on the clock, as I mentioned above, and it often coincides with his first yawn when I pick him up to start the sleep routine. I have watched videos on your blog, but it seems to me that my baby does not show the same signs, perhaps because he is still very young.
Do you have any other suggestions for our situation?
I should also mention, because I know you often asks this, that his father is fully on board with the plan. My intention is to take the baby off the breast before he falls asleep, hand him to his father for burping, and then have him placed in the crib. We plan to start on a weekend so his father can be more present and involved.
My son is also a happy baby. He is already smiling a lot and “talking” to us. He also plays independently on his activity mat for short periods, which has become important because I have already returned to work remotely.
Thank you for your work and for everything you have shared with parents.
Kind regards.
Thank you for your detailed note.
First, many babies are happy spitters and have no GI or sleep problems. If you wish to check in with your pediatrician, or not, consider not doing this for 2-3 days and see if it makes a difference.
Second, if you think swaddling helps him sleep, do it.
Third, most healthy babies grow well with nursing for 7-10 minutes at each breast.
I also think I have difficulty identifying the signs of “drowsy but awake.” I usually rely on the clock, as I mentioned above, and it often coincides with his first yawn when I pick him up to start the sleep routine. I have watched videos on your blog, but it seems to me that my baby does not show the same signs, perhaps because he is still very young. YES, please be patient
What was his gestational age at birth?
I should also mention, because I know you often asks this, that his father is fully on board with the plan. My intention is to take the baby off the breast before he falls asleep, hand him to his father for burping, and then have him placed in the crib. We plan to start on a weekend so his father can be more present and involved.
Because of his great night sleep, be optimistic!
Dear Dr. Weissbluth,
Thank you very much for your kind and encouraging reply.
He was born at 39 weeks and 4 days.
Kind regards.
The fact that he developed excellent night sleep despite colic and the fact that your husband was pro-active in helping with baby’s sleep sleep need to be broadcasted.
My sincere goal is to raise awareness of accurate, research-based information about children’s sleep, so that more families can find their way to restful nights and calmer days. You are now on the right path, and I am confident your child’s sleep will continue to improve. Please read Blog Posts 247A-C to understand how you are helping her build a better brain; more than a million new nerve connections are made during every second of healthy sleep!
To help encourage other parents who may be struggling with the same challenges you faced, would you consider writing a narrative account of your sleep journey and posting it here as a comment? I would use it as a Blog Post. Parents often find it most meaningful to hear from other parents — what the problem looked like, what you tried, what worked, and how your family came through it. If you are willing, please include the role the father played, as father involvement is one of the most important and underappreciated factors in helping children sleep well.
If you feel comfortable doing so, an honest Amazon book review would also be a tremendous help to families who are searching for guidance and trying to decide whether this approach is right for them.
I wish you and your child sweet dreams.
Hi Dr. Weissbluth,
I’m wondering if you can help us resolve my son’s early morning wake-ups. I read your book before we sleep trained my daughter a few years ago and again before we sleep trained my son earlier this year. My daughter was a great sleeper and we never had any major issues with night wakings or early morning wake-ups, but my son is a little bit harder to figure out. We have sleep trained him 3 times using your extinction method – the first time at 4 months when suddenly he started waking up every hour all night long. We have a 2 bedroom house, so we moved my daughter out of her room and my son got to sleep in there on his own until he figured out how to sleep through the night. He did, and we moved her back into the room (so they slept in there together) about a month later. Then, sometime around six months he had a major sleep regression where he was waking up all night long again. I assume this was related to his new skill of learning how to sit up. We moved my daughter back out of the room and sleep trained him again. After about a month of him sleeping solidly through the night, we moved my daughter back in and the two slept in there together for about a month. Then, unfortunately, he started waking up all night long again around the time that he was pulling to stand. Thankfully, my daughter has remained a great sleeper and is super flexible with being moved in and out of her room. We have not moved her back in since sleep training my son for the third time (about 5 weeks ago when he was 10 months), because even though he is sleeping great through the night now, he continually wakes up at 5 AM every day. We have tried doing an earlier bedtime for him on days where he doesn’t nap very well, we have tried keeping him awake a little longer between sleeps, limiting his daytime sleep… sometimes we have one or two good days where he will sleep past 6 AM and we think we’ve figured it out, but then he goes right back to the 5 AM wake ups. He is 11 months old now and usually sleeps from about 6:30pm until 5 am. He is a great daytime napper, but we’ve learned that when he gets too much daytime sleep he has a lot more 3-6am wake ups. We don’t go in at all in the middle of the night, and usually if he wakes up, he falls back to sleep within 5-10 minutes on his own, but my husband wakes up very early for work (4:30am), so when our son wakes up at 5 AM, either my husband, or I go in there to try to keep him quiet and put him back to sleep. My husband can’t get any work done with our son screaming, since our house is very small. Also, some mornings, our son is crying so loud that our daughter wakes up, even though she is in the other room with a sound machine on in there. As you can imagine, it’s very difficult for my husband to get any work done when all of a sudden everyone is awake in the house. This has been happening for about 2 months.
