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When Should Schools Start in the morning?

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This is not really a new post. But it is not exactly a re-publishing of an old post either. It is a lightly edited mashup or compilation of excerpts from several old posts – I hope it all makes sense this way, all in one place. The sources of material are these old posts:

Sleep Schedules in Adolescents (March 26, 2006)
ClockNews – Adolescent Sleep (March 28, 2006)
More on sleep in adolescents (April 01, 2006)
When Should Schools Start in the morning? (April 02, 2006)
All Politics Is Local (June 29, 2006)
Adolescent Sleep Schedule (September 10, 2006)
Books: “Snooze…Or Lose! – 10 “No-War” Ways To Improve Your Teen’s Sleep Habits” by Helene A. Emsellem, MD (May 15, 2008)


I am glad to see that there is more and more interest in and awareness of sleep research. Just watch Sanjay Gupta on CNN or listen to the recent segment on Weekend America on NPR.

At the same time, I am often alarmed at the levels of ignorance still rampant in the general population, and even more the negative social connotations of sleep as an indicator of laziness.

Nothing pains me more than when I see educators (in comments) revealing such biases in regards to their student in the adolescent years. Why do teachers think that their charges are lazy, irresponsible bums, and persist in such belief even when confronted with clear scientific data demonstrating that sleep phase in adolescents is markedly delayed in comparison to younger and older people?

In short, presumably under the influence of the sudden surge of sex steroid hormones (and my own research gently touched on this), the circadian clock phase-advances in teen years. It persists in this state until one is almost 30 years old. After that, it settles into its adult pattern. Of course, we are talking about human populations, not individuals – you can surely give me an anecdote about someone who does not follow this pattern. That’s fine. Of course there are exceptions, as there is vast genetic (and thus phenotypic) variation in human populations. This does not in any way diminish the findings of population studies.

Everyone, from little children, through teens and young adults to elderly, belongs to one of the ‘chronotypes’. You can be a more or less extreme lark (phase-advanced, tend to wake up and fall asleep early), a more or less extreme owl (phase-delayed, tend to wake up and fall asleep late). You can be something in between – some kind of “median” (I don’t want to call this normal, because the whole spectrum is normal) chronotype.

Along a different continuum, one can be very rigid (usually the extreme larks find it really difficult to adjust to work schedules that do not fit their clocks), or quite flexible (people who find it easy to work night-shifts or rotating shifts and tend to remain in such jobs long after their colleagues with less flexible clocks have quit).

No matter where you are on these continua, once you hit puberty your clock will phase-delay. If you were an owl to begin with, you will become a more extreme owl for about a dozen years. If you are an extreme lark, you’ll be a less extreme lark. In the late 20s, your clock will gradually go back to your baseline chronotype and retain it for the rest of your life.

The important thing to remember is that chronotypes are not social constructs (although work-hours and school-hours are). No amount of bribing or threatening can make an adolescent fall asleep early. Don’t blame video games or TV. Even if you take all of these away (and you should that late at night, and replace them with books) and switch off the lights, the poor teen will toss and turn and not fall asleep until midnight or later, thus getting only about 4-6 hours of sleep until it is time to get up and go to school again.

More and more school districts around the country, especially in more enlightened and progressive areas, are heeding the science and making a rational decision to follow the science and adjust the school-start times accordingly. Instead of forcing teenagers to wake up at their biological midnight (circa 6am) to go to school, where invariably they sleep through the first two morning classes, more and more schools are adopting the reverse busing schedule: elementary schools first (around 7:50am), middle schools next (around 8:20am) and high schools last (around 8:50am). I hope all schools around the country eventually adopt this schedule and quit torturing the teens and then blaming the teens for sleeping in class and making bad grades.

No matter how much you may wish to think that everything in human behavior originates in culture, biology will trump you every now and then, and then you should better pay attention, especially if the life, health, happiness and educational quality of other people depends on your decisions.


Recently, Lance Mannion wrote an interesting post on the topic, which reminded me also of an older post by Ezra Klein in which the commenters voiced all the usual arguments heard in this debate.

There are a couple of more details that I have not touched upon in the previous posts.

First, lack of sleep can lead to obesity and even diabetes, as the circadian clock is tightly connected to the ghrelin/leptin system of hormonal control of hunger, feeding and fat-deposition.

Second, lack of sleep discourages exercise. Put these two pieces of data together, and you get a national epidemic of obesity, not just a bunch of sleep-deprived children.

Third, lack of sleep has a well-documented effect on mood. No, teenagers are not naturally that moody – at least not all of them. They are just barely “functional” (instead of “optimal”) and walk through life like zombies because they are operating on 4-8 hours of sleep instead of 9 hours (optimal for teens, it goes down to about 8 for adults). Of course they are moody.

Fourth, chronic sleep deprivation can have long-term consequences, ranging from psychiatric diseases to cancer. Remember that teens in high-school (and college students are faring worse!) are constantly jet-lagged!

There is even a hypothesis floating around that sleep-delay in adolescence may affect the onset of picking up smoking.

