Don't Fight the Sandman

By Mark Trodden | October 10, 2005 9:33 pm

If our logs of traffic to this site are to be believed, many of you will read this post extremely late at night, much later than your parents would have thought of as bed-time. Yet more of you will read it in the wee hours, with precious little time left before you need to get up and go to work or school. And it’s not just our visitors who behave this way. You’ll often see our posts coming in after midnight, even on a school night, and even then we’re rarely straight off to beddy-byes right after posting.

It certainly seems that most people are burning the candle at both ends these days, partly because of work and family responsibilities, and partly because of the increasing availability and variety of communication and entertainment options, such as the Internet and cable television.

I’ve always been one of those people who wholly embrace such new freedoms and, since I’ve never really needed a lot of sleep, have often found myself taking advantage of them late at night and early in the morning. I frequently read or deal with email and refereeing requests after midnight, and spend part of the early morning, around 6am, reading news sites and blogs before (when things are going ideally) exercising and heading off to work. This means that I can devote most of the day-time hours, plus large chunks of many evenings, to working, plus going out with my wife or with friends on occasion. I like living this way, although I must say that, now and then (every couple of months or so), it all catches up with me and I spend a Saturday essentially curled up in bed reading a novel while watching baseball.

Many of my friends and colleagues have schedules of a similar tempo, although with different weightings of activities (often including getting up to get kids to school, which seems to be an immensely time-consuming process all on its own). We all seem pretty happy; but then again, we all also seem pretty exhausted from time to time.

But maybe we shouldn’t be so complacent. Sunday’s Washington Post has an interesting article about recent scientific studies concerning the health implications of living with a long term sleep deficit. Although, as I’ll mention briefly below, I don’t think this is a stellar science article, it nevertheless made me sit up and think.

Starting from the observation that most people need between seven and nine hours of sleep per night, the health complications that some researchers claim correlate with getting less than, say, six hours, comprise a scary list: heart disease, obesity, colon cancer, breast cancer, prostate cancer, diabetes and stroke. And I most definitely got the impression that they were just getting warmed up.

This is a timely article because the results of several new studies, with rather large sample sizes, have recently been released. I found it a little difficult to ferret out serious details of these studies from the article, but one involves 10,000 subjects, and another is out of Harvard Medical School and involved 82,000 nurses.

One thing I didn’t like was that there was an attempt to provide balance with the usual glib “but others think differently” comment:

“There are Chicken Little people running around saying that the sky is falling because people are not sleeping enough,” said Daniel F. Kripke of the University of California at San Diego. “But everyone knows that people are getting healthier. Life expectancy has been increasing, and people are healthier today than they were generations ago.”

Other researchers acknowledge that much more research is needed to prove that the apparent associations are real, and to fully understand how sleep disturbances may affect health. But …

This seems like it is an interesting and potentially important comment from a credible researcher. However, the details behind Dr. Kripke’s objections are not followed up, and one is left thinking either that his comment is unimportant or that something crucial is being ignored.

This criticism aside, I did learn some interesting nuggets about the kind of research that’s going on and what it might tell us about the potential hazards of our changing sleep habits. The connection with obesity leads to some particularly cute evolutionary speculation

The newest study on obesity, from Columbia University, is just the latest to find that adults who sleep the least appear to be the most likely to gain weight and to become obese.

Other researchers have found that even mild sleep deprivation quickly disrupts normal levels of the recently discovered hormones ghrelin and leptin, which regulate appetite. That fits with the theory that humans may be genetically wired to be awake at night only when they need to be searching for food or fending off danger — circumstances when they would need to eat to have enough energy.

“The modern equivalence to that situation today may unfortunately be often just a few steps to the refrigerator next door,” [Emmanuel] Mignot [of Stanford] wrote in his editorial [in the journal Sleep].

Despite all this, I can’t imagine dramatically changing my lifestyle any time soon – I just like it too much. However, I think I will try to be a little more alert for those signs that I’m becoming over-tired, and maybe take that lazy Saturday or the occasional lie-in a bit more frequently than I do at present. It’s for my health you understand. The fact that those sleepy mornings usually lead to deliciously decadent afternoons of baseball and contemporary literature is just a side effect of the medication.

