A practical reference on circadian rhythm: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-16. Anything still debated is marked as such rather than presented as settled.
Analytical identification and purity assessment often use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Liquid chromatography–tandem mass spectrometry is used to detect and quantify SR9009 in biological matrices, including urine and blood, for anti-doping or pharmacokinetic studies. Nuclear magnetic resonance spectroscopy can confirm molecular structure. Stability depends on form and storage: the solid is generally more stable than solutions, and repeated freeze–thaw cycles may degrade samples. Purity is typically reported as a percentage from a certificate of analysis.
Regulatory treatment of SR9009 varies by country and context. It is not approved as a therapeutic drug by agencies such as the United States Food and Drug Administration or the European Medicines Agency. Sports authorities list it as a prohibited substance; the World Anti-Doping Agency classifies it among hormone and metabolic modulators. Legal status for personal possession or sale differs across jurisdictions, and some countries may restrict it under analog or research chemical laws. Buyers who seek verified material often rely on independent laboratory testing because online product labels may not match contents.
SR9009 is not approved as a medicine by major regulatory agencies. It is commonly sold as a research chemical, a category that may fall outside customary drug approval and quality rules. In sports, the World Anti-Doping Agency lists SR9009 as a prohibited substance. Athletes who use it can face sanctions if it is detected in a sample. Legal status varies by country, and importation may be restricted. Enforcement practices differ across borders.
Detection of SR9009 in biological samples usually employs liquid chromatography coupled with tandem mass spectrometry. This method can identify the parent compound and sometimes metabolites in urine or blood. Because exposure can be low and clearance may be rapid, sample timing and limits of detection matter. Laboratories validate assays for sensitivity and specificity. Results are interpreted alongside chain-of-custody and quality-control records. Urine is the common matrix for anti-doping analysis, while blood may be used in research settings.
Handling recommendations for SR9009 in a laboratory setting include storing the solid at low temperature, protected from light and moisture. The compound is often dissolved in dimethyl sulfoxide or ethanol for experiments. Solutions should be prepared with appropriate personal protective equipment and disposed of according to local rules. Stability data for long-term storage are limited, so stock solutions are typically kept cold and used within defined periods. Records of preparation date and concentration support reproducibility.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Common supplier description |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water |
| Typical storage | −20 °C, desiccated, dark | For research samples |
| Analytical method | LC-MS/MS | Used for detection and quantification |
| Regulatory status | Prohibited in sport | WADA metabolic modulator class |
SR9009 is a synthetic small molecule developed as an agonist of the nuclear receptors REV-ERBα (NR1D1) and REV-ERBβ (NR1D2). These receptors help regulate circadian rhythms and metabolic gene expression. In cell and animal studies, SR9009 alters transcription of genes involved in lipid metabolism, inflammation, and mitochondrial function. It is not an approved medicine, and its pharmacological profile in humans remains largely uncharacterized. The compound is frequently discussed in the context of circadian biology and metabolic research rather than clinical use.
Preclinical reports have linked SR9009 to improved endurance and altered energy expenditure in rodents. Such findings have prompted interest in whether REV-ERB activation can influence skeletal muscle metabolism. However, the reported effects depend on dose, route, and experimental model, and replication across laboratories is limited. Human trials have not established comparable outcomes, so claims about exercise performance remain speculative. The absence of controlled human data is a central limitation in interpreting these observations.
The mechanism of action involves binding to REV-ERB receptors and recruiting corepressor complexes, which represses target gene transcription. This contrasts with many nuclear receptor agonists that activate transcription. Downstream effects may include changes in autophagy, mitochondrial biogenesis, and lipid handling, but the precise pathways remain an active area of study. Whether these molecular events translate into meaningful physiological effects in humans is unresolved. Most evidence comes from cultured cells and rodent models rather than human participants.
At the molecular level, SR9009 binds REV-ERBα and REV-ERBβ and alters their repressive activity on target genes. These nuclear receptors help regulate the circadian clock, lipid synthesis, glucose metabolism, and inflammatory pathways. By changing transcription, the compound can shift the timing or magnitude of downstream metabolic processes in model systems. It does not act through androgen receptors or adenosine receptors, which distinguishes it from several substances sold for athletic performance. Whether the same transcriptional changes occur in humans at tolerable exposures remains an open question because controlled human studies are lacking.
Preclinical reports describe effects on exercise endurance, mitochondrial content, and lipid profiles in rodents, but these findings come from specific experimental conditions. Many studies use high doses or delivery methods that may not translate directly to human use. SR9009 has been reported to have low oral bioavailability and a short half-life, which complicates interpretation of oral dosing studies. It is not established as safe or effective for any indication. Literature discussions often separate its pharmacological mechanism from unverified claims made in fitness and supplement markets.