Fifth – and I did not think of this although it is obvious – teenagers above a certain age, still in high school, are allowed to drive. If they are driving themselves to school at 6 or 7am, when their circadian clocks think is it 3 or 4am, it is as if they are driving drunk. There is actually a scale devised by one of the sleep researchers that tells which time of the night corresponds to what number of bottles of beer. Driving at 4am (or driving a ship, like Exxon Valdez, or operating a power-plant, like one in Chernobyl) is the equivalent of driving drunk – way over the legal limits. Teenagers driving at 7am are equally “drunk”.

One of the reasons for the resistance to healthy initiatives to change school-start schedules stems from the fact that the world is organized by adults and adults want to have the world run according to schedules that fit their moods and are unwilling to change it – they may not know that teens feel differently, or they defend their preferences nonetheless.

A large proportion of adults in this country still subscribe to barbaric notions that sleep is a shameful activity, a sign of laziness, and that teens need to be tortured in order to “steel” them to grow into “real men”. This has roots all the way back to the Puritan so-called “work-ethic” which is really a “no fun for anyone” punitive ethic long ago shown to be physically and emotionally debilitating.

When I was a kid, back in old now-non-existent Yugoslavia, most schools in big urban areas worked in two shifts. All the kids started school at 8am and ended at 1:15pm for one week, then started at 2pm and ended at 7:15pm the next week, and so on…

If a school had, let’s say, twelve classes of the seventh grade, six of those would be in the A-shift and the other six in the B-shift. Each shift had its own complete set of teachers, assistants, nurses…everything except the one shared Principal and the school psychologist.

The time between 1:15pm and 2pm was for supplementary classes (either for those who needed extra help, or for those preparing for Math Olympics and such) and clubs. That was also time for kids from two shifts to meet and get to know each other (it is amazing how many kids from opposite shifts started dating each other after the year-end Big Trip to the Coast). There was no such thing as the American hype for high-school competitive sports, which I still find strange and curious after 15 [now 20] years in this country.

Thus, you get to sleep in for a week (but miss out on afternoon activities), then have to get up relatively early for a week but have the afternoon free to gallivant around town. Nobody there understands what’s the American fuss over kids being home alone – of course they are home alone, cleaning the house, fixing meals, doing homework and BETTER be getting to school on time!

Teachers were pretty understanding about sleeping types. I do not recall ever having a big test, quiz or exam being given at the extremes of the day (around 8am or around 7pm). As an owl myself, I was much more likely to raise my hand, participate in discussions, or volunteer for oral examinations during the week when I was in school in the afternoon, and that was fine with most of my teachers.

Transportation was not an issue. Most kids lived close enough to their neighborhood school to walk. For those who lived a little farther away – hey, no problem, that’s Europe, so Belgrade has a huge and pretty efficient public transportation system. I do not remember ever seeing any of my friends ever being dropped off to school by a parent driving a car! Or being brought to or picked up from school by a parent beyond fourth grade at all – period. And the minimum driving age being 18, nobody drove themselves to school either.

In rural areas, there was no need for two shifts – something like 9am-2:15pm was good enough to accommodate all of the kids.

I do not think that this kind of system can be implemented in the USA. It relies on an efficient public transportation which, with exception of a few oldest East Coast cities, is practically non-existent. American cities have been built for cars.

But some things can be done.

First, swap the starting times so elementary kids go to school first, middle school next and high school last (e.g., around 8am, 8:30am and 9am respectively). Studies show that teens do not go to sleep later if their school starts later. Some cynics claim that is what teens will do. But they do not. Actually, they fall asleep at the same time, thus gaining an additional hour of sleep.

Teens are almost adults. The current generation of teens, perhaps because of a closer and tighter contact with their parents than any generation before, is the most serious, mature and responsible generation I have seen. Give them a benefit of the doubt. Just because you were into mischief and hated your parents when you were their age does not mean that today’s kids are the same.

Second, start the school day – for all kids every day – with PE (or some kind of exercise), preferably outdoors, as both exposure to daylight and the exercise have been shown to aid in phase-shifting the circadian clock.

Third, let them eat breakfast afterwards (sticking to a meal schedule also helps entrain the clock). Follow up with the electives which kids may be most interested in.

By the time they hit math, science and English classes around 11 or so, their bodies are finally fully awake and they can understand what the teacher is saying, and do the tests with a clear mind instead of in a sleepy haze.

Do not permit any caffeine to be sold in schools. Advise parents not to allow TV or any other electronics to be in kids’ bedrooms. Let them enjoy those activities in the living room. Bedroom is for sleeping, and sleeping alone. A book before bed is fine, but screens just keep them awake even longer.

Finally, rethink all those extra activities you are forcing the teens to do: sports, art, music, etc. In teen’s minds, the day does not start with the beginning of school in the morning. We may think that we are at work most of our day. Teens do not – they consider their day to begin at the time school-day is over. Their day begins in the afternoon. School is something they have to deal with before they can have their day. Realize this and give them time and space to do with their day what they want. Do not push them to do things that you think they’ll need to get into Harvard. Let them be – leave them alone. Then they’ll go to sleep at a normal time.

Concern for our kids’ physical and mental health HAS to trump all other concerns, including economic costs, cultural traditions and adult preferences. We have a problem and we need to do something, informed by science, to fix the problem. Blaming the messenger, proposing to do nothing, and, the worst, blaming the kids, is unacceptable.


