Rhythmic Human
clock | April 23, 2009I regularly get Google News alerts for articles that contain the word "circadian" in them. Most of them are not too exciting, but when a really good one comes along, I like to point it out to you. Today, you should go and read Larks, Owls and Hummingbirds, a guest post by Leon Kreitzman over on Olivia Judson's blog. Highly recommended - about human circadian rhythms, chronotypes (i.e., owls and larks), etc., both from a scientific and a societal point of view.
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Related:Everything You Always Wanted To Know About Sleep (But Were Too Afraid To Ask)
Books: Snooze...Or Lose! - 10…
clock | April 16, 2009Ask the pilot:
Ask yourself this: Whom would you prefer at the controls of your plane on a stormy night, a pilot who smoked a joint three days ago, or one who had six hours of sleep prior to a 13-hour workday in which he's performed half a dozen takeoffs and landings? The first pilot has indulged in a career-ending toke; the second is in full compliance with the rules. I have to assume that the FAA realizes the foolery of such enforcement policies, but it nonetheless chooses to put its resources into drug testing and other politically expedient issues. Meanwhile it procrastinates, performing…
clock | April 2, 2009Nice four articles:
The Gears of the Sleep Clock By Allan Pack:
When people have trouble sleeping--such as, in extreme cases, shift workers--those problems are not always rooted in disturbances in circadian rhythm, argues the University of Pennsylvania's ALLAN PACK. Instead, his studies of sleep have shown that the master clock is only one player in the molecular control of sleep.
Sleep adjusts fly synapses by Bob Grant:
New findings support a controversial hypothesis about the biological role of sleep: Snoozing may be a way for the brain to clear clutter accumulated after a hard day of…
clock | March 26, 2009BBC 4 had a fascinating half-hour show yesterday, interviewing Till Roenneberg and Helen Emsellem on all sorts of fascinating new findings in the field of human chronobiology. Well worth a listen. But hurry up as the podcast is available only for another six days! (what do they do afterwards? why such a limited time? archives should be freely available forever).
clock | March 12, 2009Circadian rhythms: Of owls, larks and alarm clocks in Nature News (download PDF while the article is still freely available), written by Melissa Lee Phillips is an excellent overview of the current state of knowledge about human circadian rhythms, underlying genetics, and circadian disorders.
I get several Google Alerts every day for media articles about clocks and most of them are too 'meh' for me to bother linking here, but this one is good and worth your time. J'approve.
Related....
clock | March 7, 2009Yup, it's tonight.
If you were around here a few months ago, the day after the Fall Back day, you probably read this post.
Disregarding the debate over rhetoric of science, that is probably my best, most detailed explanation for what happens to our bodies on those too strange days of the year - Spring Forward and Fall Back day.
Spring Forward is much more dangerous, so be very careful in the mornings next week, especially on Monday. Take it easy, get up slowly, be a little late for work if you can afford it. Life and health are more important than a few minutes of work and being punctual on…
clock | November 22, 2008NYTimes:
Eliminating daylight time would thus accord with President-elect Barack Obama's stated goals of conserving resources, saving money, promoting energy security and reducing climate change.
Eugene Sandhu:
In order to conserve energy, President-elect Barak Obama should eliminate daylight saving time.
Boing Boing:
President-elect Obama wants to get rid of daylight saving time in the United States to conserve energy.
The game of broken telephones? Or lack of reading comprehension, or just wishful thinking? I though we were the Reality-Based Community.
More....
clock | November 10, 2008Related to this discussion, there is a new interesting study out - Daily rhythms in blood vessels may explain morning peak in heart attacks:
It's not just the stress of going to work. Daily rhythms in the activity of cells that line blood vessels may help explain why heart attacks and strokes occur most often in early morning hours, researchers from Emory University School of Medicine have found. Endothelial cells serve as the interface between the blood and the arteries, controlling arterial tone and helping to prevent clots that lead to strokes and heart attacks, says Ibhar Al Mheid, MD, a…
clock | November 2, 2008If you live in (most places in) the United States as well as many other countries, you have reset your clocks back by one hour last night (or last week). How will that affect you and other people?
One possibility is that you are less likely to suffer a heart attack tomorrow morning than on any other Monday of the year. Why? Let me try to explain in as simple way as possible (hoping that oversimplification will not lead to intolerable degrees of inaccuracy).
Almost all biochemical, physiological and behavioral parameters in almost all (at least multicellular) organisms display diurnal (daily…
clock | September 29, 2008Once a year, I go back to my alma mater and do a guest lecture about biological clocks in an Anatomy & Physiology class. Knowing how many pre-meds are among the 200 students in the room, I try to start with some examples of rhythms in human physiology (and disease), and the first one is body temperature, busting the myth that 98.6F (37C) is the "normal" temperature:
Now Orac links to an excellent post that explains it all - the entire history of the idea that 37C is normal and what the real difference, means and fluctuations there are. Read the whole thing.
clock | August 1, 2008How do I try to beat jet-lag:
- book an overnight flight that lands at the destination in the morning, if possible. This really helps.
- start gradually shifting my daily schedule of meals, activities, sleep, a few days in advance.
- once I pass security and have about an hour before take-off, I take clonapen (not sleeping pills and no, not melatonin, though some people swear about it - it makes me depressed because of my extreme owl-eness and SAD). This (as I am a little anxious of flying) helps me fall asleep very quickly, sometimes before we are airborn, sometimes right after they serve…
clock | July 19, 2008Carl Zimmer: How Your Brain Can Control Time:
For 40 years, psychologists thought that humans and animals kept time with a biological version of a stopwatch. Somewhere in the brain, a regular series of pulses was being generated. When the brain needed to time some event, a gate opened and the pulses moved into some kind of counting device.
One reason this clock model was so compelling: Psychologists could use it to explain how our perception of time changes. Think about how your feeling of time slows down as you see a car crash on the road ahead, how it speeds up when you're wheeling around a…
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 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)
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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 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, 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…