Many of the early X-ray and radioactivity researchers went down in history as "martyrs for science." In her article, The Miracle and the Martyrs, Sarah Zobel of the University of Vermont tells of a 1920 banquet held to honor many of the pioneers of X-rays. Chicken was served for dinner: "Shortly after the meal was served, it could be seen that some of the participants were unable to enjoy the meal. After years of working with X-rays, many of the participants had lost fingers or hands due to radiation exposure and were unable to cut the meat themselves". The first American to die from radiation exposure was Clarence Madison Dally (1845-1904), an assistant to Thomas Alva Edison (1847-1931). Edison began studying X-rays almost immediately after Röntgen's discovery and delegated the task to Dally. Over time, Dally underwent more than 100 skin operations due to radiation damage. Eventually, both of his arms had to be amputated. His death led Edison to abandon all further X-ray research in 1904. One of the pioneers was the Austrian Gustav Kaiser (1871-1954), who in 1896 succeeded in photographing a double toe with an exposure time of 1½-2 hours. Due to the limited knowledge at the time, he also suffered severe radiation damage to his hands, losing several fingers and his right metacarpal. His work was the basis for, among other things, the construction of lead rubber aprons. Heinrich Albers-Schönberg (1865-1921), the world's first professor of radiology, recommended gonadal protection for testicles and ovaries in 1903.
== Challenges == Despite the considerable investments made by several companies, proteins chips have yet to flood the market. Manufacturers have found that proteins are actually quite difficult to handle. Production of reliable, consistent, high-throughput proteins that are correctly folded and functional is fraught with difficulties as they often result in low-yield of proteins due to decreased solubility and formation of inclusion bodies. A protein chip requires a lot more steps in its creation than does a DNA chip. There are a number of approaches to this problem which differ fundamentally according to whether the proteins are immobilised through non-specific, poorly defined interactions, or through a specific set of known interactions. The former approach is attractive in its simplicity and is compatible with purified proteins derived from native or recombinant sources but suffers from a number of risks. Most notable amongst these relate to the uncontrolled nature of the interactions between each protein and the surface; at best, this might give rise to a heterogeneous population of proteins in which active sites are sometimes occluded by the surface; at worst, it might destroy activity altogether due to partial or complete surface-mediated unfolding of the immobilised protein.
Cortisol follows a circadian rhythm, and to accurately measure cortisol levels is best to test four times per day through saliva. An individual may have normal total cortisol but have a lower than normal level during a certain period of the day and a higher than normal level during a different period. Therefore, some scholars question the clinical utility of cortisol measurement. Cortisol is lipophilic, and is transported bound to transcortin (also known as corticosteroid-binding globulin (CBG)) and albumin, while only a small part of the total serum cortisol is unbound and has biological activity. This binding of cortisol to transcortin is accomplished through hydrophobic interactions in which cortisol binds in a 1:1 ratio. Serum cortisol assays measures total cortisol, and its results may be misleading for patients with altered serum protein concentrations. The salivary cortisol test avoids this problem because only free cortisol can pass through the blood-saliva barrier. Transcortin particles are too large to pass through this barrier, that consists of epithelial cell layers of the oral mucosa and salivary glands. Cortisol may be incorporated into hair from blood, sweat, and sebum. A 3 centimeter segment of scalp hair can represent 3 months of hair growth, although growth rates can vary in different regions of the scalp. Cortisol in hair is a reliable indicator of chronic cortisol exposure. Automated immunoassays lack specificity and show significant cross-reactivity due to interactions with structural analogs of cortisol, and show differences between assays.
Sources: en.wikipedia.org
== Metabolism == 5-HTP is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of vitamin B6. This reaction occurs both in nervous tissue and in the liver. 5-HTP crosses the blood–brain barrier, while 5-HT does not. Excess 5-HTP, especially when administered with vitamin B6, is thought to be metabolized and excreted.
Phosphorus is used in trace amounts as a dopant for n-type semiconductors. The commercial use of gallium compounds is dominated by semiconductor applications – in integrated circuits, cell phones, laser diodes, light-emitting diodes, photodetectors, and solar cells. Selenium is used in the production of solar cells and in high-energy surge protectors. Boron, silicon, germanium, antimony, and tellurium, as well as heavier metals and metalloids such as Sm, Hg, Tl, Pb, Bi, and Se, can be found in topological insulators. These are alloys or compounds which, at ultracold temperatures or room temperature (depending on their composition), are metallic conductors on their surfaces but insulators through their interiors. Cadmium arsenide Cd3As2, at about 1 K, is a Dirac-semimetal – a bulk electronic analogue of graphene – in which electrons travel effectively as massless particles. These two classes of material are thought to have potential quantum computing applications.