All of this targets high-schoolers. However, there is barely any mention of college students who are, chronobiologically, in the same age-group as high-school students, i.e., their sleep cycles are phase-delayed compared to both little kids and to adults.

In a way, this may be because there is not much adults can do about college students. They are supposedly adults themselves and capable of taking care of themselves. Nobody forces (at least in theory) them to take 8am classes. Nobody forces them to spend nights partying either.

They are on their own, away from their parents’ direct supervision, so nobody can tell them to remove TVs and electronic games out of their bedrooms. The college administrators cannot deal with this because it is an invasion of students’ privacy.

Forward-looking school systems in reality-based communities around the country have, over the last several years, implemented a policy that is based on science – sending elementary school kids to school first in the morning, middle-schoolers next, and high-schoolers last. This is based on the effects of puberty on the performance of the human circadian clock.

For teenagers, 6am is practically midnight – their bodies have barely begun to sleep. Although there have been some irrational (or on-the-surface-economics-based) voices of opposition – based on outdated notions of laziness – they were not reasonable enough, especially not in comparison to the scientific and medical information at hand, for school boards to reject these changes.

I am very happy that my kids are going to school in such an enlightened environment, and I am also happy to note that every year more school systems adopt the reasonable starting schedules based on current scientific knowledge.

Yet, college students are, from what I heard, in much worse shape than high-schoolers. Both groups should sleep around 9 hours per day (adults over thirty are good with about 8 hours). High-schoolers get on average 6.9 hours. College students are down to about five! The continuous insomnia of college students even has its own name in chronobiology: Student Lag (like jet-lag without travelling to cool places). Is there anything we, as a society, can do to alleviate student lag? Should we?


This kind of ignorant bleating makes me froth at the mouth every time – I guess it is because this is my own blogging “turf”.

One of the recurring themes of my blog is the disdain I have for people who equate sleep with laziness out of their Puritan core of understanding of the world, their “work ethic” which is a smokescreen for power-play, their vicious disrespect for everyone who is not like them, and the nasty feeling of superiority they have towards the teenagers just because they are older, bigger, stronger and more powerful than the kids. Not to forget the idiotic notions that kids need to be “hardened”, or that, just because they managed to survive some hardships when they were teens, all the future generations have to be sentenced to the same types of hardships, just to make it even. This is bullying behavior, and disregarding and/or twisting science in the search for personal triumphalism irks me to no end.

I hated getting up early, too. I still hate it, and I’m so far beyond growth hormones that I don’t even remember how they felt. But I do remember that in middle and high school, I dragged myself out of the house at 5 a.m. every day of the week to deliver papers before I caught the 6:45 a.m. bus to school. I never fell asleep in class. Neither did anybody else. And something caused me to grow 6 inches and add 35 pounds between sophomore and junior year. At the end of that kind of day, complete with cross-country, basketball or track, I had no trouble falling asleep at 10 p.m.

He said that he grew up in height and weight when he was in high school. Who knows how much more he would have grown if he was not so sleep deprived (if his self-congatulatory stories are to be believed and he did not slack off every chance he had). Perhaps he would not grow up to be so grouchy and mean-spirited if he had a more normal adolescence.

I don’t know where he got the idea that growth hormone is a cause of the phase-delay of circadian rhythms in adolescence. It could be, but it is unlikely – we just don’t know yet. But, if a hormone is a cause, than it is much more likely to be sex steroids. Perhaps his sleep-deprived and testosterone-deprived youth turned him into a sissy with male anxiety he channels into lashing at those weaker than him?

In previous centuries, adolescents in an agrarian society got up at 4:30 or 5a.m. with their parents to milk the cows or do any other of a long list of chores. Did growth hormones pass them by? Where were the “studies” that showed they really needed to go to bed after midnight and sleep until 10? And why weren’t their parents all being reported to the DSS? Oh, that’s right, there was no DSS. How did that generation survive?

He assumes that in times before electricity, teenagers used to wake up and fall asleep at the same time adults did. Well, they did not. Studies of sleep patterns in primitive tribes show that adolescents are the last ones to wake up (and nobody bashes them for it – it is the New Primitives with access to the media that do that) and the last ones to fall asleep – they serve as first-shift sentries during the night watch.

Even in this, the 21st century, kids who enter the military at 17 find that they can fall asleep easily at 9:30 or 10, because they know they’re going to be getting up at 4:30 or 5. Apparently the Army hasn’t read the study on circadian rhythms.

Actually, the military being the most worried by this problem is funding a lot of research on circadian rhythms and sleep and has been for decades. Because they know, first hand, how big a problem it is and that yelling sargeants do not alert soldiers make.

Kids, if you need more sleep, my study shows there’s a simple way to get it. Turn off – I mean “power down” – the cell phone, the iPod and the computer sometime before 11 p.m. Turn off the TV. Turn off the light. Lie down in bed and close your eyes.

…and sit in the dark for the next four hours, heh?

What especially drives me crazy is that so many teachers, people who work with adolescents every day, succumb to this indulgence in personal power over the children. It is easier to get into a self-righteous ‘high’ than to study the science and do something about the problem. It is easier to blame the kids than to admit personal impotence and try to do something about it by studying the issue.


