If the two things you can't live without are a dark, even tan and a fast-acting, long-lasting erection, then add Melanotan II to your holiday shopping list. This synthetic peptide hormone, which was developed by a research team at the University of Arizona during the late 1990s, darkens skin pigment and may stimulate erectile activity. And despite continued concern and controversy within the medical community regarding its use, it remains available for sale over the internet in a powdered form that can then be reconstituted for subcutaneous injections.

Differences among groups were analyzed using a one-way analysis of variance combined with the Bonferroni test. The relative intensities of mRNA and protein bands were assayed using Quantity-One software (Bio-Rad Co., Hercules, CA, USA); results were normalized to the mRNA and protein levels of beta-actin. All values were expressed as mean ± standard deviation. Differences were considered significant at p < 0.05.

The promise of repairing sun parched aging skin is alluring, especially if damage control may be attained by applying a substance that is abundant in our body. Thymosin beta 4 (Tb4), a molecule that accelerates wound healing in animals and cultured cells, "may be valuable in repairing skin damage caused by sun or even by the wear and tear of aging?" This hopeful message of Tb4's potential to restore damaged human skin was voiced at the 5th International Symposium on Aging Skin, in California (May 2001), by Dr. Allan Goldstein, Chairman of the Biochemistry Department at George Washington University and founder of RegeneRX Biopharmaceuticals. RegeneRX is carrying out preclinical research on Tb4 as a wound healer, in collaboration with scientists at the National Institutes of Health.


Thymosin beta 4 accelerated skin wound healing in a rat model of a full thickness wound where the epithelial layer was destroyed. When Tb4 was applied topically to the wound or injected into the animal, epithelial layer restoration in the wound was increased 42% by day four and 61% by day seven, after treatment, compared to untreated. Furthermore, Tb4 stimulated collagen deposition in the wound and angiogenesis. Tb4 accelerated keratinocyte migration, resulting in the wound contracting by more than 11%, compared to untreated wounds, to close the skin gap in the wound. An analysis of skin sections (histological observations) showed that the Tb4 treated wounds healed faster than the untreated. Proof of accelerated cell migration was also seen in vitro, where Tb4 increased keratinocyte migration two to three fold, within four to five hours after treatment, compared to untreated keratinocytes.
Hi Ben..my question is this, I have a 9 year old german shepard..his back end is all of a sudden weak, where he will fall over,like he can’t hold himself up, I can see extreme weaknes inhis hide quarter.The vet has taken many x-rays and blood work, but all comes back perfect.Do you think this pepetide would help my dog?..he is 101 pounds, extremely strong, Walking is his issue, he can run like the wind, then he can fall over.Any help would be greatly appreciated.

With the TB-500 it seems that pain was reduced even more in my shoulder and it appears that I recovered much faster from my workouts. I took the TB-500 on rest days. I have two more 1mg doses of TB-500 and I am going to site inject intramuscularly to the shoulder to see what happens. Then I will stop taking both for a month to see how things work out. Hopefully I won’t need them again.
Tβ4 is the major monomeric actin-sequestering peptide in human tissues, and can bind globular actin (G-actin) in a 1:1 ratio and consequently involved in cytoskeletal regulation by inhibiting the polymerization of G-actin into fibrous actin (F-actin) [7]. In addition, Tβ4 is an ubiquitous naturally occurring molecule and is found at concentrations of 1 × 10−5 to 5.6 × 10−1 M in a variety of tissues and cell types, yet, no receptors for the protein have been identified [33]. A recent study suggests that internalization of exogenous Tβ4 is essential for its subsequent cellular functions [34]. Moreover, Tβ4 has been shown to be associated with, wound healing, hair growth, immunomodulation, and angiogenesis [7–9].

Before the treatment, the female mice were largely indifferent to the cries of a distressed baby, and were even known to trample over them. But after an injection of oxytocin, the mice started to respond more like mothers, picking up the mewling pup in their mouths. Froemke, a neuroscientist at New York University's Langone Medical Center in New York City, was monitoring the animals' brains to find out why that happened.
Skin damage and aging are induced to a large extent by free radicals from the sun and environmental pollutants and from oxidants produced during infection and inflammation. Lipid peroxidation of membranes and increased inflammatory substances, such as thromboxanes and leukotriens, add insult to injury. While skin damage accumulates with age, repair processes slow down. Thus, any boost by a molecule that would reduce free radicals and accelerate molecular events in healing has the potential to hasten skin repair. Tb4 has such healing qualities.