== Early life == Heppell participated in the Auskick program at Leongatha. He began playing football with Leongatha Football Club, and played for Gippsland Power in the TAC Cup for the 2009 and 2010 seasons. Named as Gippsland's captain for the 2010 season, Heppell also played for the Victorian Country side at the 2010 AFL Under 18 Championships, where he was named in the All-Australian team. At 189 cm, he played as a "line-breaking defender" for the first half of the 2010 season, before moving into the midfield for the second half of the season. Heppell finished strongly in the Morrish Medal count, which is awarded to the best and fairest player in the TAC Cup regular season, eventually tying for the award with Jackson Sketcher of the Sandringham Dragons, after achieving the maximum votes possible from rounds 13 to 17. Despite finishing the regular season in sixth place on the ladder, both Gippsland and Heppell had a good finals series. He accumulated 36 disposals in an elimination final victory and was named best on ground in the preliminary final win to qualify for the TAC Cup Grand Final. In a stark contrast to the rest of his season, Heppell had a relatively poor game in the grand final, gathering only 20 touches, as the Power were outclassed by the Calder Cannons by 56 points.
Sources: en.wikipedia.org
==== Distribution ==== Pregabalin crosses the blood–brain barrier and enters the central nervous system. However, due to its low lipophilicity, pregabalin requires active transport across the blood–brain barrier. The LAT1 is highly expressed at the blood–brain barrier and transports pregabalin across into the brain. Pregabalin has been shown to cross the placenta in rats and is present in the milk of lactating rats. In humans, the volume of distribution of an orally administered dose of pregabalin is approximately 0.56 L/kg. Pregabalin is not significantly bound to plasma proteins (<1%).
Trabectedin, sold under the brand name Yondelis, is an antitumor chemotherapy medication for the treatment of advanced soft-tissue sarcoma and ovarian cancer. The most common adverse reactions include nausea, fatigue, vomiting, constipation, decreased appetite, diarrhea, peripheral edema, dyspnea, and headache. It is sold by Pharma Mar S.A. and Johnson and Johnson. It is approved for use in the European Union, Russia, South Korea and the United States. The European Commission and the U.S. Food and Drug Administration (FDA) granted orphan drug status to trabectedin for soft-tissue sarcomas and ovarian cancer. It was originally discovered in the sea squirt Ecteinascidia turbinata. Because natural yields are extremely low, its supply is based on a semisynthetic process starting from a chemical obtained from the bacterium Pseudomonas fluorescens.
The evidence that arsenic may be a beneficial nutrient at trace levels below the background to which living organisms are normally exposed has been reviewed. Some organoarsenic compounds found in nature are arsenobetaine and arsenocholine, both being found in many marine organisms. Some As-containing nucleosides (sugar derivatives) are also known. Several of these organoarsenic compounds arise via methylation processes. For example, the mold Scopulariopsis brevicaulis produces significant amounts of trimethylarsine if inorganic arsenic is present. The organic compound arsenobetaine is found in some marine foods such as fish and algae, and also in mushrooms in larger concentrations. In clean environments, the edible mushroom species Cyanoboletus pulverulentus hyperaccumulates arsenic compounds in concentrations reaching 1,300 mg/kg (dry weight). A very unusual set of organoarsenic compounds was found in deer truffles (Elaphomyces spp.). The average person's intake is about 10–50 μg/day. Values about 1000 μg are not unusual following consumption of fish or mushrooms; however, there is little danger in eating fish since this arsenic compound is nearly non-toxic.
An immigration stamp is an inked impression in a passport or other travel document, typically made by a rubber stamp upon entering or exiting a territory. Depending on the jurisdiction, a stamp can serve different purposes. For example, in the United Kingdom, an immigration stamp in a passport includes the formal leave to enter granted to a person subject to entry control. In other countries, a stamp activates or acknowledges the continuing leave conferred in the passport bearer's entry clearance. Under the Schengen system, a foreign passport is stamped with a date stamp which does not indicate any duration of stay. This means the person is deemed to have permission to remain for either 3 months or the period shown on their visa, if specified otherwise. Member states of the European Union are not permitted to place a stamp in the passport of a person who is not subject to immigration control. Stamping is prohibited because it imposes a control to which the person is not subject. Passport stamps may occasionally take the form of sticker stamps, such as entry stamps from Japan. Depending on nationality, a visitor may not receive a stamp at all (unless specifically requested), such as an EU or EFTA citizen travelling to an EU or EFTA country, Albania, or North Macedonia. Most countries issue exit stamps in addition to entry stamps. A few countries issue only entry stamps, including Canada, El Salvador, Ireland, Mexico, New Zealand, Singapore, United Kingdom and the United States of America.
Sources: en.wikipedia.org
Legality depends on the country and the intended use. In many places it is sold as a research chemical, but sports and medicine regulations restrict it.
Detection commonly uses liquid chromatography–tandem mass spectrometry. This method can identify the compound in urine or blood at low concentrations.
Typical guidance is −20 °C, dry, and protected from light. Solutions should be aliquoted and limited freeze–thaw cycles should be used.
Its legal status depends on the country and intended use. It is not an approved medicine in major jurisdictions. In sport, it is prohibited by anti-doping rules.