My regular readers are probably aware that the topic of adolescent sleep and the issue of starting times of schools are some of my favourite subjects for a variety of reasons: I am a chronobiologist, I am an extreme “owl” (hence the name of this blog), I am a parent of developing extreme “owls”, I have a particular distaste for Puritanical equation of sleep with laziness which always raises its ugly head in discussions of adolescent sleep, and much of my own past research was somewhat related to this topic.

So, I was particularly pleased when Jessica of the excellent Bee Policy blog informed me of the recent publication of a book devoted entirely to this topic. Snooze…or Lose! by Helen Emsellem was published by National Academies and Jessica managed to get me an advanced reading copy to review.

You can also read the book online (or buy the PDF). Much more information on the topic can be found on the book webpage, on the National Slep Foundation website, on Dr.Emsellem’s homepage and the Start Later for Excellence in Education Proposal (S.L.E.E.P.) website. I strongly encourage you to look around those webpages.

Her daughter Elyssa wrote one of the chapters in the book and is promoting the book and the information relevant to teenagers at the place where teenagers are most likely to see it – on MySpace (you see – it’s not just music bands who caught onto this trick – serious information can be promoted at MySpace as well).

The main audience for this book are teenagers themselves and their parents – I think in this order although officially the order is reversed. Secondarily, the audience are teachers, administrators and officials in charge of school policy. Who this book is not targeted to are scientists and book reviewers because there are no end notes!

Anyway, considering that the main audience are teens, their parents and teachers (i.e., laypeople), the book is admirably clear and readable. The book starts out with presenting the problem – the chronic sleep deprivation of adolescents in modern society – and provides ample evidence that this is indeed a wide-spread problem. It continues with a simple primer on physiology of sleep and circadian rhythms, followed by a review of the current knowledge of the negative consequences of chronic sleep deprivation: from susceptibility to diseases, through psychological and behavioral problems, to problems of physical and mental performance.

A whole chapter – the one I found most interesting – is devoted to the role of sleep in various kinds of memory and the negative effects of sleep deprivation on learning – both declarative and episodic memory, as well as kinesthetic memory needed for athletic performance and safe driving. This is where I missed the end notes the most.

Throughout the book, Dr.Emsellem makes statements of fact about sleep that are obviously derived from research. I’d like to see the references to that research so I can evaluate for myself how strong each such statement is. Although my specialty is chronobiology (physiology, development, reproduction, behavior, ecology and evolution) of birds, and secondarily that of mammals, reptiles, invertebrates and microorganisms (I could never quite get excited about clocks in fish, fungi and plants, or molecular aspects of circadian rhythms, or medical aspects of human rhythms), I am quite familiar with the literature on sleep, including in humans.

Thus, I know that the statements in the book reflect scientific consensus but that the meaning of “consensus” is quite elastic. In some cases, it means “there is a mountain of evidence for this statement and no evidence against it, so it is highly unlikely that this will change any time soon”. In other cases it means “there are a few studies suggesting this, but they are not perfect and there are some studies with differing results, and this can stand for now but is likely to me modified or completely overturned by future research”.

Having end notes would help the expert reader see how weak or strong each one of these findings is, and would also be suggestive to lay readers that the statements in the book are supported by actual research and are not just the author’s invention as seen in so many self-help books. End notes and references add to the believability of the text even if one does not bother to check the papers out.

The book then turns to variety of factors, both biological and social, that conspire to deprive our teens of sleep, both from the perspective of a sleep researcher and from the perspective of teenagers. Little snippets of teenagers’ thoughts on the topic are included throughout the book and add an important perspective as well as make the book more fun to read. Otherwise, the “case studies”, the bane of so many psychology books, are kept to the minimum, discussed very briefly, and used wisely..

In the next section, Dr.Emsellem turns to solutions. First, she present several tests of sleep deprivation that readers can administer themselves in order to self-diagnose the problem. She then describes ten different strategies that parents and teens can work on together in order to solve the problem of sleep deprivation and all the concomittant negative effects (and Alyssa adds her own chapter on the teen perspective on how those can work). If that does not work, she describes additional methods that a sleep doctor may prescribe to help solve the problem. There is also a short chapter describing a couple of other sleep disorders, e.g., sleep apnea, that also contribute to sleep deprivation in affected individuals.

The last portion of the book addresses the social aspects of sleep deprivation and changes that parents and teens can make in their homes, as well as broader community, towards solving the problem. For adults, being a role model for the child is important and this requires paying attention to one’s own sleep hygiene.

The very last portion is really the raison d’etre of the book – how to make one’s community change the school starting times. The author presents a couple of examples of school districts in which such change was enacted, the strategies parents used to force such changes and the incredible positive results of such changes. The whole book is really designed to provide information to parents and teens who are working on changing their local attitudes toward school starting times.

The schools used to start about 9am for most of the century (and before). Then, due to the pressure from business and economic (read “busing”) woes of school districts, the school starting times started creeping earlier and earlier starting back in 1970s until they reach the horribly early times seen today in many places, requiring kids to get up as early as 5am in order to catch the school bus on time. As a result, high schoolers (and to some extent middle schoolers and college students) sleep through the first two periods in school, feel weak and groggy all day long, more easily succumb to diseases, have trouble learning and performing well in school and the athletic field, and are in too bad mood to be pleasant at home – this is not the natural state of things as much as the stereotype of the “grouchy teen” is prevalent in the society, it is mainly due to sleep deprivation and the biggest factor causing sleep deprivation are early school starting times.