  • Plato

    Having blog visits for statistics can make for some interesting insights as you suggest.

    As one whose has spent the last thirty years working shift work, the internal clock still does not want to adjust to those ungodly hours, but that’s part of life and part of the disruption to family, and social life, as well.

    Circadian rhythms

    Your other points are really quite interesting in terms of weight gain and such. The “metabolic clock” must take a beating as well, re-arranging sleep cycles and such I would think. Age too, has a bearing.

    I find the wee hours more productive in terms gathering a perspective views of research that I had been doing previous.

  • janet

    I’ve been hearing about these studies for a few years, and they do sound fascinating — but from what I can tell, they’ve had little or no effect on clinical practice. Not too long ago I asked an endocrinologist whether he discussed sleep habits with his diabetic patients, and he said (in so many words) “no, why woiuld I?”

    It’s hard to believe that such radical changes in sleep habits in the last ~100 years wouldn’t make a difference in our physiology. (I’ve read an estimate that the average American gets 1-2 fewer hours of sleep a night than their counterparts a century ago.) Chalk it up to cheap artificial light and cheap round the clock entertainment.

    These large cohort studies are generally done without a control group, and I think they are best construed as exploratory — mainly useful for identifying problems to study more rigorously. They can yield some interesting results, but they’re not the gold standard in medical research, and sometimes they can be misleading. For example, the justification for hormone replacement therapy to prevent cardiovascular disease in post-menopausal women came from a cohort study, but a randomized controlled trial later demonstrated pretty convincingly that HRT not only doesn’t protect against CVD, but actually increases the risk. So while these large cohort sleep studies are interesting, I have more faith in the ones that take healthy people and muck around with their sleep patterns to see what happens — and those do seem to show changes in hormonal function.

    Yawn. Time for bed. :-)

  • citrine

    Mark, it’s great that you can function effectively on little sleep. (Apparently Margaret Thatcher slept only 4 hrs a night and emerged – coiff intact – from her hotel room around 1 a.m. when the guests were required to evacuate their rooms due to a bomb or bomb scare, I can’t quite remember the exact details.)

    Benevolent smarts + requiring little sleep is a great combo! On the other hand, think of the potential destructiveness resulting from a malevolently clever person having all those extra hours to plot and plan their misdeeds.

    I’m always interested in the effects of afternoon naps (schedule permitting) on one’s productivity. There seems to be a universal dip in mental acuity in the early afternoon. A siesta is considered acceptable in some cultures, but not in the USA. It seems that one has to be always busy, frenzied and overscheduled to justify one’s existence as a productive person and taking time to sleep is seen as an act of laziness. After a certain threshold rate of busyness, one’s energy input yields diminishing returns. In my own life, I’ve learnt to spot the times I’m most alert and try to schedule my most energy-intensive activities accordingly.

  • Paul Orwin

    From Dr. Kripke’s book “Brighten Your Life” (Chapter 8, Good Sleep Habits)

    “You may have heard somewhere that 8 hours of sleep per night is necessary to be healthful. This just is not so. In our studies in San Diego, the average adult is actually asleep only between 6 and 6.5 hours a night. Moreover, The Cancer Prevention Study II showed that people who sleep 6.5 to 7.5 hours live a bit longer than people who sleep 8 hours or more Footnote – click to read. The shorter sleepers lived longer! Even people who slept as little as 3.5 hours lived longer than those who slept 8 hours or more. Certainly, if you get only 6.5 or 7 hours of sleep a night, you are probably sleeping enough.”

    Found at the first google link; Perhaps I have a career in journalism ahead of me?

  • JoAnne

    I am a sleep-nut. I need my sleep – in large doses. I literally don’t function without it. Always been that way. Ask literally anyone who knows me if they have detected when I didn’t get my sleep….Being a physcist and needing sleep is not a good combination, but it’s the way it is.

