Serotonin Effects On The Body According To Science

What is Serotonin? How does it affect our body? Why do we need it? And why is it called the ‘happy chemical’? A lot to answer indeed. In this article, we will answer all these questions by explaining what serotonin is, and how it affects our body. 

In short, serotonin is a chemical messenger in our body that is involved in physiological and psychological functions, such as appetite, sleep and mood regulation.

What we need to know about serotonin

Serotonin is an important hormone and neurotransmitter in our body and is a messenger that carries information throughout our body. The chemical is involved in, and is vital for, many different bodily functions such as digestion and wound healing, as well as psychological functions, such as mood regulation. 

These functions are elaborated on in the “what does serotonin do” section. Serotonin is generated in and by our body. To maintain bodily functions, it is important to maintain Serotonin levels. Too high, and too low serotonin levels can cause problems in the body it is then important to maintain serotonin levels in the body.1 

What is serotonin

Serotonin is a chemical that functions as a neurotransmitter and as a hormone in the body. A neurotransmitter is a chemical that upon an impulse, is released by a neuron into a synaptic cleft between two neurons. In this way, the neurotransmitter can transmit information to the next neuron, which results in signal transduction.2 A hormone is also a messenger in the body, but instead of transmitting a signal from one neuron to the next, it is transported through the bloodstream to transduce a signal.1, 3  

In this way, neurotransmission is more local, as the signal is transduced locally from one neuron to the next. Because hormones travel through the body via the blood, they can act more globally and on different tissues and cells throughout the body. Serotonin is a chemical that can act both, as a neurotransmitter (as a messenger between neurons), and as a hormone, ( a messenger transported in the bloodstream). This means that serotonin can act locally, and globally in the body.1  

What does serotonin do

In short, serotonin is a chemical that acts as a messenger in the body and regulates different bodily functions.1 

These functions include: 

  • Mood 
  • Sleep 
  • Nausea 
  • Digestion 
  • Wound healing and blood clotting 
  • Libido 
  • Bone health 
  • Learning and memory 

Effects of serotonin on the body 

Serotonin has many different effects on the body and is crucial for different bodily functions.1  

Mood: Serotonin regulates our mood. It is commonly known as the happy chemical because high serotonin levels lead to improved as well as more stable moods. Low serotonin levels are associated with depression and lower well-being. Thus, to treat depression, medications aim to increase serotonin levels. Low levels of serotonin have also been linked to anxiety and other mood disorders. Concluding, serotonin plays an important role in mood and mood regulation. 

Sleep: Serotonin is also involved in sleep and sleep regulation. Serotonin is needed to create a hormone, called melatonin, which makes us feel tired and regulates our sleep cycle. However, it is not serotonin alone that regulates our sleep and circadian rhythm. Other hormones and neurotransmitters, such as dopamine, are involved as well. Circadian rhythm describes the 24-hour cycle that our bodies and cells follow, which includes the sleep-wake cycle.4 

Thermoregulation: Serotonin has been found to be involved in the temperature regulation of our bodies.5 

Nausea: When high amounts of serotonin are released in the gut, there can be more serotonin than can be digested at the time. This leads to the feeling of nausea because of the signal that is perceived by the brain. 

Appetite: Serotonin is known to decrease appetite while eating. It is linked to the feeling of satiety. 

Digestion: Serotonin is also involved in carbohydrate metabolism. Carbohydrates are a type of sugar and are commonly consumed in a diet. While the exact mechanism is not fully understood, serotonin has been found to increase glycogenolysis, which is what the glucose breakdown in the body is called. This glucose breakdown increases blood glucose levels. (but not fully understood).6

Cardiovascular: Serotonin also affects the cardiovascular system. Serotonin can lead to cardiac vasoconstriction or dilation depending on the targeted vessel. In this way, serotonin is also involved in wound healing and blood clotting.6

Wound healing and blood clotting: Serotonin as a hormone, supports wound healing and blood clotting. It leads small vessels to constrict, which slows down the blood flow in the vessel, through which blood clotting can be achieved more easily. Without this process, wound healing is greatly inhibited. 

Respiration: Serotonin stimulates certain receptors, which increases the respiratory volume and leads to bronchoconstriction, which can ultimately lead to hyperventilation. However, respiration is controlled by many other factors, such as adrenaline, as well. 

Libido: Serotonin is known to affect libido and your desire for sex. High levels of serotonin have been found to decrease libido, whereas low levels are linked to higher libido. This is also why antidepressants that target serotonin can lead to decreased sex drive as a side effect. However, this cannot be generalized, as the effect serotonin has on your libido depends on the activated receptors in your brain, rather than the amount of serotonin alone. Moreover, serotonin is not the only chemical involved. Other neurotransmitters, such as dopamine, influence libido, and sexual desire as well. 

