The Human Body Clock (Circadian Rhythm)

anne_of_28_days

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does anyone remember the deprivation experiment that took place about 15 years ago in or around Carlsbad Caverns, New Mexico? College students lived in seclusion deep underground for...i think months. they had no clocks. i think it was two guys and one girl, in isolated confinement. afterward, they were so messed up they couldn't go back to school and months later i think the girl committed suicide.
 

James_H

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I remember seeing an advert for a film that sounds similar (maybe based on the events?) called "the hole".
 

Electric_Monk

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I saw "The Hole", it was quite good, although I felt it wasn't much about deprivation, I have included a description here to allow people to avoid spoiling it if they haven't watched it but want to. The IMdb entry also has quite a good write-up, without spoilers apparently. I do recall hearing of a deprivation experiment where they were given all the normal luxuries of home except clocks or daylight, the reason being to find out how long our days are biologically, and the only thing people mentioned of note was that they weren't 24 hours, but a little off ;)
 

anne_of_28_days

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yes, they kept in-depth, 24 hour diaries, but the 24 hours changed to more like 21 or 22. and i can't remember if they thought they were sleeping 8 hours, but were really sleeping 2 ... or 18. a longer sleep seems to make more sense, but i almost feel it was a much shorter sleep... anyway, sleep was totally screwed up.
 

rantaclaws

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As I recall, sleep isn't completely screwed up, nor did anyone go insane, but the natural human day length is closer to 25 hours than 24.
 

James_H

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I remember seeing a program that claimed that the natural amount of time for people to sleep each night was 16 hours, but that electric lighting had messed this up, somehow.
 

Feyri

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It was a study done by psychologists, IIRC. I studied the experiment in my psych class several years ago, I will try to dig it out when I'm at home later. As far as I can remember right now, there was one guy who was put underground and yes, there were no clocks or anything. Though I seem to remember that TV programs were 'piped' down to him as a form of entertainment. His body-cycle changed from the 24 hours that we live by today to something like 25 or 26 hours, and yes he did sleep more but I reckon that was probably more due to boredom than anything else.
 

Mighty_Emperor

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Feyri: That experiment is pretty well known (although I'd still appreciate any information you have) - Play Dead seems to be refering to other experiments.

The phrase has been eluding me for a bit but once "Circadian Rythms" floated to the surface of my brain I was able to dig up more info:

To prove that our circadian rhythm isn't just a reaction to external stimuli like daylight, alarm clocks or watches, but much more an internal biological action, two German scientists conducted an experiment in which they locked up volunteers in a bunker where no sunlight could enter. (1) The volunteers were kept there for one month without having any idea whatsoever of the time it really was outside and were encouraged to go to bed whenever they wanted. The results of the experiment after one month showed that the natural repetitive cycle for these volunteers came to "settle" at above 24 hours, at about 25 hours (of which one third was spent asleep)!

In a human experiment, people were left in a cave and provided with electricity which they were allowed to control. The humans gradually adjusted to a 48 hour cycle, with 18 hours of sleep and 30 hours of activity. (2)

library.thinkquest.org/25553/english/basics/body/rhythm.shtml
Link is dead. The MIA webpage can be accessed via the Wayback Machine:
https://web.archive.org/web/2005030...st.org/25553/english/basics/body/rhythm.shtml


Information on the experiments carried out by Michel Siffre

In 1962, he spent two months in the caves of Scarrasson, in the southern Alps. After 61 days on an underground glacier with no time reference, he resurfaced on September 17th believing the date was August 20th.

In 1972, the speleologist supervised other similar experiments before going down again into the Midnight Cave where he remained for 205 days, in collaboration with the Lyndon Johnson Space Center of Houston (NASA). "My brain would make automatic adjustements because it had memorised the previous experiment and yet I was still 2 months out." "We have made a real contribution to chronobiology.But I didn't only study human rhythms out of time, I also analysed sleep, using electro-encephalographic studies."

