Teenagers and sleep: why they go to bed at two and what it means

“At two in the morning the light under his door was still on. At half past six I couldn’t wake him. And when he came home from school in the afternoon, he fell asleep on the sofa with his jacket still on.”

This, or something very like it, is how many parents of teenagers describe their week. The evening drags on, the morning is a battle, and then comes the afternoon nap that stretches the next evening even further. A parent often swings between two explanations: either the child is lazy and stubborn, or something is seriously wrong. Most often it is neither. Much of what is happening is development — and part of it is a world that does not take that development into account.

In this piece I am writing mainly for you, the parent. I will look at what happens to the body clock during puberty, how much sleep a teenager really needs, what role the phone plays and what you can do at home without turning sleep into a new battleground. And finally, when going to sleep late is no longer just rhythm, but a sign that your teenager needs more help.

It isn’t laziness: the clock inside has moved

In the 1990s the sleep researcher Mary Carskadon and her colleagues noticed something that is now one of the most solid findings about adolescents: with puberty, the body clock shifts later into the night. It was not about age, but about the stage of puberty itself — children of the same age who were further into puberty preferred later evenings. Later research showed why: melatonin, the hormone that tells the body it is night, starts to be released later in teenagers than in younger children.

It is interesting to see when this shift ends. Till Roenneberg’s team, drawing on data from tens of thousands of people, found that on average we are at our most “owlish” around the age of twenty. After that the clock slowly begins to move back towards earlier hours. The authors even proposed this turning point as a biological marker of the end of adolescence.

For a parent, this means something simple and at the same time freeing: when your sixteen-year-old is not sleepy at ten in the evening, he is not defying you. At that hour his body is not yet sending him the signal to sleep. If you send him to bed, he will most likely lie there awake — and soon reach for his phone to make the waiting easier.

Two mechanisms that drift apart

Sleep is regulated by two systems. The first is the circadian rhythm, an inner clock that follows light and tells the body when it is day and when it is night. The second is sleep pressure: the longer you are awake, the more the need for sleep builds up, like sand in an hourglass.

In teenagers it is not only the clock that moves. Research shows that their sleep pressure also builds up more slowly during the day than in younger children. In the evening they can therefore stay awake more easily, without feeling it as an effort. Add to that everything else adolescence brings: more homework, training sessions that end late, a social life that mostly happens in the evening, and a screen that is always within reach. Researchers have called this combination nothing less than a “perfect storm”.

How much sleep a teenager really needs

In 2016 the American Academy of Sleep Medicine published an expert consensus on how much sleep children and adolescents need. For ages 13 to 18 they recommend 8 to 10 hours of sleep a night. Not seven, not “whatever you can get”, but eight to ten.

Compare that figure with the real week of most teenagers and the gap soon shows. If he falls asleep after midnight and has to get up at half past six, he will struggle to sleep more than six hours. Week after week a deficit builds up that one long Saturday lie-in cannot repay.

This is exactly why the American Academy of Pediatrics recommended back in 2014 that school for adolescents should not start before 8.30. In Slovenia there is hardly any public debate about this, but the question remains the same: we wake teenagers at half past six, at a time that is the middle of the night for their bodies, not because they are lazy, but because that is how the world around them is organised. As a parent, you cannot change that. What you can change is how you talk about it at home — and what you expect of him.

What happens when sleep runs short

Tiredness is only the most visible consequence in a teenager. The less visible ones often matter more.

• Mood. After too short a night, emotions are louder and willpower is weaker. What a rested teenager would shrug off brings a sleep-deprived one to tears or fury. I have written more about why in Sleep and emotion: why everything hurts more after a bad night.
• Attention and learning. Sleep is when the brain consolidates what it has learned. Someone who studies late into the night and then sleeps too little often remembers less than if they had gone to bed earlier.
• Relationships at home. The morning battle to get up, afternoon irritability, the evening row about the phone — a lot of the family tension we put down to “the teenage years” is partly the tension of a person who has not slept enough.
• Safety. For young drivers, cyclists and anyone who travels to school in the morning, sleepiness is a serious risk factor.

The reverse is also true: changes in sleep can be one of the first signs that something more is going on with a teenager. If at the same time you notice that he is withdrawing, losing interest in things he used to love, or has been low for a longer time, read Teenage depression: telling it apart from ordinary mood swings.

The phone: culprit or companion?

When parents talk about teenage sleep, the conversation almost always comes round to the phone. And not without reason: a review of research published in 2015 by Lauren Hale and Stanford Guan showed that in the great majority of studies, screen use in children and adolescents was linked to falling asleep later and sleeping less. This is especially true of screens in the bedroom and of use just before sleep.

But the phone is not the only culprit. A teenager whose body clock is keeping him awake would lie awake even without a phone — he would just stare at the ceiling. The phone fills the time when the body should be growing sleepy, and with content that excites or entertains, it pushes that sleepiness further away. The light from the screen is probably a smaller part of the story than is often thought; the bigger part is that on the other side there is a whole world that is not asleep.

That is why I do not recommend a war on the phone, but an agreement. How to put one together so that it is not just your order is explained in Teenagers and screens: how much is too much and where to draw the line, and you will find a ready template in the knowledge base as a family screen agreement. One rule has proved especially useful: the phone does not sleep in the bedroom at night. Not as a punishment, but like every other phone in the house — including yours.

Weekends and social jetlag

On Saturday the teenager sleeps until noon. The parent is annoyed that he is wasting the day, and the teenager feels as if he is finally rested. Both are partly right.