  • euan

    Are you allowing for visits from foreigners in strange timezones?

  • Dissident

    JoAnne, now that you mention it, please remind me: why is it that physicists seem to consider chronic sleep deprivation and workaholism desirable, when it’s (hopefully) common knowledge that the first things to go in a tired mind are creativity and analytic ability?

    Makes you wonder where theoretical physicists could have been by now, given a less self-defeating “professional” culture.

  • Mark

    Hi Janet. I agree entirely about the nature of these studies – random samples, messed around with under controlled conditions are much better than cohorts. All I would think one can take away from these are ideas for directions for controlled studies.

    Citrine. I agree I’m pretty lucky to function this way. When you say “…think of the potential destructiveness resulting from a malevolently clever person having all those extra hours to plot and plan their misdeeds.”, I think you already did when you mentioned Margaret Thatcher! (I’m hoping you’d never compare me to that evil woman! Besides, my hair is a mess when I get out of bed!). As I get a little older though, I am finding that I need a touch more sleep, and it’s a little annoying!

    People who are able to take short naps always seem well-refreshed after them (my Father-in-law can lie down on any surface, fall asleep immediately, and wake up fifteen minutes later ready to take on the world). Unfortunately, I’ve never been a napper. I always wake up with a mouth tasting like the bottom of a bird cage and feeling disoriented and a bit grumpy.

    Thanks for the link Paul. I guess I could have done the same. What got to me was that the journalist didn’t follow it up or, if they did, didn’t represent it in the article. If it was good work they should have presented it; if not, they shouldn’t have even mentioned him

    JoAnne, your love of sleep is indeed well documented. I recall being very impressed that you managed to come out for a drink when we both realized we were randomly at Fermilab, in neighboring hotels, late one night earlier this year. Looking back at my Orange Quark post about that, I notice two things. My title was “Why Aren’t I asleep yet?” and my post was time-stamped at 2:29a.m.

    Euan. Such visits don’t really make things worse for me, but when I travel it certainly adds to the disruption of all normal patterns.

    Dissident. I wouldn’t say sleep deprivation and workaholism are desirable to physicists. You are right that they are, to some extent, part of our professional culture (at least in the U.S.), but this is true in a variety of other professions.

    Certainly when I’m tired, creative and analytic abilities go. That’s why I tend to use these times for “busy work”.

    There are interesting cultural differences in how people describe their work. Physicists do work an awful lot (a crazy number of hours per week). However, one thing I noticed when I moved to the U.S. were the diametrically opposite manners in which people (not just physicists) talk about their work habits.

    In the U.K., the ideal is to be very successful (which undoubtedly requires a lot of hard work), but to say things like “I worked until about 5 yesterday, then went home, played a bit of footy, went out for a few bevvies, grabbed a late night curry, and felt a bit wooly this morning, so only got in around noon. Fancy a pint tonight?” In contrast, in the U.S., the ideal seems to be to never refer to having gone out, watched a movie, had a beer, played a game, generally had fun, or done anything except worked and grabbed 3 hours of sleep. Even people who work as much as we do seem compelled to exaggerate their working hours and play down relaxation time (which in academia, when taken, should involve ascetic pursuits like hiking).

  • Scott

    hmm, you sure all of those “wee hours” visits are people waking up early and not people who just havn’t made it to bed yet?…. wait I supposed to be working right now….

  • Wolfgang

    I assume you distinguish traffic from Europe and Asia in your log statistics ?

  • Mark

    Indeed I do Wolfgang. Actually, we get very late and very early visitors from those timezones also,

  • SteveM

    Going through a bereavement will totally wreck your sleep, which unfortunately is what I have discovered these past few weeks as I am going through one now. I won’t bother people with my personal issues but it does seem very relevant to this topic. Since Sept 20 I literally did not sleep for a week, certainly no more than a few hours and even pills would not work. Making up for it now though at least.

