Sleep at Every Age: A Complete Guide

James Wilson writes about children's and teenagers' sleep for SleepReview.

Sleep is one of those things we assume will just work — until it doesn't. And one of the most common questions I hear from parents, from patients, from anyone who's had a bad stretch of nights is: is this normal?

After a decade at Great Ormond Street Hospital, first as a registrars and then as a consultant in paediatric sleep medicine, and now working across the age spectrum, I can tell you that "normal" sleep is a moving target. What's healthy at two months would be alarming at two years. What's perfectly fine at fifteen would be pathological at forty-five. Sleep isn't a single thing — it's a system, and that system evolves continuously from the moment you're born until well into old age.

This guide is my attempt to map that system. Whether you're a new parent wondering why your three-week-old sleeps for two hours at a stretch, a teenager who can't fall asleep before midnight, a shift worker trying to sleep in daylight, or a grandparent whose sleep has quietly changed over the decades — this is for you. I'll walk you through what normal looks like at every age, what changes and why, and most importantly, when something might need attention.

Newborns (0–3 Months): The Fourth Trimester

If you've just had a baby and you're reading this while feeding at 3am for the fourth time tonight — first of all, I'm sorry. Second of all, what you're experiencing is completely, boringly, scientifically normal.

Newborns don't have a circadian rhythm. That internal body clock that tells the rest of us to sleep at night and wake in the morning? It doesn't exist yet at birth. It takes roughly six to eight weeks for the infant brain to begin producing melatonin in a day-night pattern, and even then, it's rudimentary. Your newborn is, in a very real sense, jet-lagged from the moment they arrive — and they're going to stay that way for a while.

What normal looks like:

• Total sleep: 14–17 hours per 24-hour period
• Sleep is distributed across the day and night in roughly equal amounts
• Sleep cycles last about 50–60 minutes (compared to 90 minutes in adults)
• Night-time stretches of 2–4 hours between feeds are typical
• The longest stretch may occur during the day — not at night

The key insight for new parents is this: your baby isn't sleeping "badly" — they're sleeping exactly as their brain is wired to sleep at this stage. The scattered sleep pattern is an evolutionary safeguard. In our distant past, an infant who slept solidly for eight hours would have been vulnerable. Frequent waking ensured regular feeding and kept the baby close to the caregiver.

There is no sleep training to be done in this period, and I would urge caution against anyone who tells you otherwise. What you can do is begin to introduce very gentle cues that will help the circadian rhythm develop: bright natural light during daytime feeds, a dimmer environment at night, and keeping night-time interactions boring and minimal. These aren't sleep training — they're environmental signals that gently nudge the developing brain toward day-night differentiation.

The thing I most want new parents to hear is this: this phase is temporary. It feels eternal at 3am on a Tuesday, but most babies begin to consolidate their sleep into longer night-time stretches between three and six months. Not because of anything you did or didn't do — because their brain matured. Be patient with the process. Be patient with yourself.

Babies (3–12 Months): Finding a Pattern

Between three and six months, something remarkable happens. The circadian rhythm switches on. Your baby starts producing melatonin at night and cortisol in the morning, and suddenly — sometimes overnight, sometimes over a few weeks — night-time sleep stretches out. This is the window where many parents see their first five- or six-hour stretch, and it feels like a miracle.

What normal looks like:

• Total sleep: 12–16 hours (including naps)
• Night-time stretches of 6–8 hours by six months (some babies earlier, some later)
• Two to three naps per day, reducing to one nap by around 12–15 months
• Night-time sleep is now the dominant block

By six months, most paediatric sleep specialists — myself included — consider sleep training a reasonable option for families who want it. I want to be clear about what I mean by that: sleep training is not one thing. It exists on a spectrum from graduated extinction (the "controlled crying" approach) to the camping-out method where you gradually move your chair further from the cot each night.

There is no single "right" method. The right method is the one that works for your family and that you can sustain consistently.