Roenneberg and colleagues coined the term social jetlag for the gap between when the body would sleep on its own and when school or work forces it to sleep — as if every week you flew across a few time zones and back. Long sleep at the weekend is partly a necessary repayment of debt. But at the same time it shifts the clock even later on Sunday evening, so Monday morning is even harder. A loop forms that does not stop by itself.

What helps is often the opposite of what we would intuitively do. Instead of pushing the teenager into bed an hour earlier in the evening, it makes more sense to work on the morning: light straight after getting up, breakfast, movement outdoors. Morning light is the strongest signal that pulls the clock back. At the weekend, let him sleep longer, but not without limit — a difference of up to two hours is usually much easier on the body than five or six.

How to talk about it without it becoming a row

A teenager often already has a bad conscience about his sleep — he hears it every morning. If a parent repeats at every opportunity that he does not sleep enough, he will mainly defend himself. A conversation that works better starts with curiosity rather than accusation. It might sound like this (a composite, not a real person):

“I notice you’re completely wiped out in the mornings. What’s it like when the alarm goes off?”
“Awful. But I really can’t fall asleep in the evening. It’s not that I don’t want to.”
“I believe you. I read that it’s completely normal at your age. What do you do when you can’t fall asleep?”
“I don’t know … watch something. Otherwise I just lie there and think.”
“What do you think about?”
“School. And everything.”

Two important things happened in this short conversation. The parent told the teenager that his experience is not a lie or an excuse. And she learned something she would never have learned by giving an order: that something is going round in his head in the evenings. From here on they can look together for what might help — instead of sleep becoming yet another area where the parent controls and the child lies.

Your own state counts too. A teenager still regulates himself alongside the adults he lives with, he just no longer shows it the way a small child does. We call this co-regulation. If the evening at home is calm, the lights are dimmed and your phone is put away too, it is much easier for him to settle as well. If late evening is when the house holds the most tension, sleep is harder for everyone.

Exercise: one week of observing, together

Before you change anything, it helps to know how things really are. This exercise is designed as something you do together, not as surveillance.

1. Suggest an experiment, not rules. You might say: “I’d like to understand why mornings are so hard. Would you track how we both sleep for a week?” If you want him to take part, take part yourself — keep your own record.
2. Each morning, write down three things: when the light went off, roughly when sleep came, and how rested you feel on a scale from 1 to 10. A simple sleep diary can help.
3. In the evening, add one line: what was the last thing he did before sleep, and whether anything was worrying him.
4. At the end of the week, sit down together and look at the notes without judging. Ask: “What do you see?” Often the teenager will notice a pattern himself that he would deny if you pointed it out.
5. Choose one single change for the following week — for instance the phone charging in the living room, or a walk before school. One, not five. After the week, review it together.

The exercise will not change biology. But it can change how you talk about sleep at home: from “you didn’t sleep again” to “let’s look at what is going on”.

When it isn’t just rhythm

Everything I have written applies to most teenagers. It does not apply to all of them, and here I want to be clear.

Falling asleep late is not the same as being unable to sleep. A teenager with a delayed rhythm falls asleep late, but then sleeps well, and if you let him, he sleeps for a long time. A teenager who lies awake for hours no matter when he goes to bed, who wakes in the night and cannot get back to sleep, or who is constantly exhausted despite long sleep, needs a check-up with the family doctor or paediatrician. For persistent insomnia there is an effective method without medication, which I wrote about in Cognitive behavioural therapy for insomnia (CBT-I). With adolescents it is provided by professionals who work with children and young people.

Sleep hygiene on its own is often not enough. A dark room, no caffeine or energy drinks, a regular schedule — all of this helps, but if anxiety, sadness or something the teenager does not talk about lies underneath the sleeplessness, rules will not solve it. More on this in What sleep hygiene is — and why on its own it often isn’t enough.

When distress lies behind the wakefulness. If a teenager cannot sleep at night because he is afraid, because someone is going after him at school or online, because he is self-harming or because he is thinking about death, this is not a question of rhythm. Then it is important not to leave him alone with it and to look for help: from the family doctor or paediatrician, the school counselling service, or a therapist who works with children and adolescents. A teenager can call the TOM helpline on 116 111 himself (in Slovenia). In a crisis there is also the mental health crisis line on 01 520 99 00 (from 7 pm to 7 am, in Slovenia) and the Samaritans helpline on 116 123 (24 hours a day, in Slovenia). When a life is in danger, call 112.

And when the whole family gets tangled up around sleep. Sometimes sleep is not a problem in itself, but the place where family tension shows — parents who disagree about the rules, a teenager who stays awake at night because there are arguments at home in the evening, or a parent who cannot sleep from worry. Then family therapy can help, where we do not look at one “problem” member, but at how the family moves together. I have described how such a conversation can open with a teenager who has gone silent at home in When a teenager goes quiet: how family therapy opens the conversation.

What you can do this week

A few small things that do not require big changes often turn out to be useful:

• Open the curtains in the morning and, if possible, let him walk or cycle part of the way to school.
• Keep the afternoon nap short and not late in the afternoon.
• Energy drinks and coffee after lunch rob most teenagers of more sleep than they think.
• Make the last hour before sleep calmer for you as well — shared quiet helps more than a lecture.
• Don’t expect miracles in a week. The body clock moves slowly, over days and weeks.

What to remember

• With puberty the body clock shifts later into the night — falling asleep late is biology first, not stubbornness.
• Teenagers need 8 to 10 hours of sleep; because school starts early, most get less.
• The phone is not the only culprit, but it fills the time when the body should be getting sleepy — an agreement works better than a ban.
• The rhythm is set less by an early bedtime than by morning light and a similar schedule every day.
• If a teenager cannot sleep no matter the hour, or there is distress behind the wakefulness, look for help — from a doctor, at school or from a professional who works with young people.