If School Started Later, Would Teenagers Just Stay Up Later?
Every August/September, families gear up to send their kids back to school, and sleep suddenly gets a lot less flexible.
Back to ....Alarms. Backup alarms. Buses. Sports practices. Homework and more homework.
And for a lot of older kids and teenagers, there simply aren't enough hours between when their bodies are ready to fall asleep and when they need to wake up for school.
This is one of the reasons school start times have become such a big topic in sleep medicine.
The American Academy of Pediatrics has recommended that middle and high schools start no earlier than 8:30 a.m. for more than a decade.
And every time this conversation comes up, someone asks a pretty reasonable question:
If school started later, wouldn't teenagers just stay up later?
Researchers have actually looked at this.
And, for the most part, the answer is no.
Teenagers really do sleep more when school starts later
Adolescence comes with a biological shift toward later sleep and wake times.
If you have a teenager who suddenly seems capable of staying awake long after the rest of the house is winding down and falling asleep, you've probably seen this firsthand.
They're not simply choosing a later bedtime (at least not always). Their internal clock is changing too.
That becomes a problem when a teenager whose body isn't ready for sleep particularly early needs to be awake at 6:00am or 6:30am to get ready for school.
There are really only so many places those extra hours of sleep can come from.
You can tell a teenager to go to bed earlier. You can put the phone away. You can have a good wind-down routine. All of those things may be useful.
But we can't completely override biology with a bedtime.
That's why school start times are so interesting.
When researchers look at what happens after schools move their start times later, students tend to wake later and get more sleep. They don't simply move their bedtimes later by the same amount.
A 2024 review looking across 37 studies found that later school start times were associated with longer sleep on weekdays and less “social jet lag”—the mismatch between the schedule someone's body gravitates toward and the schedule school or work requires.
The pandemic gave researchers an unexpected opportunity to see this play out in another way.
When school closures and remote learning removed early commutes and, in some cases, pushed morning schedules later, adolescents woke considerably later. Studies during that period found that many teenagers slept longer and more were able to get within the recommended range for sleep.
It was a pretty interesting natural experiment.
Give teenagers more opportunity to sleep in the morning, and many of them use it to sleep.
So what changes when teenagers get more sleep?
The most obvious thing is exactly what you'd expect.
They're less sleepy.
We talk a lot about children's sleep in terms of health, development, learning and behavior. But one of the clearest signs that a child simply isn't sleeping enough is excessive daytime sleepiness.
They're struggling to get out of bed.
They're falling asleep in the car.
They're relying heavily on caffeine.
They're fighting to stay awake in class.
They're sleeping dramatically later whenever they're finally given the opportunity.
Sometimes the explanation isn't particularly complicated.
They're tired because they're not getting enough sleep.
Research on later school starts has also found associations with better mood and some improvements in attendance and tardiness. Some individual studies have found academic benefits, although the research on grades and test scores is more mixed.
Parents often ask me about the impact of later school start times on grades. I try to answer as calmly as I can, but I want to yell:
We don't need to promise that starting school later will turn every teenager into a straight-A student to make a compelling case for adequate sleep.
Of course, changing school start times isn't simple
There's a reason every school in America hasn't just moved first period to 9:00 a.m.
Buses have to run. Parents have jobs with fixed start times. Sports happen after school. Teachers have families to get home to. Teenagers have jobs and extracurricular activities.
Districts sometimes use the same buses for elementary, middle and high school students, which means moving one schedule affects another.
Those are real problems. And I'm certain these examples only scratch the surface.
But the logistical difficulty doesn't change the biology.
An adolescent still needs adequate sleep whether the bus arrives at 6:45am or 8:15am.
And school start time is really only one piece of this anyway.
A teenager can attend a school with a perfectly reasonable start time and still not have enough time to sleep.
Which brings me to the question I think is more useful for most families.
Is there actually enough room in your child's day for sleep?
I would literally work backward.
What time does your child need to wake up?
Not what time does school start.
What time do they actually need to be awake?
If the bus comes at 7:05am, maybe they're up at 6:15am.
If they drive themselves, maybe it's 6:45am.
Then look at how much sleep your child needs and what time they would realistically need to be asleep to get it.
This can be surprisingly illuminating.
Sometimes the problem isn't that a teenager refuses to sleep, it's that the math doesn't work.
School ends at 3:00pm.
Practice until 6:00pm.
Home. Shower. Dinner. Homework.
Maybe there's an instrument, a club, a job, friends, family time or just a little time to sit on the couch and exist.
Suddenly we're asking a teenager to be asleep at 9:30pm so they can get enough sleep before a 6:00 a.m. alarm.
I also think we should talk about overscheduling
This is where the conversation gets bigger than sleep.
There are seasons when children are busy. A tournament runs late. There's a big paper due. Tech week happens. You travel. Life doesn't need to stop at 8:00 p.m. because sleep is important.
One short night is very different from a schedule that routinely leaves too little room for sleep.
If your child is regularly getting less sleep than they need, I'd look at the entire day before assuming you have a bedtime problem.
How much homework is there?
How many activities?
How late do practices run?
How much downtime does your child have?
When do they get to see their friends?
When do they get to see you?
And yes, how much time disappears into a phone or video games at night?
There may be several places to make changes.
There also may be seasons when you decide something is worth a later night.
I don't think we need to become so rigid about sleep that every late soccer game or sleepover feels like a health emergency.
Sleep can recover after an occasional short night. Giving your child an opportunity for additional sleep afterward is reasonable.
What I wouldn't recommend is treating the weekend as a permanent repayment plan for five chronically short school nights.
If your child routinely needs enormous amounts of catch-up sleep whenever school isn't forcing them awake, that's useful information about what's happening during the week.
What can you actually do if school starts too early?
Most parents reading this can't change Monday morning's bell schedule.
So start with what you can see.
Figure out the actual sleep opportunity. Work backward from the morning wake time and see whether there's realistically enough time available for sleep.
Protect the nights you can. Not every night will be perfect. If Tuesday runs late because of practice, maybe Wednesday doesn't need another commitment.
Look at the whole schedule. Sometimes reducing one evening activity or changing when homework happens makes more difference than another conversation about bedtime.
Keep mornings bright. Morning light is one of the strongest signals to the circadian system and can help anchor an earlier schedule.
Be thoughtful about weekends. Sleeping later after a short week can help with recovery. Huge swings between weekday and weekend schedules can also make Sunday night and Monday morning harder.
Don't overlook persistent sleepiness. A teenager who is getting an adequate opportunity to sleep and is still excessively sleepy deserves a closer look. Not all daytime sleepiness is simply sleep deprivation.
And if your child's school starts particularly early, it's reasonable to find out whether start times are already being discussed in your district.
California, where I live, became the first state to set statewide limits: public and charter middle schools generally can't begin before 8:00 a.m., and high schools generally can't begin before 8:30 a.m.
Of course, this doesn't make every teenager in California well-rested, but itrecognizes something sleep researchers have been saying for a long time:
When we talk about teenagers not getting enough sleep, we have to look at the schedule we're asking them to live on.