The evidence is robust: sleep training, when done with a baby who is developmentally ready, is safe, effective, and does not cause long-term harm. A landmark 2016 study in Pediatrics followed sleep-trained children for five years and found no adverse effects on emotional health, stress regulation, or the parent-child relationship. That doesn't mean every family should sleep train — it's a personal choice. But if you're considering it, you can do so without guilt.

At this stage, nap transitions are the other big milestone. Most babies drop from three naps to two between five and seven months, and from two to one between twelve and eighteen months. These transitions are messy. Your baby will resist, they'll be overtired, and you'll question everything. It passes. The key is to watch your baby's sleepy cues rather than the clock — if they're fighting the third nap, they're probably ready to drop it.

One piece of practical advice I give every parent at this stage: keep a sleep log for two weeks. Write down when your baby sleeps, for how long, and how they seem (content, cranky, fighting sleep). Patterns emerge quickly, and patterns are the foundation of a workable schedule. You can't fix what you can't see.

Toddlers (1–3 Years): The Battle for Bedtime

I'll be honest — toddlers are my favourite age group to talk about, because the sleep challenges at this stage are so achingly predictable, so universal, and so maddening for parents. If you have a toddler, you've probably experienced the "one more wee," the sudden desperate need for a specific toy that's downstairs, or the classic "I'm not tired" declaration delivered while literally falling asleep standing up.

What normal looks like:

• Total sleep: 11–14 hours in 24 hours (including one nap)
• One nap, typically 1–2 hours, usually in the early afternoon
• Night-time sleep of 10–12 hours
• Bedtime resistance is normal — falling asleep within 20–30 minutes of lights out is fine

The primary sleep challenge at this age is separation anxiety, which peaks around two to three years. Your toddler's cognitive development has advanced to the point where they understand that you exist independently of them — and that you can leave. But they haven't yet fully grasped that you're coming back. This is genuinely distressing for them, and it drives a lot of bedtime battles.

The solution, such as it is, involves consistency and a brief, repeatable goodbye ritual. The same steps every night, in the same order, with the same words. Not a negotiation. Not a new story. Not a different goodnight song. The sameness is the point — it becomes a signal to the brain that sleep is next, and it provides the reassurance of predictability.

The nap is the other major consideration. Drop it too early, and your toddler becomes overtired and harder to settle at night. Keep it too late, and it eats into night-time sleep. Most children are ready to drop the nap between three and five, but the transition is gradual — some days they'll nap, some days they won't, and that's fine. What I recommend is keeping the nap opportunity (quiet time in a dark room) until age four, and if they sleep, they sleep.

One more thing about this age: the "big bed" transition is a common trigger for sleep regression. Moving from a cot to a bed gives a toddler freedom they've never had before — they can get out. This is thrilling and terrifying in equal measure.

If possible, delay the transition until your child is three or older and has the self-control to stay in bed. When you do make the move, put a stair gate at the bedroom door so they can see you and feel safe, but can't roam the house.

Related reading: For a deeper dive into toddler and older children's sleep challenges, see our guide on children's sleep problems.

Children (4–12 Years): When Sleep Gets Complicated

The preschool and primary school years are often viewed as the "easy" phase of children's sleep, and in many ways they are — your child can sleep independently, follow a routine, and articulate what's bothering them. But this is also the age where a new category of sleep disruptors emerges: worry, school pressure, social dynamics, and screens.

What normal looks like:

• Ages 3–5: 10–13 hours (some still nap occasionally)
• Ages 6–12: 9–12 hours
• Bedtime typically between 7:30pm and 9:00pm depending on age and wake time
• Most children fall asleep within 15–30 minutes

The most common sleep disruptor in school-age children isn't physical — it's cognitive. This is the age when children begin to develop genuine anxiety. They worry about school tests, friendship dynamics, whether they'll get picked for the team, whether Mum and Dad will split up, whether a burglar will come. These worries don't vanish at bedtime — they intensify, because darkness and quiet remove all the distractions that keep them at bay during the day.