On November 30th 1999, Michel Siffre, by then aged 60 and a veteran of French scientific speleology, settled in an out of time context in the Grotte de Clamouse. This was how he stumbled into the 21st century. Deep in the bowels of the Grotte de Clamouse, the sixty-year-old pursued his experiments and went through a full range of tests, with the help of his own experience and the latest technologies available. All the indicators concerning his health were monitored live from the surface using a Thomson-designed computer system (deprived of all time markers). Michel Siffre studied the influence of ageing on the way the human body reacts when there is no time bearing. He emerged from the cave on 14th February 2000. The aim of this experiment was to study the influence of ageing on the alterations of circadian rhythms (the alternation between waking and sleep).

grottedeclamouse.com/en/siffre/siffre.asp?dossier=siffre&fichier=siffre
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https://web.archive.org/web/2004081...ffre/siffre.asp?dossier=siffre&fichier=siffre


The sleep-wake cycle, one of the strongest circadian rhythms in the body, resets itself everyday in response to sunlight. A famous experiment carried out in 1938 showed the extremely strong effect sunlight has on circadian rhythms. Two sleep researchers, Nathaniel Kleitman and Bruce Richardson, spent thirty-three days in Mammoth Cave in Kentucky. During that time, they lost total track of time. The researchers awoke when their body told them to and fell asleep when they were sleepy. Soon, the researchers were falling asleep about an hour later than they normally would have if they were at the surface, exposed to the daily cycle of sunlight and darkness, sunlight and darkness. At the end of the first week, they were heading to bed about seven hours later than everyone else.

healthedit.com/writing/sleep.htm
Link is dead. The MIA webpage can be accessed via the Wayback Machine:
https://web.archive.org/web/20101115055526/http://www.healthedit.com/writing/sleep.htm


See also:

http://www.abc.net.au/science/bernie/news/s34784.htm

Edit: See also discussion here:

https://forums.forteana.org/index.php?threads/sleep-deprivation-survey-poll.992/

https://forums.forteana.org/index.php?threads/sleep-deprivation.801/
 
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athyra

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The 25 hour circadian rhythm only makes sense. It probably evolved some ways back.

The moon's tidal effects actually has actually slowed the rotation of the earth, I'm sure if anyone is interested enough they could pinpoint the date, give or take 10 million years or so, just when this rhythm became hard coded.

It might stretch way further than I thought, because I know certain parasites have a rudimentary cycle as well, as they only come out at night to lay eggs.
 

anne_of_28_days

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thanks for the links, emperor.
i'm beginning to think i imagined the whole experiment. nobody remembers anything about it. looking back, i realize it had to be more like 25 yrs ago. (yikes!) i read about it in a short-lived science magazine. (US) it even had whole sections of the female participant's daily diary, and you could see how quickly she fell apart.
 

Mighty_Emperor

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Play Dead said:
thanks for the links, emperor.
i'm beginning to think i imagined the whole experiment. nobody remembers anything about it. looking back, i realize it had to be more like 25 yrs ago. (yikes!) i read about it in a short-lived science magazine. (US) it even had whole sections of the female participant's daily diary, and you could see how quickly she fell apart.

Well I doubt you are imagining it ;)

There were probably a lot of experiments done on this kind of thing - you might need to track down a book on it to find what you are looking for. However, this bit qutoed above:

In a human experiment, people were left in a cave and provided with electricity which they were allowed to control. The humans gradually adjusted to a 48 hour cycle, with 18 hours of sleep and 30 hours of activity. (2)

is thisHas this reference:

(2) Nightwatch: the Natural World from dusk to dawn. New York, Facts on File. 1983.

Ring any bells?
 

anne_of_28_days

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yes, that could be the study i'm talking about. strange that it isn't easier to find info when one of the subjects killed herself -- not directly afterward, but months...maybe even a year later.
 

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The moon's tidal effects actually has actually slowed the rotation of the earth, I'm sure if anyone is interested enough they could pinpoint the date, give or take 10 million years or so, just when this rhythm became hard coded.