In places in which enlightened and progressive school boards succumbed to the wishes of parents and students, i.e., in places in which parents and students used smart diplomatic tactics to engender such change, the positive results are astounding. The grades went up. The test scores went up. The students are happy. The parents are happy. The teachers are happy. The coaches are happy because their teams are winning all the state championships. There is a decrease in tardiness and absences. There is a decrease in sick days and even in numbers of diagnoses of ADD and depression in teens. There is a drop in teen crime. There is a drop in car accidents involving teens (by 15% in one place!). The whole county feels upbeat about it!

While the book makes me – a scientist – thirsty for end notes and references, it does remarkably well what it was designed to do – arm the parent and kids with knowledge needed to make a positive change in their communities – a change that is necessary in order to raise new generations to be healthy and successful, something we owe to our children.

We should do this no matter how much it costs, but the experiences from places in which the changes were made, contrary to doomsayers, is that there was no additional cost to this at all. The changes were implemented slowly and with everyone involved pitching in their opinion and their expertise until the best possible system was arrived at, adapted to the local community situation. No new buses were needed to be rented. No unexpected new costs appeared. And having a safe, happy community saved money elsewhere (e.g., accidents and crime rate decline). And it worked wonderfully everywhere.

So, get the book and let your child read it, you read it, give a copy to other people in your community: the teachers, the school principal, the pediatrician, the child psychologist, the school board members, the superintendent of education and the governor. This is something that is easy to do, there are no good reasons against it and the health and the future of our kids is at stake. It is something worth fighting for and this book is your first weapon.



Everything You Always Wanted To Know About Sleep (But Were Too Afraid To Ask)
Sun Time is the Real Time
What is a ‘natural’ sleep pattern?
Lesson of the Day: Circadian Clocks are HARD to shift!
Circadian Rhythms in Human Mating
Seasonal Affective Disorder – The Basics
Data for #drunksci: Daily rhythm of alcohol tolerance
Basics: Biological Clock
Spring Forward, Fall Back – should you watch out tomorrow morning?
(Non) Adaptive Function of Sleep

Comments 30 Comments

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  1. 1. geojellyroll 5:18 pm 05/20/2012

    Lack of sleep leads to obesity? Lack of sleep leads to smoking….blah, blah…blah. youth crime goe up…more baloney

    These types of ‘assumptions’ make this type of article more about blowing gas out the backside.

    I just returned fromn Korea. Kids study 14 hours a day…youth crime isn’t a fraction of what it is in the USA…nor is obesity.

    I used to get up at 4:45AM to do my chores…as did kids on nbeighboring dairy farms…we were all thin and fit.

    Articles like this full of generalizations should be pulled by the editiors of SciAm…speculative baloney under the guise of some crusading march to sell books.

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  2. 2. Bora Zivkovic 6:55 pm 05/20/2012

    @geojellyroll – if that was an attempt at impersonating and making fun of puritanical curmudgeons, I have to say you did a great job!

    If not…sigh…some people will never listen.

    BTW, the passive-aggressive plea to “…editors of Scientific American” always leaves us cold, if not slightly amused. Nobody will fall for that, and onlookers may groan or laugh. After all, I AM an editor here.

    For the onlookers and non-grouches: I republished this today because there have been numerous studies since 2006 or so when I first wrote this, making all those claims that ‘geojellyroll’ dismisses much stronger. Three excellent papers were published over just the past week and I intend to blog about them so stay tuned. This was just an introduction.

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  3. 3. roj2003 7:01 pm 05/20/2012

    ” Studies show ” – whose studies? Accreditation, please.

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  4. 4. Bora Zivkovic 7:03 pm 05/20/2012

    You mean “references”? Coming this week…

    This came from an old era when standards of citing on blogs were much more lax. I am an expert, so people trusted I know what I am talking about, no references needed (I WAS the reference). But I will fix that in the post about this next week.

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  5. 5. AstroKatie 7:16 pm 05/20/2012

    Do you have any tips for extreme night-owls who need to get up early in the morning? Is it possible to change your chronotype, or at least make the shift a bit more bearable?

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  6. 6. Bora Zivkovic 7:29 pm 05/20/2012

    @AstroKatie – short-term, you can do it. Strict feeding, exercise, bedtime and wake-up times and routines. No nightlight, etc. Take afternoon power-naps. Pay off sleep debt over the weekends.

    But long term – extreme owls should not work the jobs that require early rise. It will, in the end, be detrimental to your health (plus you’ll be grouchy for years). This is what modern society allows us now to do: choose our schedules, or work afternoon or evening shifts, or telecommute.

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  7. 7. theirongiant 7:45 pm 05/20/2012

    It’s a blog so I’d give the author some leeway. Last time I checked, there wasn’t a strict formality in writing a blog…plus he posted several references at the beginning of the page.

