A Healthy Child Needs a Healthy Brain, A Healthy Brain Needs Healthy Sleep

This post is addressed to a specific reader: the parent who has not yet had her baby, or who has a baby who is days or weeks old. The parent for whom the sleep problem has not yet developed, because the habits that produce it have not yet been established.

Most of what I write is addressed to parents who are already in difficulty — who are up three and four times a night, whose child cannot fall asleep without nursing or rocking, who have a toddler with a bedtime that has drifted to nine or nine-thirty and a child who is struggling in ways the parent may not yet have connected to sleep. I write for those parents because they need help and the help is real and available.

But the most powerful moment to act is before any of that has happened.

If you are reading this before your baby arrives, or in the first days after, you are in the most advantageous position any parent can occupy: you have not yet started. What you do now will determine, more than almost anything else in your parenting life, whether sleep becomes a source of family health or a source of ongoing difficulty. The habits you establish in the first weeks are the habits your child will carry forward. The biology you work with now is the most plastic it will ever be.

Start as you mean to go.

What the first six weeks actually are

The first six weeks of life are biologically distinct from everything that follows. This is not a figure of speech. The newborn brain is not simply a small version of the three-month-old brain. It is a different neurological system, operating under different constraints, following a different set of rules.

The newborn has no consolidated circadian rhythm. The internal clock — the suprachiasmatic nucleus in the brain that will eventually govern the timing of sleep and wakefulness in a predictable daily pattern — is present but not yet entrained. The newborn does not know the difference between day and night in any biological sense. She sleeps in cycles of approximately fifty minutes, distributed across the full twenty-four hours, with no preference for nighttime. She wakes when she is hungry, which is frequently, because her stomach is small.

This is normal. This is not a sleep problem. This is the biology of the newborn period, and it cannot and should not be fought. The parent who expects a newborn to sleep through the night, or to follow a predictable schedule, or to consolidate sleep into long stretches, is expecting something the newborn brain is not yet capable of producing. This expectation produces frustration that is the parent’s problem, not the baby’s.

What the first six weeks require from parents is something much simpler than a sleep plan: respond to your baby’s needs, rest when she sleeps, and begin — gently, consistently, without urgency — to lay the foundations that will make healthy sleep possible when the biology is ready for it.

Colic: what it is and what it is not

Approximately one in five infants has colic — a pattern of inconsolable crying, typically in the late afternoon and evening, that begins in the first weeks of life, peaks around six weeks, and resolves by three to four months. Colic is among the most distressing experiences of early parenthood. A parent holding a screaming infant for hours every evening, unable to comfort her, exhausted and frightened and questioning her own competence, is in genuine distress. I do not minimize this.

What I want you to understand about colic is what it is not. Colic is not a medical problem. It is a sleeping/crying issue that is developmental. It will resolve. Not because of anything you do or stop doing. Because the biology matures.

The sleep problem that follows colic is not colic itself. It is what families inadvertently establish while managing colic — the motion, the nursing, the patting, the bouncing, the anything-that-works response to hours of inconsolable crying — and then continue after the colic has resolved because the habits are now encoded and the family does not know it is time to stop.

When the colic ends, at around two to four months, you are better able to encourage self-soothing. The plasticity of the biology at that moment is equivalent. The window is open. What you do in the weeks immediately following the resolution of colic is as consequential as what any family does at that age — possibly more so, because the colic period has likely produced some sleep associations that will need to be gently unwound. Do not carry the colic strategies of the colic period forward into the post-colic period. The colic is over. A new chapter has started. Begin it deliberately.

When colic winds down, encourage an early bedtime and promote more self-soothing for your baby.

Drowsy signs: learning to read the most important signal your baby sends

In the first weeks of life, your baby will communicate her readiness for sleep through observable signs. Learning to read these signs is among the most practically important skills you can develop as a new parent, because the window they represent is brief and catching it consistently is the foundation of everything that follows.

Drowsy signs are specific and distinct from fatigue signs, and the distinction matters.