If the Earth was rotating faster then the days would be shorter. So shouldn't we have evolved a 23 hour rhythm rather than a 25?
 

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As a bit of an aside The Hole is going to be on Channel 4 on Sunday at 10PM, if anybody wants to see it :)
 

Bilderberger

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Recently I have been reading quite a lot about baby's sleeping patterns.

One thing I read reminded me of a rather bizarre fact. According to human biologists - the human body runs on a 25 hour body clock day as opposed to the 24 hours in a day.

Why on earth is this the case? How could evolution cock this up so badly? One has to assume that there is an evolutionary advantage - but I can't think of it.
 

Mighty_Emperor

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Circadian Rythms are touched on in a thread on sleep deprivation experiments here:

http://www.forteantimes.com/forum/showthread.php?s=&threadid=16376&highlight=circadian

There I found a passage that without external stimuli people adjust to a 48 hour day "18 hours of sleep and 30 hours of activity". Someone else suggested that a 25 hour day may be hardwired from earlier times (but thinking about that I'm unsure that would work - the moon slows down our rotation which means days are getting longer).
 

fluffle9

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Emperor said:
Someone else suggested that a 25 hour day may be hardwired from earlier times (but thinking about that I'm unsure that would work - the moon slows down our rotation which means days are getting longer).

even if days were getting shorter i'm pretty sure that we'd be talking about far too long a timescale anyway - ie the length of the day can't possibly be changing fast enough that we could have a 25-hour day as an evolutionary relic from a time when there was one.

the only thing i can think is that humans used to do a hell of a lot more excercise than most do today. perhaps they would have been tired sooner. i mean, the studies that showed that we have a 25-hour body clock were probably conducted on people who spend most of their time sitting on their arses, instead of chasing after antelopes or walking miles to the nearest source of clean water. perhaps if they'd done the studies on extremely active people they would have found that they work to a 24-hour day.
 

PeniG

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The 25-hour circadian rhythm permits the body to adjust gradually to gradual changes in sunrise and sunset throughout the year and as you move around the landscape from the winter hunting grounds to the summer gathering grounds.

In modern times, understanding the 25-hour cycle allows you to adjust to jet lag and shift changes without the familiar disruption, if you can control your time well enough to do so. Basically, if you shift your schedule forward by an hour a day - go to bed and lie in later - until you achieve your new time zone, you'll never have that three-day hunk of inefficient misery. I'd give you a citation, but I'd have to look through about three years worth of diaries and then I'm not sure which sleep-disorder book I read it in.

Now if I could just use that information somehow to cure insomnia, I'd be doing all right.
 
A

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I recall an experiment from quite a few years ago, where a series of volunteer subjects were placed in an underground chamber. They had everything they needed - food, water, bedding, exercise machines, hygienic living conditions - but they had no slightest way of telling the time. They had to press a button each time they went to bed, got up, ate lunch etc etc. This went on for several weeks, to see what length of "day" they would adjust to, cut off from the outside world.
Interestingly, iirc there seemed to be no particular pattern to which way people headed. Some would settle down to a longer rhythm than the normal day, e.g. an 18-hour waking period followed by 12 hours sleep. Others went the other way, settling into a "day" of only 10 hours waking and 7 hours sleep. Personally I doubt that there is any particular pattern "hardwired" into us at all. If we lived on another planet, with longer or shorter days and nights, we could probably adjust pretty well, as long as the difference wasn't extreme.

Big Bill Robinson
 

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some cold theory to keep you going...

BMJ 1998;317:1704-1707 ( 19 December )
Clinical review

The brain, circadian rhythms, and clock genes

Michael Hastings, reader in neuroscience.