The logic behind this trend is that creating tanned skin (by increasing melanin) with minimal to no sun exposure could protect individuals from skin damage, and even potentially lower melanoma risk. More melanin means more protection from UV radiation, and therefore a healthier (and conveniently, deeper) complexion. In this sense, there is perhaps a kernel of truth to the idea of the “healthy glow”.
At SelfHacked, it’s our goal to offer our readers all the tools possible to get optimally healthy. When I was struggling with chronic health issues I felt stuck because I didn’t have any tools to help me get better. I had to spend literally thousands of hours trying to read through studies on pubmed to figure out how the body worked and how to fix it.
Research in the early 1960s showed that in rats, administration of α-MSH caused sexual arousal, and work on this continued in many labs up through the 1980s, when scientists at University of Arizona began attempting to develop α-MSH and analogs as potential sunless tanning agents, and synthesized and tested several analogs, including melanotan-I and melanotan II.[6][9]
To evaluate the indirect effect of Tβ4 peptide on RANKL-induced osteoclastogenesis, mouse BMMs were incubated with RANKL and CM, prepared from HPDLCs treated with H2O2 and different concentrations of Tβ4, and allowed to differentiate into osteoclasts. As shown in Fig 6, Tβ4 peptide dose-dependently decreased the number of osteoclasts and TRAP activity. To determine whether the reduction in osteoclast generation by Tβ4 could be due to effects of Tβ4 peptide on viability of the BMMs, a cytotoxicity assay was performed. The viability of BMMs was not significantly affected by Tβ4 peptide (data not shown).
In December 2010, the delegate made a delegate only decision to include afamelanotide (also known as melanotan I) with a cross-reference to melanocyte stimulating hormone (MSH) for inclusion into the current Poisons Standard. It was noted that afamelanotide should not be confused with a similar substance commonly known as Melanotan-II, which is a cyclic lactam synthetic analogue of α-MSH. It was noted that melanotan-II was under investigation for treating sexual dysfunction, although this has been abandoned due to side effects associated with the immune and cardiovascular systems. Its metabolite, bremelanotide, is under investigation for treating haemorrhagic shock.
Oxytocin (Oxt; /ˌɒksɪˈtoʊsɪn/) is a peptide hormone and neuropeptide. Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary.[3] It plays a role in social bonding, sexual reproduction, and during and after childbirth.[4] Oxytocin is released into the bloodstream as a hormone in response to stretching of the cervix and uterus during labor and with stimulation of the nipples from breastfeeding.[5] This helps with birth, bonding with the baby, and milk production.[5][6] Oxytocin was discovered by Henry Dale in 1906.[7] Its molecular structure was determined in 1952.[8] Oxytocin is also used as a medication to facilitate childbirth.[9][10][11]
Oxytocin was also correlated with the longevity of a relationship. Couples with the highest levels were the ones still together six months later. They were also more attuned to each other than the low-oxytocin couples when Feldman asked them to talk about a shared positive experience. The high-oxytocin couples finished each other’s sentences, laughed together and touched each other more often. Feldman says it’s still not clear whether oxytocin was responsible for the stability of the couple’s bond six months later or if couples who weren’t as connected failed to trigger the oxytocin system.
I’ve tried researching this on my own but haven’t been able to find much. I have Hashimoto’s Thyroiditis & my endocrinologist says I barely have any thyroid left. Would TB-500 help regenerate new thyroid growth & if so where would I inject it?? I plan on taking this along with the BPC-157 (orally) for gut inflammation to see if it can repair leaky gut & digestive issues. Thoughts?