The approach I recommend is what I call the "worry download" — a brief bedtime conversation where your child names one thing they're worried about and one thing they're happy about. It takes two minutes. It externalises the worry, makes it tangible, and gives you a window into their inner world. If the worry is substantial — a bullying situation, a family change — address it properly. If it's small, acknowledge it and move on. The act of naming it is what matters.

Screens are the other major factor at this age, and the research is unambiguous: screen exposure in the hour before bedtime impairs sleep onset and reduces sleep quality. Blue light from screens suppresses melatonin production, but more importantly, the stimulation of games, videos, and social media activates the brain in ways that are incompatible with the wind-down process. A child watching YouTube at 8pm when bedtime is 8:30pm is essentially giving their brain a "stay awake" signal.

What actually works: screen-free from one hour before bedtime. Not "screen time is limited" — screen-free. The distinction matters because a child on a tablet for 20 minutes before bed still gets the melatonin suppression and the stimulation. It's not about duration; it's about proximity to sleep. And this rule applies to parents too — the hypocrisy of scrolling your phone while telling your child screens are off is not lost on children.

The other thing that changes in this age range is the consequences of sleep deprivation shift. A tired toddler falls asleep on the floor. A tired ten-year-old becomes irritable, struggles to concentrate, and may be labelled as having behavioural problems. Many children I see at Great Ormond Street who had been referred for ADHD or conduct disorder were, in fact, chronically sleep-deprived. Addressing the sleep problem resolved the daytime symptoms. Always check sleep first.

Teenagers (13–17 Years): Fighting Biology

If you have a teenager, you've probably said — or thought — "they're just lazy" about their sleep patterns. I understand why. It looks like laziness. They refuse to get up in the morning, they're wired at night, and they want to sleep until midday on weekends. But I need you to hear this: it's not laziness. It's biology.

During puberty, the circadian rhythm shifts forward by approximately two to three hours. This is called sleep phase delay, and it's driven by hormonal changes — specifically, a later onset of melatonin secretion in the evening. A teenager's brain genuinely doesn't start producing melatonin until around 11pm or later, compared to 9pm or earlier for adults and younger children. Forcing a fifteen-year-old to fall asleep at 9:30pm is like forcing an adult to fall asleep at 6:30pm — their biology simply isn't ready.

What normal looks like:

• 8–10 hours of sleep per 24 hours
• Natural sleep onset: 11pm–1am
• Natural wake time: 8am–10am
• A need for later sleep and later waking that conflicts with school schedules

This creates a genuine societal problem. Schools start early. Teenagers biologically sleep late. The result is chronic sleep deprivation, and the consequences are severe: impaired academic performance, increased risk of depression and anxiety, reduced impulse control, higher rates of road accidents, and weakened immune function. This isn't a personal failing — it's a structural mismatch between biology and the education system.

What can you do? A few things that actually help:

• Protect weekend sleep. Allowing a teenager to sleep in on weekends partially repays their sleep debt. This isn't indulgent — it's medically sensible. The ideal is no more than one to two hours later than their weekday wake time, but any extra sleep helps.
• Enforce a screen curfew. Blue light at 10pm delays melatonin by a further one to two hours, making the already-delayed sleep onset even later. Screens off by 9:30pm is a reasonable compromise — they can read, listen to music, or talk, they just can't be staring at a backlit screen.
• Morning light exposure. Bright light in the morning — ideally natural sunlight — helps set the circadian clock earlier. Encourage your teenager to get outside briefly after waking, or at least open the curtains.
• Caffeine awareness. Many teenagers consume significant caffeine through energy drinks and coffee. Caffeine has a half-life of five to six hours, meaning a can of Monster at 4pm still has half its caffeine active at 10pm.

The most important thing I tell parents of teenagers is this: picking the right battle matters. If your teenager is getting 8–9 hours most nights, has reasonable screen habits, and is functioning well at school — don't fight about the exact bedtime. Their body clock is working against you, and rigid rules can damage the relationship without improving the sleep.

