What Is Serotonin and How Does It Regulate Our Body?

Published on: 06 Jan 2021

Each time you feel a burst of joy, excitement, or satisfaction, there’s a network of nerve cells communicating within your brain that can take some credit for it. Although there are many more processes involved in your general feeling of happiness, some brain chemicals also work hard to make it possible. One of such chemicals is serotonin.

What is serotonin? This brain chemical is largely responsible for boosting your mood and promoting overall well-being in many ways. Here’s what you need to know about this happy chemical and the complex role it plays in your body.

What Is Serotonin?

Serotonin is a neurotransmitter — one of the chemical messengers in the brain that sends messages through your nervous system to different parts of your body in order to control communication between them. Serotonin in the brain is responsible for regulating your mood and memory function, but it also helps with sleep, sexual function, appetite, temperature regulation, and social behavior among other things.

Studies show that the brain’s serotonin system differs slightly between men and women. While men’s serotonin levels are a little higher than women’s, research also shows that women have lower levels of the protein that transports serotonin back to the neurons that secrete it. Experts believe that this may be one reason why women are more prone to depression than men.

How is serotonin made?

Serotonin is manufactured by the brain from the essential amino acid l-tryptophan. Cells that make serotonin combine tryptophan with tryptophan hydroxylase, a chemical reactor, to form 5-hydroxytryptamine — what you and I know as serotonin.  

Although this neurotransmitter is produced in the brain and performs most of its functions there, about 90 percent of your serotonin supply can be found in your gut. Most of the body’s serotonin supply is found in the intestines, and is required by the digestive system to support the healthy breakdown of food.

What is serotonin’s role in digestion?

This chemical joins with receptors in the muscle lining of the gut, to enhance movement of the food you eat through your intestines. When you eat something harmful or unpleasant, your gut reacts by producing an extra dose of serotonin. This moves up the offensive food or substance, helping you get it out of your body fast.

What is the difference between serotonin vs. dopamine?

Serotonin and dopamine are both important neurotransmitters that promote communication between brain cells. They are sometimes called the “happy hormones” because of their function as mood and emotion regulators. An imbalance in dopamine or serotonin levels is also involved in certain mental health conditions like depression.

Since these two chemicals share several similarities, what is serotonin’s distinguishing feature? The main function of serotonin is a little different from dopamine’s function — while dopamine makes you feel pleasure and happiness after engaging in a particular activity, serotonin brings feelings of happiness by stabilizing your mood. Dopamine is also mainly concerned with controlling movement, while serotonin focuses on sleep and digestive function.

How Does Serotonin Regulate Body Function?

Neurotransmitters are involved in a lot of things your body does on a daily basis. In addition to digestion and mood regulation, what is serotonin’s role in terms of body function?

Sleep

Research shows that the time of day can affect your serotonin levels as can how well you sleep, as well as the amount of sleep you get. Melatonin — the hormone responsible for regulating your sleep cycle — is produced from serotonin in the pineal gland of the brain, so an excess or a deficiency of serotonin can affect the quality of your sleep.

Sleeping, however, isn’t limited to serotonin alone. Other brain chemicals like dopamine are also involved in the process.

Blood clotting

The excess serotonin that’s not used up in the gut goes into the bloodstream, where it’s quickly taken up by platelets — the smallest of our blood cells that work to prevent bleeding. These tiny blood cells store up the serotonin and release some of it to help heal cuts, bruises, and other kinds of tissue damage.

When you have higher serotonin levels, the arterioles — small-diameter blood vessels in your circulatory system — become narrow. As they reduce in size, blood flow slows down. This process is key to the function of blood clotting, which is also an important step in healing wounds.

Bone density

What is serotonin’s role in the strength of your bones? Studies show that higher serotonin levels in the gut may be linked to low bone density and other conditions such as osteoporosis.

Research has also shown that a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) are linked to a decrease in bone mineral density, and could make one more susceptible to fractures.

Sexual function

Serotonin doesn’t just influence your mood, it also affects the intensity of your sexual urges, and how often you feel them. The neurotransmitter dopamine also controls the brain’s pleasure and reward system, which kicks in during sex. The relationship between serotonin and dopamine also affects libido.

The influence of serotonin on sexual function can also be observed in terms of selective serotonin reuptake inhibitors (SSRIs). Studies show that this class of antidepressants, which bring higher serotonin levels, also tend to inhibit libido and sexual function.