Although Tβ4 contains only 43 amino acids, it appears to have a wide range of regenerative activities and specific sites on the molecule have been shown to mediate these effects (Goldstein & Kleinman, 2015; Sosne, Qiu, Goldstein, & Wheater, 2010). Both chemically synthesized and recombinant forms have shown efficacy for dermal healing in preclinical models and in human patients (Ehrlich & Hazard, 2012; Kim & Kwon, 2014, 2015; Malinda et al., 1999; Philp, Badamchian, et al., 2003; Philp & Kleinman, 2010; Philp et al., 2006; Ti et al., 2015; Treadwell et al., 2012). A dimeric form has been found to accelerate the rate of dermal healing in an animal model more rapidly than that of the parent molecule (Xu et al., 2013). Tβ4 has also shown repair and regenerative activity in a number of other injury models, such as traumatic brain injury, spinal cord injury, stroke, a model of multiple sclerosis, ischemic limbs, and cardiac damage due to ischemia (Bock-Marquette, Saxena, White, Dimaio, & Srivastava, 2004; Cheng, Kuang, Zhang, Ju, & Wang, 2014; Dube, Bollini, Smart, & Riley, 2012; Morris, Chopp, Zhang, Lu, & Zhang, 2010; Morris et al., 2014; Philp & Kleinman, 2010; Postrach et al., 2014; Smart et al., 2007; Sopko et al., 2011; Ti et al., 2015, Wang et al., 2012; Wei, Kim, Li, Wu, & Gupta, 2014; Xiong, Mahmood, Meng, et al., 2011; Zhang, Zhang, Morris, et al., 2009; Zuo et al., 2013). The processes and pathways for Tβ4-mediated repair are similar in these various tissues and support the observed promotion of dermal healing.
For now, Bartz isn’t sure why oxytocin can have such different effects. Her most educated guess is that the hormone triggers a biased trip down memory lane. Under its influence, people are more likely to remember information about their mother that fits with their current attitudes to relationships. If they are anxious, they’re more likely to remember the negative side of their early life. It’s a reasonable enough idea, and one that Bartz intends to test in the future. It will also be good to repeat the study in a larger group – 31 men make for a relatively small study.
For example, when a mother is nursing her baby, that stimulation from the breast is going into the brain and causing those oxytocin neurons to fire and release oxytocin directly into the brain. That's much more powerful than what happens with a nasal spray. So I think that, you know, in the future, we may have these drugs that can, in a very potent way, tap into this oxytocin system to treat many different kinds of disorders.

All of this becomes heavily ironic when you consider that the chemical in question – a hormone called oxytocin – is often billed as the “hormone of love”, and even marketed as “Liquid Trust”. As a new study shows, the reality is much more complicated. Describing oxytocin as the “hormone of love” is like describing a computer as a “writing tool” – it does other things too, some of which aren’t pleasant.
Despite this, Tβ4’s place on the banned-substances list is warranted. It reflects the possibility that the effects of the supplement may manifest as a tangible improvement in athletes. However, any time a journalist flippantly declares it “heals damaged tissue and speeds recovery”, it should be noted that such claims are a harmful distortion of the facts.

Johansson, A., Westberg, L., Sandnabba, K., Jern, P., Salo, B., & Santtila, P. (2012). Associations between oxytocin receptor gene (OXTR) polymorphisms and self-reported aggressive behavior and anger: Interactions with alcohol consumption [Abstract]. Psychoneuroendocrinology 37(9), 1546-56. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/22421562