Bone health: Serotonin has been linked to affecting bone health. High levels of serotonin can decrease bone density. Decreased bone density can lead to your bones being more fragile and might lead to osteoporosis. 

Learning and memory: Serotonin is known to be involved in learning and memory. According to research, it improves learning and memory. However, the exact mechanisms have not been fully understood.7 

Overall, it becomes clear that serotonin is involved in many different processes in the brain and the body, and too high and too low levels of serotonin can have negative effects on our body and mind. Therefore, it is an important task of our body to maintain serotonin levels. Low serotonin levels can affect mood and lead to depression, mania, anxiety, etc. If serotonin levels are too high, one might experience serotonin syndrome.1  


  • Nausea
  • Vomiting 
  • Diarrhea 
  • Tremors or muscle twitching 
  • Insomnia (not being able to sleep) 
  • Excessive sweating 
  • Over responsive bodily reflexes

Serotonin syndrome can be fatal. It can be caused by the intake of certain drugs, such as amphetamines. 

Causes of low serotonin level

In general, serotonin levels can be low for two reasons. Either, your body is not producing or receiving enough serotonin. Another way serotonin levels can be low is not by actually low serotonin levels, but by the body not being able to metabolize and use the available serotonin in the body. This could occur when, for example, the serotonin receptors are not functioning properly.7 

Things to do to increase serotonin level

Serotonin levels can be increased in different ways:1  

Diet: Serotonin levels can be increased via the diet. Different foods increase Serotonin levels, such as tofu, pineapple, cheese, salmon, turkey, oats, nuts and seeds. 

Medication: For very low serotonin levels, medication can be used to counterbalance the low levels. This medication includes Selective Serotonin Reuptake Inhibitors (SSRI). This medication increases the amount of serotonin in the synapse. SSRIs are commonly used as antidepressants and are sometimes utilized to target chronic pain. 

Lowering stress levels: Lowering your stress levels can increase serotonin levels as well. 

Spend time outside under the Sun: Sunlight or UV light is needed to synthesize Vitamin D. And Vitamin D activates the synthesis of Serotonin. Hence, sunlight exposure can increase serotonin levels. This is also why many people feel depressed or have lower moods in winter, with lower sun exposure.8   

Exercise: exercise has been found to increase serotonin levels. On top of that, exercise has many other positive effects on your body and improves health. To exercise, you do not need to go to the gym, if that is not to your liking, but simply going on a walk can already help. This could also increase your vitamin D because you spent time outside. Exercise also helps lowering stress levels. 

Supplements: Supplements can also increase serotonin levels. 


Serotonin is a chemical messenger in the brain that acts as a neurotransmitter and hormone. It is commonly referred to as the ‘happy chemical’ as it regulates mood. Serotonin also plays a role in sleep, nausea, digestion, wound healing and blood clotting, libido, bone health, and learning and memory. 

Serotonin levels can be low, if the body is not making enough serotonin, or if the serotonin receptors are not able to receive serotonin. To increase serotonin, one can be in the sun, exercise, lower stress levels, take supplements or make dietary adjustments. 

Overall, Serotonin is an important messenger in our brains and bodies and is involved in many different bodily functions.


  1. Serotonin: what is it, function & levels [Internet]. Cleveland Clinic. [cited 2022 Dec 2]. Available from:
  2. Sheffler ZM, Reddy V, Pillarisetty LS. Physiology, neurotransmitters. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 [cited 2022 Dec 2]. Available from:
  3. Hormones [Internet]. [cited 2022 Dec 2]. Available from:
  4. National institute of general medical sciences [Internet]. National Institute of General Medical Sciences (NIGMS). [cited 2022 Dec 2]. Available from:
  5. Birmes P, Coppin D, Schmitt L, Lauque D. Serotonin syndrome: a brief review. CMAJ [Internet]. 2003 May 27 [cited 2022 Dec 2];168(11):1439–42. Available from:
  6. Sirek A, Sirek OV. Serotonin: a review. Can Med Assoc J [Internet]. 1970 Apr 25 [cited 2022 Dec 2];102(8):846–9. Available from:
  7. Meneses A, Liy-Salmeron G. Serotonin and emotion, learning and memory. Reviews in the Neurosciences [Internet]. 2012 Nov 1 [cited 2022 Dec 2];23(5–6):543–53. Available from:
  8. Patrick RP, Ames BN. Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior. FASEB J. 2015 Jun;29(6):2207–22.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Magdalena Pfaff

Bachelor’s in liberal arts and Sciences – Neuroscience, University College Maastricht

Pursuing a Bachelor in the field of neuroscience with special interest in the connection of body and mind from a biological perspective. She is a motivated and ambitious student who has experience in working in the laboratory, as well as in a therapeutic environment. By combining mental and physical health, she wants to do research and work with patients.

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