chronobiology
clock | July 14, 2008There is now a Sleep and Circadian group on Graduate Junction so if you are a student or postdoc in the field, and enough of you join up, we can see if can get some discussions going....
clock | July 1, 2008Came to my e-mail inbox:
The Harvard Summer School is pleased to announce the addition of a
three-day special seminar for teachers in the sciences. Based on the
well-known "Chautauqua Seminars" model, there is no cost to participants
other than a $50 registration fee. The course is taught by distinguished
Harvard faculty and provides an opportunity for invited scholars to share
new knowledge, concepts, and techniques directly with teachers in ways
which are immediately beneficial to their teaching. The primary aim of
this rejuvenating session is to enable teachers to keep their teaching…
clock | June 26, 2008Marc Dingman is touching on my own favorite topic: It's All About Timing: Circadian Rhythms and Behavior
And SciCurios goes only millimeters below the suprachiasmatic nucleus: Diabetes Insipidus as a Sequel to a Gunshot Wound of the Head
Both posts well worth your time.
clock | June 25, 2008Believe it or not, this appears to have something to do with their circadian rhythms!
Back in the 1960s and early 1970s, there was quite a lot of research published on the circadian rhythms in earthworms, mostly by Miriam Bennett. As far as I can tell, nobody's followed up on that work since. I know, from a trusted source, that earthworms will not run in running-wheels, believe it or not! The wheels were modified to contain a groove down the middle (so that the worm can go only in one direction and not off the wheel), the groove was covered with filter paper (to prevent the worm from…
clock | June 12, 2008Two of my SciBlings have recently covered papers that my readers should find interesting:
Joseph: Bright Light and Melatonin Treatment Improves Dementia:
A study published in JAMA indicates that treatment with bright light alone (1,000 lux), or bright light combined with melatonin, can improve symptoms in patients with dementia. Melatonin alone appeared to have a slight adverse effect.
Chris Chatham : Time Perception: In the Absence of "Time Sensation?":
In their newly in-press TICS article, Ivry and Schlerf review the state of the art in cognitive modeling of time perception - perhaps the…
clock | May 30, 2008Today in PLoS Genetics: a nice review of some interest to my readers: When Clocks Go Bad: Neurobehavioural Consequences of Disrupted Circadian Timing by Alun R. Barnard and Patrick M. Nolan:
Progress in unravelling the cellular and molecular basis of mammalian circadian regulation over the past decade has provided us with new avenues through which we can explore central nervous system disease. Deteriorations in measurable circadian output parameters, such as sleep/wake deficits and dysregulation of circulating hormone levels, are common features of most central nervous system disorders. At…
clock | May 30, 2008In the Journal of Circadian Rhythms:
A new approach to understanding the impact of circadian disruption on human health (pdf):
Background
Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day. Disruption of circadian rhythms has been associated with a variety of maladies. Ecological studies of human exposures to light are virtually nonexistent, however, making it difficult to determine if, in fact, light-induced circadian disruption directly affects human health.
Methods
A newly developed field measurement device recorded circadian light exposures…
clock | May 29, 2008I was wondering what to do about the Classic Papers Chellenge. The deadline is May 31st, and I am so busy (not to mention visiting my dentist twice week which incapacitates me for the day, pretty much), so I decided to go back to the very beginning because I already wrote about it before and could just cannibalize my old posts: this one about the history of chronobiology with an emphasis on Darwin's work, and this one about Linnaeus' floral clock and the science that came before and immediately after it.
In the old days, when people communed with nature more closely, the fact that plants and…
clock | May 23, 2008No matter how cutesy the acronim SAD is. Joseph reports on a study that links SAD to serotonin. But serotonin itself may not be necessary to understand how SAD works, though an intimate link between serotonin and melatonin (the former is the biochemical precursor of the latter) suggests that serotonin should be looked at in this context.