Nolen, W. A., van de Putte, J. J., Dijken, W. A., Kamp, J. S., Blansjaar, B. A., Kramer, H. J., and Haffmans, J. Treatment strategy in depression. II. MAO inhibitors in depression resistant to cyclic antidepressants: two controlled crossover studies with tranylcypromine versus L-5-hydroxytryptophan and nomifensine. Acta Psychiatr.Scand 1988;78(6):676-683. View abstract.
Melanotan II can be of unknown quality and subject to contamination and stability concerns with use of multi-dose vials. There is no experience with the product other than through unregulated channels. There are health risks from the substance itself and its route of administration – documented in medical literature, case reports as well as reports from NSW PIC.
RegeneRX Biopharmaceuticals is focusing on the commercialization of Tb4 “For the treatment of injured tissue and non-healing wounds, to enable more rapid repair and/or tissue regeneration.” Especially needy are diabetics who suffer from poor blood circulation and loss of sensation of pain that keeps their wounds unnoticed and unattended for days, leading to ulcers that may not heal. Other hard healing wounds are pressure ulcers in patients who are bed ridden and often receive skin grafts as treatment, or reconstructive surgery.
Liver fibrosis, a major characteristic of chronic liver disease, is inappropriate tissue remodeling caused by prolonged parenchymal cell injury and inflammation. During liver injury, hepatic stellate cells (HSCs) undergo transdifferentiation from quiescent HSCs into activated HSCs, which promote the deposition of extracellular matrix proteins, leading to liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is the most abundant member of the highly conserved β-thymosin family and controls cell morphogenesis and motility by regulating the dynamics of the actin cytoskeleton. Tβ4 is known to be involved in various cellular responses, including antiinflammation, wound healing, angiogenesis, and cancer progression. Emerging evidence suggests that Tβ4 is expressed in the liver; however, its biological roles are poorly understood. Herein, we introduce liver fibrogenesis and recent findings regarding the function of Tβ4 in various tissues and discuss the potential role of Tβ4 in liver fibrosis with a special focus on the effects of exogenous and endogenous Tβ4. Recent studies have revealed that activated HSCs express Tβ4 in vivo and in vitro. Treatment with the exogenous Tβ4 peptide inhibits the proliferation and migration of activated HSCs and reduces liver fibrosis, indicating it has an antifibrotic action. Meanwhile, the endogenously expressed Tβ4 in activated HSCs is shown to promote HSCs activation. Although the role of Tβ4 has not been elucidated, it is apparent that Tβ4 is associated with HSC activation. Therefore, understanding the potential roles and regulatory mechanisms of Tβ4 in liver fibrosis may provide a novel treatment for patients.
In November 2008, the UK Medicines and Healthcare products Regulatory Agency (MHRA) warned the public against melanotan use stating it was an unlicensed medicine that may not be safe. As such, it is illegal to market or supply this product in the UK due to its unlicensed nature. Additionally the MHRA warned 18 companies about selling or advertising the product and closed down 72 websites involving melanotan. By 2013, the MHRA had received 18 reports of 74 separate reactions to the products and reactions have involved stomach and heart problems, as well as blood and eye disorders.

Research substantiates Wiebe's anecdotal claims. Melanotan.org, a forum dedicated to the peptide that shut down in 2011, had thousands of regular posters, many of whom have since migrated to other discussion boards. In 2009, a BBC report tracking just six needle exchanges found that hundreds of individuals had visited these exchanges in order to receive syringes for Melanotan II use. A year later, the Norwegian Pharmacy Association disclosed that, in Norway alone, several thousand syringes had been distributed to individuals seeking to inject the peptide. Linn Connie Danielsen, a model and blogger, told the Norwegian newspaper Verdens Gangthat Melanotan II helps ease the stressful impact of extended winter sun deprivation. "A nice tan in the winter is good to see," she said.
Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstance or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.
In the ER, the patient's heart rate was elevated, she was sweaty, and had some muscle spasms. The physician in the ER called Poison Control for guidance. Poison Control indicated that a drug interaction between 5-HTP and Zoloft was a likely cause of the patient's symptoms because they were consistent with a rare but serious condition (serotonin syndrome) that occurs when serotonin concentrations in the brain are too high. Poison Control recommended a sedative to decrease the patient's heart rate and improve the other symptoms. 
A: 5-HTP stands for 5-hydroxytryptophan. 5-HTP is classified as a dietary supplement; it is made from the seeds of an African plant, Griffonia simplicfolia. 5-HTP is a metabolite (a metabolic by-product) of the amino acid tryptophan, and it is converted by the body into serotonin, which acts in the brain to sooth a person's mind and comfort one from stress and worry. People are using 5-HTP for a variety of conditions, including weight loss, depression, anxiety, PMS, fibromyalgia, eating disorders, obsessive-compulsive disorder (OCD), and headaches. 5-hydroxytryptophan has not been evaluated by the FDA for safety, effectiveness, or purity. One should follow the dosage recommendations on the particular packages of 5-HTP they purchase. According to one researcher, the suggested dosage range of 5-HTP is between 50 mg and 1,200 mg per day, with the usual range being 100 to 600mg. It is always a good idea to check with one