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  8. 8. geojellyroll 8:40 pm 05/20/2012

    “plus he posted several references at the beginning of the page.’

    huh?…he posted more speculative non-scientific articles. Self-fulfilling fluff. It’s akin to the Catholic church defending the existence of god by referencing the bible.

    This is supposedly ‘Scientific’ American. Unfortunately the website has too much space to fill and few editors that understrand what actual science is…it’s not unsubstantiated speculation in which an author zips out catchy headlined articles. He reads a book and is instant ‘expert’.

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  9. 9. Bora Zivkovic 8:54 pm 05/20/2012

    @geojellyroll – this was your second chance (refer to my commenting rule: three times and out).

    I CAN provide references if needed, probably out of memory without searching PubMed. I WILL provide new, fresh, exciting references later this week – as I said above, this is just the Intro.

    But I don’t need to provide any references. I AM the reference. This is my area of expertise. I am an expert-blogger, and this is my field. I know it inside and out. My readers come here to learn about it. You don’t have to take advantage of that opportunity. Only your loss…

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  10. 10. reidac 10:18 pm 05/20/2012

    I have heard these assertions about teenagers and their circadian phase before, and the empirical data seems sound enough, but I have never seen a satisfactory explanation for the reference for this phase — that is, the teenagers’ circadian phase is later, and the adults’ circadian phase is earlier, relative to what?

    The natural candidate is the time of sunrise or sunset, but these times vary considerably by latitude, and in the era of standardized time, can vary by more than an hour across a time zone (or even by several hours for the giant single time zone in China).

    So, in latitudes or time-zone subregions where the hours of daylight are early relative to the clock, it seems that the natural solar-driven circadian phase-shift of adolescents should be smaller relative to adults who start their day by the clock. Does this in fact happen?

    And, similarly, couldn’t you manipulate this phase shift by controlling lighting? If an adolescent’s home environment were brightly illuminated at, say, 5am, and similarly darkened by 5pm, wouldn’t that person’s sleep cycle then align with the adults’ earlier cycle? (Note that I’m not saying this is desirable, or even practical, I’m just curious if it would work.)

    Or, alternatively, is there evidence that sleep cycle phases are driven by something other than light? Presumably it’s driven by something…

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  11. 11. Bora Zivkovic 10:28 pm 05/20/2012

    Light is the most potent environmental cue. Intense blue light is needed, aimed straight at the eyes, though. The illumination, even what we perceive as bright, indoors is only up to about 1000lux. Outside, on a sunny day, it can be 100,000lux. Light needed indoors to over-ride the natural light-dark cycle would be painfully intense. But yes, it is do-able, and people do it. Nobody knows long-term consequence, or if varieties of internal clocks get out of sync with each other (e.g., light-entrained clock vs. food-entrained clock, central vs. peripheral clocks, etc).

    The post “Sun Time is Real Time” (which, yes, contains a reference to an excellent paper) deals more with the first part of your question, and the post coming up may answer some other questions.

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  12. 12. cathrin.will 11:45 pm 05/20/2012

    I’m a night worker and quite a few people still think I’m lazy because I sleep during the day, I guess this means day workers are “lazy” when they sleep at night.
    How come so many fail to make the connection that getting up later also means working later?

    And it is amazing how much someone will kick up a fuss if you wake them up at 3am, but reverse the situation and waking a night worker at 3pm is fine.

    I’m hoping the more 24/7 society becomes the more socially acceptable a variety of sleep patterns are.

    I wonder how far if at all sleeping patterns can be genetic?

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  13. 13. Bora Zivkovic 11:55 pm 05/20/2012

    It is very genetic – as I mentioned in this post, and went into more detail in the “Everything You Always Wanted To Know About Sleep (But Were Too Afraid To Ask)” post.

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  14. 14. Ourania 12:01 am 05/21/2012

    Jellyroll commenter doesn’t know what he(?) is talking about. I could never get up early in the morning. If, for some reason I have to I suffer horrible headaches for days, and my head swims. I get up between 9 and 9:30.
    I also keep Daylight Savings hours throughout the year because the change in time twice a year is hard on me.

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  15. 15. Ourania 12:08 am 05/21/2012

    Geojellyroll doesn’t know what he(?) is talking about.
    If I wake up early I suffer horrible headaches for days and my head swims.
    I also keep Daylight Savings hours all year around because the time change twice a year is too hard on me.

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  16. 16. Bora Zivkovic 12:10 am 05/21/2012

    Since it is socially acceptable to be a lark, larks have it easy and are often difficult to persuade that owls are not lazy but genetically predisposed.

    We know way beyond just the fact that it is “genetic”. We know exact details – what DNA sequences in which genes lead to their proteins getting phosphorilated (or not) in a particular spot by which other proteins – we know the details of the mechanicsm of the lark/owl chronotypes.

    Forcing an owl to wake up early every morning is like forcing a lark to stay awake way after midnight every day. Yet somehow the former is deemed OK, and the latter is supposedly rude. Yet both are like forcing a paraplegic to walk because he’s “lazy”, sitting in that chair all day.

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  17. 17. Bora Zivkovic 12:11 am 05/21/2012

    On Daylight Saving Time, see my post (linked above): “Spring Forward, Fall Back – should you watch out tomorrow morning?”