How Does Serotonin Impact Mental Health?

Apart from its contribution to physiological functions, what is serotonin’s role in mental health?

Many experts believe that an imbalance in serotonin levels may affect an individual’s mood and lead to depression. It’s unclear exactly what causes depression, but there are certain factors that may contribute to it, such as low production of serotonin or an inability of serotonin receptors to receive the serotonin that is made.

Low serotonin levels alone may not cause depression but can lead to other conditions related to mood and sleep. A deficiency of Vitamin B6 and Vitamin D have been linked to low serotonin levels, which affects the production of tryptophan, an essential amino acid involved in the production of serotonin. This shortage in tryptophan can contribute to depression, as well as other conditions like obsessive-compulsive disorder, panic disorder, and anxiety.

Despite the widespread belief that a serotonin deficiency contributes to depression, there is still not enough evidence to prove that serotonin levels are directly correlated with depression or that a deficiency may lead to other mental health conditions. It also remains unclear whether the decrease in serotonin levels is responsible for depression, or if depression causes the serotonin deficiency.

Still, doctors typically prescribe antidepressant medication to improve serotonin levels.These medications may be categorized under the class of selective serotonin reuptake inhibitors (SSRIs) or serotonin and norepinephrine reuptake inhibitors (SNRIs). While these reuptake inhibitors work to reduce symptoms of depression, you should take note that medications that rapidly increase serotonin levels can put you at risk of a severe reaction known as serotonin syndrome.

What Is Serotonin Syndrome?

Many antidepressants are prescribed for treating depression by increasing serotonin levels, but what happens when your medication causes a serotonin overload?

Serotonin syndrome is a rare side effect of selective serotonin reuptake inhibitors (SSRIs) that can occur when two or more medications that affect serotonin levels are used together. For instance, when a doctor prescribes an SSRI medication and it’s taken simultaneously with pain medication like codeine or tramadol, it can result in a serotonin overload.

In some cases, using a single antidepressant can cause serotonin syndrome, but the most common cause is using another type of serotonin-boosting medication, illicit drugs like ecstasy and cocaine, or some herbal supplements.

Symptoms of serotonin syndrome 

Serotonin syndrome can cause a wide range of symptoms, which usually occur within several hours of using the new medication or increasing the dosage of one you’re using. 

Symptoms of serotonin syndrome include confusion, restlessness, dilated pupils, heavy sweating, headache, diarrhea, shivering, goosebumps, and loss of muscle coordination. In severe cases, one may experience high fever, an irregular heartbeat, seizures, or unconsciousness. 

If you suspect that you might have serotonin syndrome after starting a new medication or increasing your dosage, contact your doctor or seek emergency treatment. Usually, you’ll be required to discontinue any medicine that increases serotonin levels.

It’s important to inform your provider of any medication you’re using before adding any new ones, to avoid complications. Recreational drugs such as LSD, ecstasy, and cocaine should also be avoided to prevent serotonin syndrome.

Boosting Serotonin Levels

While you should follow the advice of your doctor or psychiatrist, you don’t necessarily need to rely on prescription antidepressants to improve serotonin levels. Diet can influence tryptophan levels, which also affects your body’s supply of serotonin. Protein-rich foods like eggs, beans, turkey and fish contain high levels of tryptophan, and can help improve your serotonin levels. 

Another way to keep your serotonin in the appropriate range and keep seasonal depression at bay is via exposure to bright light. Light therapy is a way to treat seasonal affective disorder (SAD) and involves sitting near a specialized artificial light throughout the day. Additionally, exercising regularly and incorporating meditation into your day helps boost your mood and relieve stress, which can also increase your serotonin levels.

If you find yourself struggling to regulate your serotonin levels, or if you’re experiencing dips in mood, speaking with a licensed therapist can be a convenient and inexpensive way to discuss your concerns and lay out a personalized plan to improve your overall well-being. With Talkspace, you can speak with an online therapist from the comfort of your home as soon as today. 

Talkspace articles are written by experienced mental health-wellness contributors; they are grounded in scientific research and evidence-based practices. Articles are extensively reviewed by our team of clinical experts (therapists and psychiatrists of various specialties) to ensure content is accurate and on par with current industry standards.

Our goal at Talkspace is to provide the most up-to-date, valuable, and objective information on mental health-related topics in order to help readers make informed decisions.

Articles contain trusted third-party sources that are either directly linked to in the text or listed at the bottom to take readers directly to the source.

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