Department of Anatomy, University of Cambridge, Cambridge CB2 3DY

Every day we experience profound changes in our mental and physical condition as body and brain alternate between states of high activity during the waking day and recuperation, rest, and repair during night time sleep. These cycles are not a passive response to the world around us: they are pre-adapted, driven by an internal clock. We know this because when human volunteers are held in experimental isolation and deprived of any temporal or social cues, they still show daily cycles of sleep and wakefulness, in core body temperatures, and urinary output (fig 1). 1 2 As with all biological processes, the clock driving these cycles is slightly imperfect, therefore the measurable rhythms free run with periods of slightly less than or greater than one solar day, hence circadian (approximately a day). Notwithstanding this inaccuracy, the circadian clock is extremely robust. It is capable of continuing for several months and with a reproducibility to within a few minutes per cycle....

[continued: http://bmj.bmjjournals.com/cgi/content/full/317/7174/1704
 

WhistlingJack

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Bright idea creates '25-hour day'

Our natural daily 24-hour cycle could be stretched by an extra hour safely and simply by exposure to pulses of bright light, research suggests.


Experts say it could prove useful for astronauts adapting for long-term missions to Mars - where a day lasts an extra 40 minutes.

The team, from universities in the US and France, tested the light treatment successfully on 12 volunteers.

The study features in the Proceeding of the National Academy of Sciences.

Many species, including humans, have natural "circadian rhythms" set to match the standard length day on Earth.

The contrast between exposure to daylight and night-time darkness is thought to adjust and maintain this clock, which helps makes sure the body is working as effectively as possible at times of day when maximum alertness is required.

Scientists already know that it is possible to interfere with the human circadian "pacemaker" by controlling exposure to light.

The latest research project, shared between Lyon University in France, and Harvard University and Medical School in the US, looked at whether it was possible to "fine-tune" these alterations to achieve a precise result.

Humans do not have precise 24-hour cycles to begin with, and all of the 12 volunteers had cycles ranging from 23.5 to 24.5 hours.

After allowing them to sleep and wake normally for a few days, a new regime was imposed, with artificial "days" produced by a combination of low light and very bright pulses of light near the end of the intended "wakeful" hours.

After 30 days, scientists found that a combination of light brightness and pulses was able to manipulate the circadian rhythm, over time adding approximately one hour to each subject's day.

The researchers said that there were numerous situations in which the ability to do this might be useful.

"Jet-lag, shift work and circadian disorders such as advanced and delayed sleep phase syndromes are all associated, to different extents, with a condition where the circadian system is out of synchrony with the light/dark cycle," the wrote.

Another possible application might be during long space missions - and to allow astronauts to adapt to longer days on Mars.

"In these situations, sleep and circadian disruptions could have serious consequences on the effectiveness, health and safety of astronaut crews," the team told the PNAS journal.

They scientists suggested that the light "treatment" could be administered as Mars astronauts tended crops at the appropriate times of day in a brightly lit greenhouse module.

However, the volunteers in the study were all closeted in a laboratory for more than 60 days in total to avoid unwanted exposure to daylight interfering with the experiment.

Professor Derk-Jan Dijk, from the Surrey Sleep Research Centre, UK, said the study suggested that circadian cycles could be controlled more precisely - but only in controlled environments in which people can be exposed to precise light levels at the right times of day.

He added: "If you have, for example, shift workers on oil rigs who never see the light of day, or people travelling through space, it may be possible to use these methods.

"For this to work, you have to able to avoid light sometimes, which is more difficult in real-life situations, where people are exposed to different levels of light as they go about their normal day-to-day business."

Story from BBC NEWS:

Published: 2007/05/16 09:05:02 GMT

© BBC MMVII
 

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If there was going to be an extra hour in my day I'd rather it was at night so I could get a bit more sleep. I bet that'd have more effect on productivity than making people stay awake for an hour longer.
 

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Hasn´t there already been these things on the market to change your rhytm for quite a while? Some things with lights you strap to the back of your knees during flights, to avoid jetlag.
 

rynner2

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Body clock 'alters' immune system
By James Gallagher, Health and science reporter, BBC News

The time of the day could be an important factor in the risk of getting an infection, according to researchers in the US.
They showed how a protein in the immune system was affected by changes in the chemistry of the body through the day.
The findings, published in the journal Immunity, showed the time of an infection changed its severity.
An expert said drugs were likely to take advantage of the body clock in the near future.