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  18. 18. LilyG, 4:40 am 05/21/2012

    Thank you! Great article! I am a mom and a teacher (teens) and it is so important what you write here. I have searched and collected some scientific information confirming what you write , a bit I paste here from an article ” Changes to this circadian rhythm occur during adolescence, when most teens experience a sleep phase delay. This shift in teens’ circadian rhythm causes them to naturally feel alert later at night, making it difficult for them to fall asleep before 11:00 pm. Since most teens wake up early for school and other commitments, this sleep phase delay can make it difficult to get the sleep teens need — an average of 9 1/4 hours, but at least 8 1/2 hours. This sleep deprivation can influence the circadian rhythm; for teens the strongest circadian “dips” tend to occur between 3:00-7:00 am and 2:00-5:00 pm, but the morning dip (3:00-7:00 am) can be even longer if teens haven’t had enough sleep, and can even last until 9:00 or 10:00 am.”

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  19. 19. JamesDavis 8:10 am 05/21/2012

    Ever since I started to school, I always thought the time schedule really sucked; from first grade all the way to graduate school. I think shutting down the schools would be a great help for everyone. We now have the technology where, because of time zones, all children and college children, can attend class in a time zone that best benefits them. If you need 10 hours of sleep and a brief exercise period, and a good breakfast before you start to class, say at 1:00PM and you live on the East coast, then you can be scheduled for class in a time zone that accommodates your schedule; say that your class would be held in one of the European countries or Australia. With digitizing textbooks and making them work like a video games, they present the perfect fix. I wouldn’t mind being an American teacher living in a European country or Australia or Japan and teaching children in New York or California. With shutting down the schools, America could afford to relocate me to anywhere in the world that would appreciate the same benefit for their children who may need a teacher located in America. I think this would be the easiest and cheapest fix for sleep deprivation and our very pricy educational system.

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  20. 20. IncredibleMouse 11:17 am 05/21/2012

    “Forcing an owl to wake up early every morning is like forcing a lark to stay awake way after midnight every day. Yet somehow the former is deemed OK, and the latter is supposedly rude. Yet both are like forcing a paraplegic to walk because he’s “lazy”, sitting in that chair all day.”

    Quote of the year.

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  21. 21. Steve3 5:18 pm 05/21/2012

    Can’t help but think getting up early has a lot to do with the demands placed on early mankind by the environment? And certainly I would expect us to be affected by the demands of a few thousand years of agrarian life.
    And I now live in a place where the longest day of daylight is 13 hours and the shortest 11 but where I grew up June 21 had light till midnight and the sun rose at 4am whilst Dcember 21 was a very short daylight day.
    So how does evolution and the distant to/from the Equator factor in?

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  22. 22. ecoligist 6:18 pm 05/21/2012

    Have you ever considered an evolutionary advantage for this? Might it have been beneficial to have part of the clan conscious at all hours of the night to sound alarm. Sleeping humans make pretty easy prey for cave bears – or for the next tribe’s forays seeking to steal mates. ‘Tis better to have a bit of annoyance by rowdy night-owl teenagers than to suffer the big bite or bash with a club.

    Sorry to bring this up: but why in the world are human babies so loud! Of what possible survival value was that back in cave-days?!

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  23. 23. Bora Zivkovic 6:23 pm 05/21/2012

    Yes, I discussed that a few times in previous posts – the need for different people to “stand sentry” at different times of night.

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  24. 24. hminkema 8:08 am 05/22/2012

    In some countries, the concrete advice that you offer is heeded. For instance in The Netherlands, both primary and secondary schools start somewhere between 08.30 and 09.00. Many kids don’t need to start before 09.15.

    Now it seems that some people here have heard about the claims that you and others have made, and they insist in delaying the starting time even more. They reason that ‘if an extra hour in the US helps, why wouldn’t an extra hour help in The Netherlands too’?

    So my question to you, Bora, is: is your advice accumulative? Are two one-hour delays better than one? What is the scientific evidence for that?

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  25. 25. Steve3 10:49 am 05/23/2012

    Thank you guys; though I’m not sure about sentry duty. I’m early to bed early to rise and …. a light sleeper. So i do sentry duty in my house, where there is actually not much need and when we go camping. I wake the dog. I don’t think bears move much at night, big cats might but don’t like fire. As for one group attacking another seems to me (from what little I know, which is IMHO very little)that primitive hunter gatherer man didn’t have much to steal .. apart from primitive hunter gatherer woman who could be grabbed whilst out gathering.
    Sleep is a fascinating subject and it’s been around as long as we have(!) and I remember the difficulties of waking and being awake as an adolescent. In my late 20′s early 30′s I used to sleep late on Sunday (till 10am) then NOT sleep Sunday night which gave me a good 8 night hours to catch up on letter writing, shoe polishing and other minor life maintenance activities. Monday I’d come home from work and be asleep by 8pm. I wasn’t married or a father then!