Save your energy for the battles that matter: eliminating screens in the bedroom, limiting caffeine, and ensuring they're not chronically under-sleeping by four or more hours.

Related reading: For a detailed look at how many hours each age group actually needs, see How Many Hours of Sleep Do I Need?

Adults (18–64 Years): The Silent Epidemic

Here's something that surprises many people: adult sleep has changed more in the last century than at any other point in human history. The average adult in 1900 slept approximately eight hours per night. The average in 2026 is closer to six hours and forty minutes. We're sleeping less than any previous generation, and the health consequences are enormous.

What normal looks like:

• 7–9 hours per night for adults aged 18–64
• Sleep efficiency (time asleep vs time in bed) of 85% or higher is healthy
• Falling asleep within 10–20 minutes of lights out
• Waking once briefly during the night is normal

The primary enemies of adult sleep are stress, irregular schedules, and light exposure. Stress keeps the sympathetic nervous system activated, flooding the body with cortisol and adrenaline — chemicals that evolved to keep us alive in genuine danger, not to help us fall asleep after an argument about the mortgage.

An irregular schedule — going to bed at different times on different nights — disrupts the circadian rhythm, which functions best with consistency. And evening light exposure, from screens, overhead lighting, and even streetlights, suppresses melatonin and delays sleep onset.

The evidence-based interventions that work are unglamorous but effective:

• Consistent sleep-wake times. Within a 30-minute window, seven days a week. Yes, weekends too. This is the single most powerful thing you can do for your sleep.
• Bedroom environment. Cool (16–18°C), dark (blackout curtains or a good eye mask), quiet (earplugs or a white noise machine if needed). Your bedroom should be a sleep cave, not a second office.
• No screens in bed. Your bed is for sleep and intimacy. Nothing else. Train your brain to associate the bed with sleep, not with scrolling.
• Wind-down routine. 30–60 minutes of reduced stimulation before bed — dim lights, no email, no news, no arguments. Read a book, have a bath, listen to music. It's not about doing something special; it's about not doing stimulating things.

I want to address something that comes up constantly: the culture of sleep deprivation as a badge of honour. "I only need five hours." "Sleep is for the weak." "I'll sleep when I'm dead." These attitudes are not just wrong — they're dangerous.

Chronic sleep deprivation is associated with increased risk of cardiovascular disease, type 2 diabetes, obesity, depression, impaired immune function, and cognitive decline. It's as harmful as smoking in terms of long-term health impact. Sleep is not a luxury. It's a biological necessity.

Related reading: For a deeper exploration of why you might be tired all the time, see Why Am I Tired All the Time? and for a comprehensive overview of sleep hygiene practices, see our Complete Guide to Sleep Hygiene.

Sleep as a New Parent: Surviving the First Year

If you're a new parent, you already know that your sleep has changed. What you might not know is how it's changed, because it's not just about having a baby who wakes up. It's about your brain fundamentally rewiring itself.

Research from the University of Warwick found that parents experience significant changes in their sleep architecture during the first year after a baby's birth. Both mothers and fathers show reduced sleep efficiency, increased nighttime awakenings, and more fragmented sleep — even when the baby is sleeping through. This is because the parental brain develops a heightened state of vigilance; it becomes exquisitely tuned to the baby's sounds, and it resists deep sleep as a protective mechanism.

What normal looks like (for you, not the baby):

• Multiple nighttime awakenings, even as the baby sleeps longer stretches
• Difficulty falling back asleep after feeds or settling
• Feeling "tired but wired" — exhausted but unable to sleep deeply
• Variable sleep quality that tracks with the baby's developmental leaps

The strategy that I recommend to every new parent is sleep banking and shift sleeping. Before the baby arrives, sleep as much as possible — not because you can stockpile sleep, but because you can stockpile the energy reserves that sleep provides. After the baby arrives, if you have a partner, split the night into shifts.

