Rhythmic Human
clock | May 16, 2008This 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…
clock | May 15, 2008My 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 research is somewhat related to this topic (see the bottom of this post for Related Posts).
So, I was particularly pleased when Jessica…
clock | February 29, 2008Book excerpt in today's Wall Street Journal: Chapter 6: Wired:
It is likely that insomnia will increase with the expansion of the 24-hour economy into more and more lives, and more of each life, because wakefulness and the wired world go together. The more interconnected we are, the more we communicate, and the more we communicate, the more we rely on our interconnected powers of thinking. In addition to work, many of our leisure pursuits, while seemingly soporific, actually undermine the likelihood of restful sleep, from drinking alcohol to surfing the net to watching thrillers on late-night…
clock | November 30, 2007Shift Work May Be Cancer Risk:
In an announcement to be published Saturday in the journal Lancet Oncology, the International Agency for Research on Cancer, part of the World Health Organization, will label shift work as a "probable cause" of cancer.
The designation -- rooted in the theory that the disruption of circadian rhythms could be a culprit -- puts shift work on a par with ultraviolet radiation or anabolic steroids as suspected carcinogens, but does not say it is a definitive cause of cancer, such as cigarette smoking.
A random schedule of shifts - working a couple of days a week at…
clock | October 24, 2007I am sure I have ranted about the negative effects of DST here and back on Circadiana, but the latest study - The Human Circadian Clock's Seasonal Adjustment Is Disrupted by Daylight Saving Time (pdf) (press releases: ScienceDaily, EurekAlert) by Thomas Kantermann, Myriam Juda, Martha Merrow and Till Roenneberg shows that the effects are much more long-lasting and serious than previously thought. It is not "just one hour" and "you get used to it in a couple of days". Apparently it takes weeks for the circadian system to adjust, and in some people it never does. In this day and age of…
clock | September 20, 2007Symposium Light, Performance and Quality of Life is on Thursday, 8 November 2007 in Eindhoven, the Netherlands:
Introduction
The ancient Greek already referred to the wholesome effects of the (sun)light on mankind. Ever since the industrialization, more and more people are devoid of bright daylight for a large part of the day. With the ongoing industrialization and the current information-society the number of persons that spent al large part of the day indoors further increases.
The light in these buildings is, also due to the modern trend of small windows and low lighting-levels, notably…
clock | September 18, 2007From the Independent:
The head has identified research which says that teenagers would be more likely to take in what they are learning if they started school two hours later. He is considering changing the school timetable for sixth-formers as a result.
"We have always assumed that learning early in the morning is best, probably because it is best for young children and adults," he writes. " Unfortunately, it is not true for teenagers. When teenagers are woken up at our morning time, their brain tells them they should be asleep. So they use stimulants such as coffee and cigarettes to get…
clock | August 12, 2007NBM found an excellent online article (which I have seen before but I forgot) depicting Phase-Response Curves (PRC) to injections of melatonin in humans, rodents and lizards.
Note how the shape is roughly opposite to that of a PRC to light pulses, i.e., at phases at which light elicits phase-delays, melatonin produces advances and vice versa:
The lizard PRC was actually constructed in our lab, about ten years before I joined. The article, though, gives the wrong reference to this:
Underwood, H. and M. Harless (1985). "Entrainment of the circadian activity rhythm of a lizard to melatonin…
clock | August 10, 2007Why are Orli and Joseph thinking about this in the middle of the summer? I am happy (and South enough). I am wondering if people with SAD living in the high latitudes either moved South or, being all gloomy, had a lower reproductive rate in the past, thus lowering the rates of SAD in the population.
clock | July 31, 2007
If you are one of the few of my readers who actually slogged through my Clock Tutorials, especially the difficult series on Entrainment and Phase Response Curves, you got to appreciate the usefulness of the oscillator theory from physics in its application to the study of biological clocks. Use of physics models in the study of biological rhythms, pioneered by Colin Pittendrigh, is an immensely useful tool in the understanding of the process of entrainment to environmental cycles.
Yet, as I warned several times, a Clock is a metaphor and, as such, has to be treated with thought and caution…
clock | June 13, 2007More stuff from SLEEP 2007, the 21st Annual Meeting of the Associated Professional Sleep Societies:
Sleep Deprivation Affects Eye-steering Coordination When Driving:
Driving a vehicle requires coordination of horizontal eye movements and steering. Recent research finds that even a single night of sleep deprivation can impact a person's ability to coordinate eye movements with steering.
Extra Sleep Improves Athletes' Performance:
Athletes who get an extra amount of sleep are more likely to improve their performance in a game, according to recent research.