Plants, animals and even bacteria go through a daily 24-hour routine, known as a circadian rhythm. Jet lag is what happens when the body gets out of sync with its surroundings after crossing time zones.
It has been known that there are variations in the immune system throughout the day. Researchers are now drilling down into what causes the details.

The immune system needs to detect an infection before it can begin to fight it off. Researchers at Yale University School of Medicine were investigating one of the proteins involved in the detection process - Toll-like receptor nine (TLR9), which can spot DNA from bacteria and viruses.
In experiments on mice, the scientists showed that the amount of TLR9 produced and the way it functioned was controlled by the body clock and varied through the day.
Immunising mice at the peak of TLR9 activity improved the immune response, the researchers said.

They said humans with sepsis, blood poisoning, were known to be at a greater risk of death between 02:00 and 06:00.
When testing mice, the severity of sepsis depended on the time of day infection started and coincided with changes in TLR9 activity.

Prof Erol Fikrig, who conducted the study at Yale University, said they had found a "direct molecular link between circadian rhythms and the immune system", which could have "important implications for the prevention and treatment of disease".
He added: "It does appear that disruptions of the circadian clock influence our susceptibility to pathogens."

Dr Akhilesh Reddy, who is researching circadian rhythms at the University of Cambridge, said it was "known long ago" that timing had an impact on the immune system, but this was "one of the first forays" into the reasons why.

The implications for healthcare could mean that drugs need to be given at certain times of day in order to make them more effective, or drugs could be made which actually target the body clock to put the immune system into its most active phase.

Dr Reddy said drug companies were "all switching onto this" and were "now screening drugs at different times of the day".
He could see the body clock impacting medicine "within 10 years".

http://www.bbc.co.uk/news/health-17059498
 

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It's about time this thread got a reboot! A fascinating program, presented by Sir Terry Wogan, no less, reveals why teenagers sleep late, and the time of day when most people die (which is also the time most people are born), etc, etc.

Secrets of the Body Clock with Terry Wogan

Sir Terry Wogan discovers why timing is everything as he explores the human body clock, a ticking timepiece that lives in our brain and controls the daily rhythms of our body with the outside world. Many people are completely unaware of it, and have no idea there is an optimum time for everything - from driving safely to exercising, and even visiting the dentist.

http://www.bbc.co.uk/iplayer/episode/b0 ... rry_Wogan/

Duration 40 minutes: Available until 11:14PM Tue, 14 Jan 2014

I learned a lot, even though working shifts in various jobs had already taught me a little about the subject.
 

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PeniG said:
The 25-hour circadian rhythm permits the body to adjust gradually to gradual changes in sunrise and sunset throughout the year and as you move around the landscape from the winter hunting grounds to the summer gathering grounds.
Wouldn't that help when the days are getting longer, but hinder when the days are getting shorter?
 

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Newly published survey research indicates there are 6 primary chronotypes (circadian styles or patterns) evident in modern humans. In other words, it's not as simple as early birds versus night owls.
There Are 6 Human Chronotypes, Not Just Morning Larks And Night Owls, Study Says

Some people are morning larks. Others are night owls. But not everybody falls neatly into those two categories, scientists say – and a new study suggests there are actually multiple distinct 'chronotypes' that define people's wakefulness and rest.

Chronotypes are the behavioural manifestations of the circadian rhythms we experience throughout the day and the night. In a sense, they're your internal body clock, helping to determine whether you're a morning person or a night person.

Waking life, however, isn't perhaps quite as binary as those stereotypes might suggest, and at least some evidence suggests alternative chronotypes also exist beyond early birds and night owls.

"The research of individual chronobiological and chronopsychological differences is predominantly focused on the morning and evening chronotypes," explains human physiology researcher Dmitry S. Sveshnikov from RUDN University in Russia.