Also, if you suffer from SAD you should be very careful preparing for your long-distance travel: getting jet-lagged may trigger a bout of a few days of depression regardless of the time of year.
clock | May 22, 2008
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 | May 20, 2008What it really means when we are talking about babies "sleeping through the night" (from September 22, 2005)
-----------------------------------------Trixe Update is a blog that is very unusual. First, just looking technically, the posts go from top to bottom instead of the latest post being on the very top. Second, the whole blog is devoted to the day-by-day growth and development of Trixie, from birth until about the age of two.
The graph on the right (and there are many different graphs there) shows the sleep-wake cycle. Unfortunately, the first four months - the most interesting months…
clock | May 19, 2008The fourth part of a four-part series on the topic, this one from April 02, 2006....
This being the National Sleep Awareness Week and on the heels of the recent study on sleep of adolescents, it is not surprising that this issue is all over the media, including blogs, these days.
I have written about it recently several times. I present some science and some opinion here and add a little more science and much more opinion here.
You can look at media coverage here and listen to an excellent podcast linked here. Some basic underlying science is covered here.
All of this targets highschoolers…
clock | May 19, 2008As you know, I am currently in Florida, at the 20th Anniversary meeting of the Society for Research on Biological Rhythms, that is, my own society. I have not been since 2002, so I am surprised to see how many people remember may face and are happy to see me.
I am also surprised to hear how many people in the field read this blog - some more some less regularly - and even use the ClockTutorials and some other Chronobiology posts in teaching their courses on Biological Clocks. I would have know this before if they would just post comments here!
What I am not surprised, yet am pleased, is…
clock | May 18, 2008This is the third part of the series on the topic, from April 01, 2006...
This being the National Sleep Awareness Week and in the heels of the recent study on sleep of adolescents, it is not surprising that this issue is all over the media, including blogs, these days.
I have covered this issue a couple of times last week, e.g., here, here and here. 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…
clock | May 17, 2008I just had nice seafood dinner while watching the sunset over the water with this guy, down in sunny Florida. Readers of this blog have met him before, here and here.
I also saw Erik Herzog, who is familiar to all of you from, e.g., here, here, here and here. I heard him give a presentation about the ways to get an NSF grant in the circadian field.
I am about to see Chris Steele as well.
I attended a Memorial Symposium on Melatonin in honor of Aaron Lerner.
And talked to several people about PLoS already - I am REALLY doing my job.
I am suprised how many people recognize me and are happy to…
clock | May 17, 2008
Earlier this year, during the National Sleep Awareness Week, I wrote a series of posts about the changes in sleep schedules in adolescents. Over the next 3-4 hours, I will repost them all, starting with this one from March 26, 2006. Also check my more recent posts on the subject here and here...
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…
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 | May 13, 2008
Much of the biological research is done in a handful of model organisms. Important studies in organisms that can help us better understand the evolutionary relationships on a large scale tend to be hidden far away from the limelight of press releases and big journals. Here's one example (March 30, 2006):
--------------------------------------------------Short answer: nobody knows. Nobody has looked yet. Most of the research in biology is, quite rightfully, performed in just a handful of standard models. A sponge is not a standard animal lab model.
Should one expect sponges to have…
clock | May 4, 2008
When teaching human or animal physiology, it is very easy to come up with examples of ubiqutous negative feedback loops. On the other hand, there are very few physiological processes that can serve as examples of positive feedback. These include opening of the ion channels during the action potential, the blood clotting cascade, emptying of the urinary bladder, copulation, breastfeeding and childbirth. The last two (and perhaps the last three!) involve the hormone oxytocin. The childbirth, at least in humans, is a canonical example and the standard story goes roughly like this:
When the…
clock | May 4, 2008This post from March 27, 2006 starts with some of my old research and poses a new hypothesis.
The question of animal models
There are some very good reasons why much of biology is performed in just a handful of model organisms. Techniques get refined and the knowledge can grow incrementally until we can know quite a lot of nitty-gritty details about a lot of bioloigcal processes. One need not start from Square One with every new experiment with every new species. One should, of course, occasionally test how generalizable such findings are to other organisms, but the value of models is hard…