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  26. 26. mobla26 9:33 pm 05/23/2012

    I am fortunate to work at a job where we can set our own work schedules, within reason. (“Management,” being unimaginative, defines “within reason” to their own ends….) Anyway, I wake at 4:45 am to get to work by 7 a.m. (No choice–if I am still asleep at 5 a.m., I have the pleasure of Miss Kitty trampling me because her appetite alarm went off.) On off days, I catch another hour of sleep after feeding time before starting my day. Meanwhile, I am dangerous in the morning–I fall into walls! I am NOT a morning person–my body temperature does not begin to rise until after I awake. And yet I seem to function quite well on an “early” schedule. Perhaps it was my early training–NO ONE gave Sister Mary Immaculata grief about not being a morning person! My conclusion is that time of awakening and time of rise of body temperature are independent, and that our genes are not destiny–we can learn to do most anything. With the exception of people at the ends of the bell curve, most of us can adapt well enough to function.

    BTW, one implication of the circadian rhythms of students is that instructors’ circadian rhythms should be in synch with their students’. Should we then interview prospective teachers about their rhythms before hiring them?

    The ramifications go on. I grew up in the Central Time Zone, where TV programs come on an hour earlier than programs in the Pacific Time Zone, where I now live. So sue me–I have successfully adjusted my life to PBS’s schedule. Should television schedules be somehow rejiggered? How about opening hours for stores? How about commuter bus/rail lines? Like it or not, we have to all adjust to standard times, and the sooner the better. (Sister Mary Immaculata used to say that the sooner she got her hands on the impressionable young minds, they sooner they could be socialized.) Just a thought….

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  27. 27. mobla26 9:41 pm 05/23/2012

    Another BTW–I note that my post was time stamped as 9:33 p.m. Well, it’s 6:33 Pacific Daylight Time. Should I be living my life according to Eastern Daylight Time, home of the “pointy-headed Eastern liberal elites”? And how about this unnatural contrivance called Daylight Savings Time–does the seasonal clock adjustment also impact students’ achievement in schools?

    BBTTWW–if young people’s clocks differ from older adults’, do we allow people new to the work force to start work later than older adults do? (Revolutions have started for less!)

    So, except for you at the ends of the spectrum, SUCK IT UP!

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  28. 28. wilybadger 2:37 pm 05/28/2012

    Speaking only from my personal experience, I can say that this article really seems to reflect my teen years quite nicely.

    For most of my high school career, I attended a normal, daytime high school. I seem to recall that our schedule was something like 7:45 until 2:15. This was not a schedule on which I functioned well. I’d show up half asleep, I probably wouldn’t have eaten anything, and more than likely my homework wasn’t done. I had something around a D average and failed two courses every semester.

    For my last year, I was fortunate enough to go to a different kind of high school. Our classes ran from 2:45pm until 9:15pm. This meant that by the time I rolled into class, I was already well awake, I’d eaten something and if I hadn’t finished my homework the night before, I could finish it after I woke up, which was usually around 9:30am. My grades went up, and I didn’t get anything less than a B during that last year.

    Of course it’s possible that the real reason my grades climbed was because I had smaller classes with really good teachers. But I’m inclined to think that showing up with a full eight or nine hours of sleep, as opposed to five or six, probably played no small role.

    Currently I’m unemployed, which means that I’ve been able to let my sleep patterns be whatever they need to be. I go to sleep when I’m tired and wake up when I’m rested. I’ve noticed that my natural sleep cycle seems to be about the same as it was during that last year of high school. I tend to go to sleep around 1 or 1:30 in the morning and wake up about eight hours later. If I were offered a job that required me to be on site first thing in the morning, I’d really hesitate and have to think hard about taking it. I just don’t function well early in the morning, and that’s a simple fact. Yes, I can “suck it up,” as another commenter suggested, and if I were at a job that started at 7am, believe me, “sucking” would probably describe my performance until around 11 or so.

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  29. 29. HughMBehavior 3:21 pm 05/28/2012

    Let’s be frank here: many morning people enjoy making night owls suffer.
    I call this the “Tyranny of the Morning People.”

    I cannot cite any studies, but I have, shall we say, amassed considerable anecdotal evidence. Gonna have to roll with me common-sense style here. Geojellyroll is just the latest anecdote.

    50% or so actually think being a morning person is *morally superior.* This of course is mind-bogglingly ignorant. It’s as if they absorbed their morality from Franklin’s “early to bed, early to rise” maxim.

    But of course it’s just one group of half-hairy hominids looking to exert dominance over another. Shocking, just shocking, that they think their natural predilection is the virtuous and righteous path. (You can bet the 401k a hypocrisy homonoculus is lurking in the closet down the hall though.)

    Twas ever thus.

    Now it may sound like I’m going off on a rant here, and perhaps I am, but this is actually quite relevant:

    ***Until you address the bad attitudes of that 50% of morning people, all the fine recommendations above are moot.***

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  30. 30. Dolores Skowronek 4:06 pm 05/30/2012

    What a great article! Thank you for writing about this very important health issue. I live in a district with a 7:10 high school start time and I watch my 16 year old son struggle with a lack of sleep on a daily basis. Sadly, we are not alone. I know of many other districts that also have ridiculously early start times – some with bus pick ups as early as 5:38 and 5:45. I am a health science librarian and I can say with absolute certainty that the evidence supporting later high school start times is overwhelming. Despite what “nay sayers” like geojellyroll believe, Bora’s article is based on fact rather than assumption. Please see my bibliography for an extensive reference list:

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