When practicing deep breathing, focus on a calmer state of mind as you distract yourself from overwhelming thoughts and sensations. Sit in a quiet area and practice the following: Take a slow, deep breath through your nose, allowing both your stomach and chest to rise. Once your stomach is fully expanded, breathe out through your mouth, just as slowly as when you were breathing in.
Froemke's and Tsien's work fits into a broader theory: that one way oxytocin helps social interaction and recognition is by enhancing the brain's response to socially relevant sights, sounds or other stimuli. Young has shown that the hormone helps mice to recognize and pay attention to the smells of other mice7; others found that it promotes people's ability to recognize faces8.
Sexual activity: The relationship between oxytocin and human sexual response is unclear. At least two uncontrolled studies have found increases in plasma oxytocin at orgasm – in both men and women.[103][104] Plasma oxytocin levels are notably increased around the time of self-stimulated orgasm and are still higher than baseline when measured five minutes after self arousal.[103] The authors of one of these studies speculated that oxytocin's effects on muscle contractibility may facilitate sperm and egg transport.[103]
5-HTP is very reliable in increasing serotonin levels. 5-HTP is actually used as a clinical test to judge the potency of drugs that affect serotonin levels (by pairing an experimental drug with 5-HTP to induce 'serotonin syndrome', or serotonin toxicity, one can see how much that drug exacerbates serotonin biosynthesis or bioavailability by seeing how much of a 5-HTP dose is required to induce the syndrome; the lower dose indicative of higher drug potency). This test is known as the 5-HTP induced syndrome test.[8]
Last month, in the article “How To Use BPC-157: A Complete Dummies Guide To Healing The Body Like Wolverine“, I introduced the little-known concept of using BPC-157 peptide self-injections and oral BPC-157 peptide consumption (currently completely legal and not banned by sporting organizations) for everything from rapidly healing leaky gut to fixing tendon, ligament and muscle injuries.
In a study measuring oxytocin serum levels in women before and after sexual stimulation, the author suggests it serves an important role in sexual arousal. This study found genital tract stimulation resulted in increased oxytocin immediately after orgasm.[105] Another study reported increases of oxytocin during sexual arousal could be in response to nipple/areola, genital, and/or genital tract stimulation as confirmed in other mammals.[106] Murphy et al. (1987), studying men, found oxytocin levels were raised throughout sexual arousal with no acute increase at orgasm.[107] A more recent study of men found an increase in plasma oxytocin immediately after orgasm, but only in a portion of their sample that did not reach statistical significance. The authors noted these changes "may simply reflect contractile properties on reproductive tissue".[108]

Mental health is so under-funded in the UK that pills can be used as the quick-fix option. In 2014/15, 57.8million prescriptions for antidepressants or SSRIs are filled out in England alone. You can wait months on a waiting list for cognitive behavioural therapy or to see a psychiatrist, and as you wait, medication is a lifeline. In addition to this mess, pharma giants have stopped looking for the 'next Prozac', cutting funding into new treatments by 70 percent in the last decade. The bottom line is clear: SSRIs, with all their pros and cons, are here to stay.
Increasing trust and reducing fear. In a risky investment game, experimental subjects given nasally administered oxytocin displayed "the highest level of trust" twice as often as the control group. Subjects who were told that they were interacting with a computer showed no such reaction, leading to the conclusion that oxytocin was not merely affecting risk-aversion.[18] Nasally administered oxytocin has also been reported to reduce fear, possibly by inhibiting the amygdala (which is thought to be responsible for fear responses).[19] There is no conclusive evidence for access of oxytocin to the brain through intranasal administration, however.

In 2015 I found my self bed ridden for 8 weeks with an issue all the doctors I had been to we’re unable to diagnose. I discovered, after much research, that what I was suffering from was damaged facia in my left and right gluteus muscles, which left me unable to do anything. I was in excruciating pain and couldn’t do anything except lay in bed on my back. Then my husband found TB 500. Initially I was against using it but after deteriorating to the point of being bed ridden I broke down and ordered some. As soon as I received it my husband injected me in the gluteus muscle. Within 30 minutes I started getting relief from the TB-500, within 8 weeks I was out of bed and the pain was gone! It healed the damaged fascia covering the gluteus. If I had not done this I don’t know where I would be today. For me, TB-500 was a life saver and if I had to I would use it again. I have suffered no side affects then or now.
Traumatic brain injury (TBI) remains a leading cause of mortality and morbidity worldwide. No effective pharmacological treatments are available for TBI because all Phase II/III TBI clinical trials have failed. This highlights a compelling need to develop effective treatments for TBI. Endogenous neurorestoration occurs in the brain after TBI, including angiogenesis, neurogenesis, synaptogenesis, oligodendrogenesis and axonal remodeling, which may be associated with spontaneous functional recovery after TBI. However, the endogenous neurorestoration following TBI is limited. Treatments amplifying these neurorestorative processes may promote functional recovery after TBI. Thymosin beta4 (Tβ4) is the major G-actin-sequestering molecule in eukaryotic cells. In addition, Tβ4 has other properties including anti-apoptosis and anti-inflammation, promotion of angiogenesis, wound healing, stem/progenitor cell differentiation, and cell migration and survival, which provide the scientific foundation for the corneal, dermal, and cardiac wound repair multicenter clinical trials. Here, we describe Tβ4 as a neuroprotective and neurorestorative candidate for treatment of TBI.