    I usually work to 3am or 4am and sleep very late and have done that for 10 years and my life is such that that it is ok for me to do that. I mentally peak from about 10pm to 2am. I would usually be one of the late night visiters to this blog. My brother literally lives on planes though and is never in any one time zone long enough to adjust. I tell him it must be bad on his health. He is younger than me but starting to look older.I believe in a lot of sleep though and would tend to agree that anything under 8 hours a night will wreck your health eventually. Being an athlete I prefer, and often need, 10. While I have no hard scientific proof I would say that many or most of the health and mental problems of people today are largely due to lack of sleep and bad diet.

    My philosophy is that there is simply no reward this life can offer you that it worth working 18 hours a day for, and no amount of money will get your health back.If you die your company or institution will get along just fine without you. Success is being able to achieve goals or achieve more with more efficient work and shorter hours not more. People totally confuse long hours with productive, effective or creative hours. This is simply not true in creative work like physics or mathematics or writing, or in many things. Just because you have worked 12 hours straight on something or on some problem does mean you have necesarily gotton anywhere with it at all. Short bursts of effort work best(at least with me) then giving the mind a break from it. I also believe such problems are solved in your mind when you sleep and new ideas emerge, not when you are at your desk.

    Sleep also has a powerful healing effect but it remains something of a mystery. For some reason if we don’t have rem sleep/dreams we can’t survive or function.

  • janet

    Mark — Unfortunately, doing without sleep does harder as you get older. When I was in my 20s, I could stay up for a couple of days straight and be basically functional; by the time I was 30, that was impossible. I also started being able to nap a few years ago, when I never did before. Most of the time, though, when I “nap,” what I really do is lie down and listen to music with my eyes closed for 20 minutes. Conventional wisdom used to be be that elderly people need very little sleep, but this isn’t necessarily true: they do tend to sleep less, but more because they have trouble sleeping than because they need less sleep.

    Paul — That quote from Kripke is interesting. I think it’s a little bit of a red herring, though. Life expectancy is one measure of health, but it’s complicated by the fact that we do such a good job, these days, of keeping sick people alive. And I’m not just talking about people sick enough to be in the hospital, but about all the people with diseases that used to be fatal and now are “manageable,” and thus chronic.

    Steve — I’m sorry, that sounds rough. Grieving does throw off most basic daily patterns — sleeping, eating, working. I hope it’s getting better for you. I agree with you about working long hours, but there are lucky people for whom the work is its own reward.

    Sort of related — A while ago I had an idea for a science fiction setting: a planet of intelligent creatures (could be human, doesn’t really matter) with the peculiar physiological property of not being able to reset their sleep-wake cycles. Wherever you were born, your cycle would be set to that time zone and you couldn’t readjust when traveling east or west. It was fun to think about how that might affect trade, economic development, and various other social issues. Unfortunately I’m not a fiction writer, so I never did anything with it.

  • Elia Diodati

    How about the possibility of people in Europe / Asia reading Cosmic Variance?

  • janet

    Just after my last comment, I found this in the Sept. 7 issue of the Journal of the American Medical Assn: “Neurobehavioral Performance of Residents After Heavy Night Call vs. After Alcohol Ingestion.” You’ll be glad to know that they didn’t get the residents liquored up and then turn them loose on patients — they used a battery of tests to assess their performance. Anyway, they concluded that “post-call performance impairment during a heavy call rotation is comparable with impairment associated with a 0.04 to 0.05 g% blood alcohol concentration…” (Legal intoxication is 0.08 or so.)

  • Mark

    What about it Elia? We certainly have many readers from Europe and some from Asia also. If your question is along the lines of comment 10, you’ll see that I answered in comment 11. If you’re asking something else I’ll try to answer if you expand a little. Thanks.


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Cosmic Variance

Random samplings from a universe of ideas.

About Mark Trodden

Mark Trodden holds the Fay R. and Eugene L. Langberg Endowed Chair in Physics and is co-director of the Center for Particle Cosmology at the University of Pennsylvania. He is a theoretical physicist working on particle physics and gravity— in particular on the roles they play in the evolution and structure of the universe. When asked for a short phrase to describe his research area, he says he is a particle cosmologist.


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