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10

Short answer: yes. Although clearly the infradian changes in steroid hormones in females are quite "obvious", other changes are less evident, but happen nonetheless in males as well as in females. Most of the hormones produced by endocrine organs such as the hypothalamus (a region at the base of the brain) or the hypophisis are not secreted in a continuous ...


10

Short answer The biological master clock is neurologically and genetically hardwired. The biological clock is not affected by learning. Instead, it is constantly entrained mainly by daylight. Background The biological clock is hardwired in the human body and can be traced back to the master clock in the suprachiasmatic nuclei (SCN) of the hypothalamus ...


8

In theory, having a circadian rhythm should help anticipating daily environmental changes (light, temperature etc.) so that the metabolic performance is maximized. In practice, mice chronically exposed to environmental light-dark cycles with a period length dramatically shorter or longer than that of their circadian clock are prone to become obese. ...


8

The bowel movements are influenced by a lot of factors. For example, when you eat a meal it induces a movement in your large intestines, to defecate and clear up space for new food. Also, there is MMC, migrating motor complex, which is responsible for the bowel movements when you are fasting. It causes a flushing effect, which prevents bacteria to ...


7

The fact that urine output (enuresis) and other kidney functions are circadian is well known, just search on pubmed 'circadian urine kidney'. This can be due both to the fact that liquid consumption is less during the night and to the fact that hormones regulating kidney function like aldosterone and plasma angiotensin II are circadian.


7

When you travel to different time zones, your circadian clock will be off (incorrect). The reason your circadian clock will be off is because your body has adapted to the time zone you are from. When you enter a new time zone, your circadian clock will still be functioning on the old the time zone. If the time zone difference is $\pm 12$ hours, this is a ...


6

I found this - Celec et al. (2003) Circatrigintan cycle of salivary testosterone in human male. Biological Rhythm Research 34: 305-315 Conclusion. We believe that this is the first study demonstrating the existence of circatrigintan and circavigintan rhythms of testosterone in human males. Our findings might have implications in human physiology ...


6

The question piqued my interest, but after hunting through the literature for a bit, I hadn't found any direct answers. Then I went back and read the mouse study you cited a bit more carefully. The mouse study only made a reference to mice being affected at 4 lux, ~100x more sensitive than humans. However, for that number it cited a paper in Science that ...


5

There is indeed a slight weight variation during the day. About 2 - 4 lbs (approx. 1 - 2 kg) [1, 2]. Some causes are: water loss through respiration, perspiration or urination [1]. the relative long period without eating and drinking [2]. metabolic processing of food and drinks during sleep. References: Cindy Banyai. ...


5

Here are some examples: electric oscillators: neural activity cardiac automatism (0.8 ... 1 Hz) mechanical oscillators (as a result of neural activity): heart beats breathing (0.2 ... 0.3 Hz) intestinal peristaltic waves vocal chords activity (up to a few kHz) muscular spasm (pathological) chemical oscillators: insulin variation in concordance with ...


5

I'm interested in learning what influences the desire to go to bed at a particular time? What influences the getting out of bed times? It is the circadian rhythm. Circadian rhythm is mediated by the suprachiasmatic nucleus of hypothalamus, which gets afferent nerves from optic nerve. So, the circadian rhythm is mediated by light. Initiation of the ...


5

The real answer is probably more than you want, but its easy to do better than the list above. I took a look through GEO for human circadian expression data and surprisingly I only found 2. Looking at GSE2703 - the rhesus circadian expression experiment, they have shown 355 genes that are rhythmically expressed. This is not a great experiment because ...


4

Yes, absolutely. A major focus of understanding obesity, diabetes and other metabolic disorders are targeted to understanding the circadian (and other cyclical nature) systems in neurobiology and endocrinology. I can speak within the study of diabetes, there is an observed diabetic "dawn effect" in which there is an early morning (dawn) spike in blood ...


4

Veritasium created an excellent video just on this topic, which I would recommend watching, but will summarize here. A common misconception is that we loose weight when we digest food or burn calories. Keep in mind that that broken down food and those calories* aren't "going anywhere", so technically you shouldn't loose any mass (unless you get rid of the ...


4

The nature of time has been discussed for millenia. We don't know exactly why or where time perception exists, but we do have some information on how it is perceived. The circadian rhythm is basically in place to help us sleep, wake and perform tasks in a 24 hour cycle of light. Robbed of light, and the melatonin it's absence produces, the rhythm shifts ...