Drowsy signs are the signals of a baby who is moving toward sleep from a calm-alert state: a slight softening of the gaze, a reduction in active engagement with the environment, a slowing of movement, a quality of stillness that is different from her ordinary wakefulness, a brief and gentle yawn. She is not yet fussy. She is not yet arching or pulling away from stimulation or difficult to console. She is in transition — the biology is moving toward sleep, and the conditions you provide at that moment will either support or interfere with that transition.

Fatigue signs are what comes next, if the drowsy period is missed: eye rubbing, ear pulling, increased fussiness that escalates toward crying, arching of the back, difficulty being consoled. These are not signs that your baby is getting ready for sleep. They are signs that your baby needed sleep fifteen minutes ago, that the biological window has passed, and that the cortisol rise that follows overtiredness — the second wind — is now making sleep harder to achieve rather than easier.

A baby put down during the drowsy period will fall asleep more easily than a baby put down in fatigue. This is not a minor difference in convenience. It is a difference in what the baby is learning about how sleep begins. A baby who falls asleep from calm drowsiness in consistent conditions is building the neurological association between those conditions and sleep onset. A baby who falls asleep from exhaustion, after extended crying or extended intervention, is building a different association — one that involves pre-sleep arousal, and often one that involves your active presence as a required condition.

Watch for the drowsy signs. Move when you see them. Do not wait.

When drowsy signs are difficult to detect (for example, in premature babies or when colic is present), focus on very brief intervals of wakefulness  between sleep periods.  For example, depending on the duration of a nap, your baby might want to return to sleep after only 30-90 minutes, always less than two hours.

Self-soothing: what it is and why it begins now

Self-soothing is the ability to transition from wakefulness to sleep, and from light sleep back to sleep during normal nighttime arousals, without requiring parental intervention. It is a skill. Like any skill, it is learned — and the learning begins not at four months, not at six months, but in the first days and weeks of life, every time you put your baby down and give her the opportunity to complete the transition to sleep on her own.

This does not mean leaving a newborn to cry. It does not mean withholding comfort from a baby who is genuinely hungry or genuinely distressed. It means noticing the difference between a newborn who is making the small, transitional sounds and movements of a baby settling into sleep and a newborn who is communicating real distress that requires your response. In the early weeks, you will spend a great deal of time learning to hear the difference. That learning is not wasted time. It is the foundation of your ability to support self-soothing as the months progress.

The concept of drowsy but awake is the most practical expression of this principle. When your baby is drowsy but still awake, place her in her sleep space. Not fully asleep — drowsy. Still conscious of the transition that is about to occur. Let her complete that transition in her sleep space, in the conditions you intend to be the consistent conditions of sleep onset. She may fuss briefly. She may make sounds. Watch, and give her a moment before you intervene. You are not abandoning her. You are giving her the first opportunity to practice the skill that will serve her — and you — for years.

If she cries, pick her up immediately, and return to soothing for sleep, but shorten the next  interval of wakefulness.

Every time you allow a drowsy baby to complete the transition to sleep without requiring your active intervention, you are doing two things simultaneously: you are letting her practice self-soothing, and you are not encoding your presence as a requirement for sleep onset. Both of these matter. They are not the same thing described twice. The presence you do not make required is the night waking you will not be called to resolve at two in the morning six weeks from now.

What you are building, and why the beginning matters most

Stimulus control is the encoded expectation that specific external conditions are required for sleep. It is not a behavior your baby chooses. It is a learned association, formed through repetition, between particular circumstances and the state of sleep. When a baby learns to fall asleep under specific conditions — being nursed, being rocked, being held, a parent lying beside her — those conditions become the requirements for sleep onset at every sleep onset, including the ones that occur during normal nighttime arousals when she moves through a light sleep phase and surfaces briefly.

This is why a baby who always falls deep asleep nursing might wake at two in the morning and require nursing to return to sleep. Not necessarily because she is hungry. Because the nursing is the encoded condition. Remove it and the transition cannot complete. She has not learned that the transition is possible without it, because she has never had the opportunity to discover that it is.  