Going To Bed Late May Affect The…
clock | April 22, 2007This is the first study I know that directly tested this - the effects of rotating shifts on longevity - in humans, though some studies of night-shift nurses have shown large increases in breast cancers, stomach ulcers and heart diseases, and similar studies have been done in various rodents and fruitflies:
Working in shifts shortens life span: Study:
A study of 3,912-day workers and 4,623 shift workers of the Southeastern Central Railway in Nagpur showed the former lived 3.94 years longer than their counterparts on shift duties, said the study by Atanu Kumar Pati of The School of Life…
clock | March 23, 2007Apparently, in Denmark, the 'larks' (early-risers) are called 'A-people' while 'owls' (late-risers) are 'B-people'. We all know how important language is for eliciting frames, so it must feel doubly insulting for the Danish night owls.
Today, in the age of the internets, telecommuting and fast-increasing knowledge about our rhythms and sleep, retaining the feudal/early capitalism work schedules really does not make sense.
And owls are by no means minority. Among kids and adults, they comprise about 25% of the population (another 25% are larks and the rest are in between). But among the…
clock | March 19, 2007It has been known for quite a while now that bipolar disorder is essentially a circadian clock disorder. However, there was a problem in that there was no known animal model for the bipolar disorder.
Apparently that has changed, if this report is to be believed:
"There's evidence suggesting that circadian genes may be involved in bipolar disorder," said Dr. Colleen McClung, assistant professor of psychiatry and the study's senior author. "What we've done is taken earlier findings a step further by engineering a mutant mouse model displaying an overall profile that is strikingly similar to…
clock | March 12, 2007This is the time when everyone is talking about the Daylight Saving Time and I always feel pressure to blog about it from a chronobiological perspective. And I always resist. As I will this year. So, here are a couple of related links instead:
Larry provides a brief history of time zones and the Dalyight Saving Time (and a cool map that goes with it).
Dave finds some data that the DST does not actually save any energy.
Among numerous newspaper articles, I thought this Boston Globe one gives the most accurate summary of what DST does to our circadian rhythms and sleep. It explains why it…
clock | March 11, 2007The most exciting thing about this study is that this is, as far as I am aware, the first instance in which it was shown that a circadian clock gene has any effect on sleep apart from timing of it, i.e., on some other quality or quantity of sleep (not just when to fall asleep and wake up, but also the depth of sleep and the amount of sleep need):
Performing Under Sleep Deprivation: Its In Your Genes:
People are known to differ markedly in their response to sleep deprivation, but the biological underpinnings of these differences have remained difficult to identify.
Researchers have now found…
clock | February 28, 2007This is a story about two mindsets - one scientific, one not - both concerned with the same idea but doing something very different with it. Interestingly, both arrived in my e-mail inbox on the same day, but this post had to wait until I got out of bed and started feeling a little bit better.
First, just a little bit of background:
Circadian oscillations are incredibly robust, i.e., resistant to perturbations and random noise from the environment. Ricardo Azevedo has described one model that accounts for such robustness in his two-part post here and here and others have used other methods…
clock | February 6, 2007Matt found a conference paper that shows that the risk of pre-term birth is the lowest in spring, rising through summer and fall and the greatest in winter.
The paper, IMHO erroneously, focuses on the time of conception (because it is an easy marker used to calculate the supposed birth-date). Matt correctly shifts the discussion to the time of birth. After all, pre-term births are much more likely to be caused by something happening around that time than anything at the time of conception.
On the other hand, Matt, though cautiously and almost tongue-in-cheek, makes an attempt at an…
clock | January 31, 2007In light of my post earlier today about the discrepanices between 'real time' and 'clock time' (or 'social time'), it is heartening that the Parliament in the U.K. wisely decided not to switch their clocks to the time the rest of Europe observes. If they did, they would be seriously out of whack. After all, at Zero Meridian in Greenwich (yup, I stood astride it, of course), midnight is really midnight - it is the middle of the time zone. Resetting it by one hour would put the Brits at the far Western edge of another time zone and they would always experience true midnight a long time (60-…
clock | January 31, 2007While study of Time-Perception is, according to many, a sub-discipline of chronobiology, I personally know very little about it. Time perception is defined as interval timing, i.e., measuring duration of events (as opposed to counting, figuring which one of the two events happened first and which one second, or measuring time of day or year).
Still, since this blog is about all aspects of biological timing, I have to point you to a new paper in Neuron (press release) about a new computer model for human time-perception.
"If you toss a pebble into a lake," he explained, "the ripples of water…