3

A research paper that recently came out suggests that deep-sea life does have a circadian rhythm, but it is regulated much differently than it is by us surface dwellers. We see light, we eat and digest, and the suprachiasmatic nucleus in the brain (our "biological" clock) keeps track of it and eventually establishes a rhythm of the circadian variety. Most ...


3

Adenosine causes humans to become sleepy. But how ? During day time we consume food which is broken down into glucose. This glucose is broken down by "Glycolysis" in cell's cytoplasm during which ATP is produced. This produced ATP is is then used by body as an energy supplier. ATP breaks down into ADP and then AMP with the release of energy which our body ...


3

The situation is quite complex, and there are certain things that we do not fully understand, but I will try to give you an explanation. First of all, at the cellular level, you have the genetic components of the circadian clock, the clock genes and their protein products. You can divide clock proteins into positive and negative regulators: the positive ...


3

(too long to be a comment) You may be interested in http://en.wikipedia.org/wiki/Phase_response_curve. This graph shows how the body's circadian rhythm normally works: http://en.wikipedia.org/wiki/File:Body_Temp_Variation.png. Body temperature decreases during the night (apparently due to more melatonin production. I conjecture that the proposed schedule ...


3

I'm not aware of any study testing this hypothesis. I would surmise that adverse health effects are likely because the circadian clock operates on a 24-hour time frame, and because lack of sleep for ~40 hours every second day will alter hormone, cytokine and other measures to levels not normally seen in 8-hour sleep/16-hour wake cycle.


3

Yes, the human body has thermoreceptors that "sense" the current temperature, but these merely help with regulation--you know, shivering to raise internal body temperature and sweating to cool via evaporation. The hypothalamus is primarily responsible for making sure that the circadian rhythm itinerary is adhered to reasonably well. So no, if the ...


3

Humans and many other organisms have a circadian clock, a biological system that oscillates every 24 hours (but is also sensitive to external stimuli). There are many components to the human circadian clock that are not known. On the molecular level, gene regulation, post-transcriptional and post-translational modification are all implicated. There is also ...


2

Found a few samples here: http://ars.els-cdn.com/content/image/1-s2.0-S0024320503008142-gr2.gif this shows the nocturnal melatonin peak, which is apparently very important for well being


2

The main effect, of vitamin B6, is neurological, becouse moderate variations in the intracellular concentration of pyridoxal 5'-phosphate (PLP), the biologically active form of vitamin B6, can have pronounced modulatory effects on steroid-induced gene expression. So you cannot get the effect of stress hormones. Also neurological damage has been reported ...


2

I would suggest a couple of papers Circadian rhythms in urinary functions: possible roles of circadian clocks? - Noh et al., Int Neurourol J., 2011 Circadian regulation of renal function - Firsov and Bonny, 2010 Neural regulation of the circadian vasopressin rhythm in cerebrospinal fluid: a pre-eminent role for the suprachiasmatic nuclei - Schwartz and ...


2

The short answer is that it is because the reaction chains dispensing time and enzymes doing those reactions have evolved to negate the impact of environmental factors. The true answer is that the plant clocks do gradually lose sync with 24h cycle when put in stable lighting conditions and move to some more-less random characteristic frequency of their ...


2

I found a recent PLoS article that said that none of hypochondriasis, depression, hysteria, psychopathic deviate, masculinity-femininity, psychasthenia, schizophrenia, or social intraversion (on the MMPI-2) "were associated with any melatonin parameter." However, it does appear that "increases scores of Hypomania and Paranoia were associated with a shorter ...


2

For circadian rhythm, the gold standard is melatonin secretion (blood or saliva). Also, core body temperature. see: Circadian temperature and melatonin rhythms, sleep, and neurobehavioral function in humans living on a 20-h day James K. Wyatt , Angela Ritz-De Cecco , Charles A. Czeisler , Derk-Jan Dijk American Journal of Physiology - Regulatory, ...


2

Wikipedia gives a very good explanation of this, on the page for the suprachiasmatic nucleus. For example, in the fruitfly Drosophila, the cellular circadian rhythm in neurons is controlled by two interlocked feedback loops. In the first loop, the bHLH transcription factors clock (CLK) and cycle (CYC) drive the transcription of their own ...


2

It depends on how different. Day length affects more than just how long the periods of light and dark are. Let's assume a very slow rotation, and a very long day, maybe 1 month light, 1 month dark. The light side would get much warmer while the dark side would get much cooler. At the border between light and dark sides, you'd expect to see powerful storms as ...



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