"However, recent studies suggest that the existing classification needs to be reconsidered and expanded."

In their new study, Sveshnikov and fellow researchers surveyed almost 2,300 participants, most of whom were university students. The participants were asked to self-assess their own chronotype based on a range of six possible types identified in previous studies conducted by some of the same researchers. ...

FULL STORY: https://www.sciencealert.com/scient...otypes-not-just-morning-people-and-night-owls
 

EnolaGaia

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Here are the bibliographic details and abstract from the published report on the chronotype study. The full report can be accessed at the link below.

Single-Item Chronotyping (SIC), a method to self-assess diurnal types by using 6 simple charts,
Arcady A. Putilov, Dmitry S. Sveshnikov, Alexandra N. Puchkova, Vladimir B. Dorokhov, Zarina B. Bakaeva, Elena B. Yakunina, Yuri P. Starshinov, Vladimir I. Torshin, Nikolay N. Alipov, Olga V. Sergeeva, Elena A. Trutneva, Michael M. Lapkin, Zhanna N. Lopatskaya, Roman O. Budkevich, Elena V. Budkevich, Marina P. Dyakovich, Olga G. Donskaya, Juri M. Plusnin, Bérénice Delwiche, Clara Colomb, Daniel Neu, Olivier Mairesse
Personality and Individual Differences, Volume 168, 2021,110353
https://doi.org/10.1016/j.paid.2020.110353

Abstract
Research on individual differences in the fields of chronobiology and chronopsychology mostly focuses on two – morning and evening – chronotypes. However, recent developments in these fields pointed at a possibility to extend chronotypology beyond just two chronotypes. We examined this possibility by implementing the Single-Item Chronotyping (SIC) as a method for self-identification of chronotype among six simple chart options illustrating the daily change in alertness level. Of 2283 survey participants, 2176 (95%) chose one of these options. Only 13% vs. 24% chose morning vs. evening type (a fall vs. a rise of alertness from morning to evening), while the majority of participants chose four other types (with a peak vs. a dip of alertness in the afternoon and with permanently high vs. low alertness levels throughout the day, 15% vs. 18% and 9% vs. 16%, respectively). The same 6 patterns of diurnal variation in sleepiness were yielded by principal component analysis of sleepiness curves. Six chronotypes were also validated against the assessments of sleep timing, excessive daytime sleepiness, and abilities to wake or sleep on demand at different times of the day. We concluded that the study results supported the feasibility of classification with the 6 options provided by the SIC.

FULL REPORT:
https://www.sciencedirect.com/science/article/pii/S0191886920305444?via=ihub
 

EnolaGaia

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Newly published research indicates our immune systems are influenced by our circadian rhythms ...
Daily Rhythms May Impact Our Ability to Fight Disease – Immune System Killer Cells Controlled by Circadian Rhythms

An analysis of an exhaustive dataset on cells essential to the mammalian immune system shows that our ability to fight disease may rely more heavily on daily circadian cycles than previously assumed.

Malfunctions in circadian rhythms, the process that keeps our bodies in tune with the day/night cycles, are increasingly associated with diabetes, cancer, Alzheimer’s, and many other diseases. An investigation published today in Genome Research shows that the activity of macrophages — cells within us that seek and destroy intruders like bacteria — may time daily changes in their responses to pathogens and stress through the circadian control of metabolism. ...

FULL STORY:
https://scitechdaily.com/daily-rhyt...killer-cells-controlled-by-circadian-rhythms/

PUBLISHED REPORT:
Post transcriptional Circadian regulation in Macrophages Organizes Temporally Distinct Immunometabolic States
Emily J. Collins, Mariana P. Cervantes-Silva, George A. Timmons, James R. O’Siorain, Annie M. Curtis and Jennifer M. Hurley
12 January 2021, Genome Research.
doi: 10.1101/gr.263814.120

https://genome.cshlp.org/content/early/2021/01/06/gr.263814.120
 
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