For now, Bartz isn’t sure why oxytocin can have such different effects. Her most educated guess is that the hormone triggers a biased trip down memory lane. Under its influence, people are more likely to remember information about their mother that fits with their current attitudes to relationships. If they are anxious, they’re more likely to remember the negative side of their early life. It’s a reasonable enough idea, and one that Bartz intends to test in the future. It will also be good to repeat the study in a larger group – 31 men make for a relatively small study.
Expanding upon the possible anti-panic effects of 5-HTP, one study using 2mg/kg 5-HTP to children (3.2-10.6 years of age) at bedtime for 20 days noted that 5-HTP was asssociated with beneficial response (more than 50% reduction in night terror frequency) of 93.5% of children relative to 28.6% in placebo.[42] Oddly, 6 months after the initial supplementation period the 5-HTP group still reported less sleep terrors (83.9% reporting improvement).[42]
Although Tβ4 contains only 43 amino acids, it appears to have a wide range of regenerative activities and specific sites on the molecule have been shown to mediate these effects (Goldstein & Kleinman, 2015; Sosne, Qiu, Goldstein, & Wheater, 2010). Both chemically synthesized and recombinant forms have shown efficacy for dermal healing in preclinical models and in human patients (Ehrlich & Hazard, 2012; Kim & Kwon, 2014, 2015; Malinda et al., 1999; Philp, Badamchian, et al., 2003; Philp & Kleinman, 2010; Philp et al., 2006; Ti et al., 2015; Treadwell et al., 2012). A dimeric form has been found to accelerate the rate of dermal healing in an animal model more rapidly than that of the parent molecule (Xu et al., 2013). Tβ4 has also shown repair and regenerative activity in a number of other injury models, such as traumatic brain injury, spinal cord injury, stroke, a model of multiple sclerosis, ischemic limbs, and cardiac damage due to ischemia (Bock-Marquette, Saxena, White, Dimaio, & Srivastava, 2004; Cheng, Kuang, Zhang, Ju, & Wang, 2014; Dube, Bollini, Smart, & Riley, 2012; Morris, Chopp, Zhang, Lu, & Zhang, 2010; Morris et al., 2014; Philp & Kleinman, 2010; Postrach et al., 2014; Smart et al., 2007; Sopko et al., 2011; Ti et al., 2015, Wang et al., 2012; Wei, Kim, Li, Wu, & Gupta, 2014; Xiong, Mahmood, Meng, et al., 2011; Zhang, Zhang, Morris, et al., 2009; Zuo et al., 2013). The processes and pathways for Tβ4-mediated repair are similar in these various tissues and support the observed promotion of dermal healing.
Like I said, it’s amazing stuff. And it shouldn’t come as a surprise that it affects that amazing part of your brain so intimately involved in keeping you safe…the amygdala. Remember, trust has a lot to do with survival among social animals who depend on each other for safety and protection. Show someone an untrustworthy face, and the amygdala is one of two areas that become more active than anywhere else in the brain.7 It is apparently programmed for reading trust just as it is for snakes or spiders.
5-HTP helps the body to produce more serotonin. Serotonin is a neurotransmitter that plays a key role in regulating mood and sleep-wake cycles. Healthy levels of serotonin contribute to a positive mood and outlook and also promote restful sleep. Serotonin also plays an important role in many other of the body’s functions, including digestion, appetite, and pain perception.
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