I am grateful that our son is a very good night sleeper now (usually 10-11 hour stretches and he doesn’t eat during the night anymore). Also, he is a really happy boy in general. He hardly cries during the day, and is very alert and playful the majority of the time. I feel like we have done a good job of paying attention to his drowsy signs, since the majority of the time he goes down for naps and nighttime sleep very easily and completely on his own.
Can you help us figure out these early morning wake ups? Also, for context, he is usually awake for 3.5-4 hours between naps (although I try to not watch the clock, just pay attention to drowsy songs). Lastly, he just started daycare 3 weeks ago and they have been accommodating a short morning nap for him, even though all the other kids only do one nap a day. He naps for about 30 minutes in the morning, usually around 9am, and then goes down for a longer afternoon nap with the other kids around 1pm. Since starting daycare, he has been getting about 2 hours of daytime sleep between the 2 naps. When he’s at home with us, he usually naps for about 2-3 hours during the day.
Thank you so much for your help.
Because his bedtime is too late he is in a state of mild hyper-arousal causing his sleep issues: he wakes up too early, even though he needs longer night sleep and sometimes takes a short morning nap. Describe the Drowsy Signs you observe. Place him alone with toys (no screens, no sibling or parental interaction) for 1-15 minutes between 5:30-6-the #0pm for 2-3 nights and observe his mood and behavior and report back. Read Blog Post 196. I will help you.
Hi Dr. Weissbluth,
Thank you so much for your response. The drowsy signs we usually observe are him getting quiet/more still, tugging his ear, and red eyelids. After that comes eye rubbing and yawns if we’ve missed the sweet spot and are a little late to put him down. He still goes down easy and on his own, though.
I forgot to mention that we are working towards dropping his morning nap and just doing one long afternoon nap. Right now, since none of the other kids at his daycare take a morning nap, he naps in a pack-n-play outside while all the other kids are playing out in the yard. He has a sound machine, and is slightly away from the other kids, but it certainly isn’t a quiet environment or dark environment. I’m amazed he’s still been able to get that morning nap in at all, even if it is short.
We worked toward him just doing one nap this weekend and he napped great during the day (12:15-3ish) and then we put him down for bed around 7:30. He slept til after 6 both mornings! Thank goodness.
With this rough schedule, he’s getting about 13-14 hours of sleep in a 24 hour period. My concern though, is that he won’t nap for as long in the afternoon while at daycare. If he only gets one nap a day and it’s less than 2 hours, I really want to aim for him getting 12 hours at night.
When you say to place him alone with toys for 10-15 minutes between 5:30-6pm for a few nights and observe his behavior, do you mean in his crib to prepare for sleep, or do you just mean in a room alone with me watching him?
Thanks for the clarification and for helping us. I will read blog post 196 right now!
Watch him when alone with toys for 10-15 minutes between 5:30-6:30pm. I suspect that you will see some fatigue signs that have been masked by family activities. If so, I might suggest an earlier bedtime. Let’s see.
Hi Dr. Weissbluth,
Sorry it has taken me a while to respond. My family got sick, so it was hard to know if his interrupted sleep was due to his symptoms. But, he is feeling better now and we’re still dealing with 5am wake ups. I have tried observing him between 5:30-6:30pm without the distractions of family and I don’t see any obvious tired signs. He is usually happily playing and then crawls over to me to have me pick him up after a few minutes.
Here’s a snapshot of a few different days. Maybe you will be able to see a pattern that I’m not seeing.
– Woke up at 6:30am, nap 12-3:10, bed at 7:30 (no crying, easy to fall asleep), wake 6:15am, slept great all night
– Woke up at 6:15am, nap 12-2:30, bed at 7:15 (no crying, easy to fall asleep), woke up at 8:40pm for 10 minutes (didn’t go in and he fell back to sleep), we woke him up at 6:30am
– Woke up at 6:20, nap 12:15-1:50, bed at 6:40 (no crying, easy to fall asleep), woke up at 9:40 and cried for 25 minutes, slept the rest of the night, awake at 5:15am
– Woke up at 6am, nap 12:30-2:30, bed at 6:45 (no crying, easy to fall asleep), woke up at 9pm for 10 minutes, slept rest of night and woke up at 5:15am
– Woke up at 5:15, nap 12:30-2, bed at 6:55 (but cried til 7:10), woke up at 9:55pm and cried for 15 minutes, up at 5am
Perhaps the days where he doesn’t get a good nap (usually daycare days), are the ones when he just needs a super early bedtime?
Thanks so much for your help. We are motivated to figure this out so we can eventually move his older sister into the same room for them to share. But, right now she is on a mattress on our floor because we know her sleep will be interrupted by his early morning wake ups.
-Jess
“Perhaps the days where he doesn’t get a good nap (usually daycare days), are the ones when he just needs a super early bedtime?” Yes.
On days when there is no daycare, move the bedtime 20 minutes earlier for 3-4 consecutive days and observe latency to sleep onset and report back.