One parent covers 8pm to 1am, the other covers 1am to 6am. During your shift, you're "on duty" — the other parent sleeps with earplugs and a white noise machine. This ensures each parent gets one solid four-to-five-hour block, which is the minimum needed to function.

And please, don't feel guilty about co-sleeping safety discussions without understanding the full picture. The NHS guidelines are clear: the safest place for a baby to sleep is on their back, in a separate cot or Moses basket, in the same room as the parent, for at least the first six months.

Room-sharing (same room, separate sleep surface) reduces the risk of SIDS by up to 50%. Bed-sharing carries increased risk, particularly if a parent is extremely tired, has consumed alcohol, or is on certain medications. The advice is not about judgement — it's about minimising risk during a period when everyone is exhausted.

Most importantly: this phase ends. I know it doesn't feel like it at 3am when you've been awake for the fifth time. But the research shows that parental sleep quality largely normalises by the child's second birthday. In the meantime, accept help, lower your standards for everything that isn't keeping the baby alive and safe, and remember that you're doing something incredibly difficult and you're doing it well enough.

Related reading: For a practical survival guide to the newborn period, see New Parent Sleep Survival Guide.

Shift Workers: Sleeping When the World Is Awake

I want to talk directly to shift workers for a moment, because your sleep challenges are unique, serious, and systematically under-acknowledged. Roughly 15–20% of the UK workforce works shifts, including nights. These are the people who keep our hospitals running, our power stations operational, our emergency services staffed. And they're doing it on a sleep schedule that their biology is fundamentally hostile to.

What normal looks like for shift workers:

• Daytime sleep that is shorter and more fragmented than night-time sleep
• Difficulty falling asleep in daylight despite exhaustion
• Rotating shifts that prevent the body clock from ever fully adjusting
• Chronic sleep debt that accumulates over weeks and months

The core problem is that the human circadian rhythm is entrained to light-dark cycles, and no amount of blackout curtains fully overrides millions of years of evolutionary programming that says "light means day, dark means night." Shift workers who work permanent night shifts can partially adapt, but even they rarely achieve full circadian inversion. Rotating shift workers — who alternate between days, evenings, and nights — never adapt, because by the time their body clock adjusts, the schedule changes again.

What actually helps:

• Strategic light exposure. Bright light during the first half of your shift (to promote alertness), and sunglasses or dim lighting during your commute home (to prevent suppressing melatonin). This is the single most evidence-based intervention for shift workers.
• Sleep environment. Blackout curtains are non-negotiable. Combine with an eye mask for redundancy. White noise machines mask daytime traffic and household sounds. A cool bedroom temperature (16–18°C) promotes sleep onset.
• Consistent sleep schedule on days off. This is the hardest one. The temptation is to revert to a "normal" schedule on days off, but this essentially gives you jet lag every time you switch. Keeping a consistent schedule — even on days off — improves overall sleep quality, though it can feel socially isolating.
• Caffeine timing. Caffeine is a legitimate tool for shift workers, but timing matters. Use it at the start of your shift, not the end. Avoid caffeine in the four hours before you plan to sleep.
• Napping. A 20-minute "power nap" before or during a night shift can significantly reduce fatigue. A longer nap (90 minutes, covering a full sleep cycle) can be used to supplement night-time sleep if needed.

I also want to be honest about something: shift work carries inherent health risks that cannot be fully mitigated. Shift workers have higher rates of cardiovascular disease, metabolic disorders, gastrointestinal problems, and certain cancers. The World Health Organization classifies night shift work as a probable carcinogen. This is not meant to alarm you — it's meant to validate that what you're doing is hard, it takes a physical toll, and you deserve support, better scheduling practices, and regular health monitoring.

Related reading: Our comprehensive guide at How to Sleep When You Work Night Shifts covers shift work sleep strategies in much greater detail.

Seniors (65+): The Myth of Bad Sleep

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