The habits of the first weeks are not yet habits in the full sense — they are the raw material from which habits form. The associations being built now are more malleable than they will be at four months, and far more malleable than they will be at eight months. This is the gift of the newborn period: nothing is fixed yet. Everything is still being established.

Start as you mean to go is the principle I return to again and again with new parents, because it captures something that no other formulation quite does. It does not say: be rigid. It does not say: never comfort your baby. It says: be deliberate about what you are establishing, because what you establish in the beginning is what you will be working with — or working against — as the months unfold. If you mean to go toward a baby who can fall asleep in her sleep space, in consistent conditions, without requiring your active presence to complete the transition, then start toward that now. Gently, without urgency, with the full recognition that a newborn has needs that must be met and a nervous system that is still finding its footing. But start in that direction.

The evolutionary basis of early bedtimes

One of the most counterintuitive pieces of guidance I give new parents is this: the appropriate bedtime for a young infant is earlier than almost any parent expects. Not eight o’clock. Often six or six-thirty. Sometimes earlier.

This surprises parents because it does not match adult intuitions about what a reasonable bedtime looks like. It also produces a practical complication — a baby asleep at six-thirty means an evening that reorganizes itself around that fact. I understand the resistance.

Here is why the early bedtime around 6 weeks of age is not a parenting opinion. It is biology.

The human sleep system evolved across hundreds of thousands of years in environments without artificial light. The transition from wakefulness to sleep was governed by the fall of darkness, which in equatorial and temperate environments occurs in the early evening. The infant brain — far less modified by cultural adaptation than the adult brain — retains this evolutionary calibration with particular fidelity. The circadian system of the young infant is set early. The biological drive toward sleep onset rises in the late afternoon and early evening.

This is why the late bedtime that feels convenient for the family — nine, nine-thirty, later — produces the witching hour, the second wind, the baby who seemed exhausted at six and is inexplicably alert and impossible to settle at nine. She is running the biology she was born with, and the biology says: the window was earlier.

Work with this, not against it. In the first weeks, before the circadian rhythm has consolidated, bedtime will be variable and driven primarily by sleep pressure — by how long the baby has been awake and what her drowsy signs are telling you. As the night sleep rhythm develops around 6 weeks of age: Protect it. Move toward it. The early bedtime you establish in these weeks is not a constraint on family life. It is the foundation of a child who sleeps well, which is ultimately the foundation of a family that functions well.

What to do, starting now

The guidance for the first six weeks is not complicated. It is simple enough to hold in your mind during the fog of new parenthood, which is exactly what it needs to be.

Respond to your newborn’s needs without hesitation. She cannot be spoiled. She cannot manipulate you. She is a neurologically immature human being whose survival depends on the adults around her and whose nervous system is doing the most demanding developmental work it will ever do.

Begin, from the earliest days, to notice your baby’s drowsy signs. Watch for the softening, the quieting, the brief yawn. When you see them, move toward sleep — calmly, without rushing, but without waiting for the escalation that means the window has passed.

When your baby is drowsy, give her the opportunity to complete the transition to sleep in her sleep space. Not always. Not rigidly. But regularly enough that the beginning of the association between her sleep space and the experience of falling asleep is being established from the beginning.

Do not let the strategies of necessity become the habits of convenience. The bouncing and nursing and motion that get a newborn through a difficult moment are appropriate tools for the newborn period. They are not the architecture you want to build your child’s sleep on. Use them when you need them. Begin, gently and gradually, to step back from them as your baby shows the capacity to settle with less.

And start early. Earlier than you think is necessary. Earlier than feels intuitively right. The baby who is put to bed before pre-sleep arousal, before the escalation of overtiredness makes everything harder — that baby will teach you, quickly and convincingly, that the early bedtime was the right bedtime.

The sleep problem that brings most families to me has a history. It did not begin at the moment the parents recognized it. It began in the weeks and months before, in the small decisions made in the newborn period that seemed inconsequential at the time. The nursing to sleep that became the only way. The rocking that became required rather than optional. The bedtime that drifted later, a little at a time, until it was past where the biology needed it.

You are reading this before that history has been written. Write a different one.

— Marc Weissbluth, M.D.