What Is Serotonin: Roles, Effects, and How to Balance It

• Serotonin is a chemical messenger that transmits signals between nerve cells and the rest of the body.
• Serotonin is sometimes called the body’s natural ​“happy chemical” and can affect mood, digestion, sleep, and more.
• It’s important to have balanced serotonin levels: serotonin deficiency can be linked to symptoms of depression and anxiety, while too high can result in serotonin syndrome, which can be fatal.
• There are ways to naturally increase serotonin in the body and medications that can be prescribed.

Serotonin, also called 5‑hydroxytryptamine (5‑HT), is a chemical messenger that transmits messages between nerve cells in the central nervous system (the brain) and the rest of the body. Like dopamine, serotonin is considered a hormone because it travels through the bloodstream to influence the activity of specific target cells and organs.

Serotonin plays a key role in learning, memory, digestion, and happiness while also regulating body temperature, sleep, sexual behavior, and hunger. A lack of serotonin is thought to play a role in depression, anxiety, mania, and other health conditions.

While serotonin is most commonly associated with the brain, about 90% of serotonin production occurs in the gut (the other 10% in the brain). The intestines release the hormone into the blood, and it’s absorbed by platelets that help carry serotonin where it’s needed.

The body naturally produces serotonin, allowing it to regulate and assist many mental and physical aspects of your health, such as your mood, sleep, digestion, and more.

Mood

Serotonin is most commonly known for its role in regulating mood. Often referred to as one of the body’s ​“feel-good” chemicals, it can help us feel calm and happy at normal levels. Lower levels of serotonin are associated with feelings of depression, anxiety, and mood disorders.

Sleep

Serotonin works with dopamine (a neurotransmitter that can affect mood and coordination) to affect sleep duration and quality. It is also essential for creating melatonin—a hormone that directly impacts the sleep-wake cycle.

Digestion

The vast majority of serotonin production happens in the gut, showcasing its profound impact on the body’s digestive system. Its main roles are to protect the gut and regulate bowel function by speeding up digestion and ridding the body of toxic or irritating foods. It also helps reduce appetite as you eat. The amino acid tryptophan is a necessary component of serotonin production but can only be obtained through food—when a diet is low in tryptophan, it can result in lower serotonin. 

Too much serotonin production in the GI tract before digestion can also cause nausea. When treating nausea, the medications used often block specific serotonin receptors to help alleviate the issue.

Bone Health

Research shows there may be a connection between serotonin and bone health. Overly high levels of serotonin may contribute to bone weakening, which can lead to conditions such as osteoporosis.

Libido

Low serotonin levels can affect your desire for sex. Studies show that higher levels of serotonin paired with lower levels of dopamine can result in lower sexual desire and interest in sex.

Blood Clotting

Platelets release serotonin into the bloodstream to help heal wounds faster. Additionally, serotonin helps narrow blood vessels to slow blood flow, promoting blood clotting, which is essential to the healing process.

While often linked to experiences like grief, trauma, or isolation, anxiety, depression, and other mental health conditions may also be associated with low serotonin levels.

Common symptoms of low serotonin levels include:

• Mood changes
• Sleep issues, like insomnia 
• Digestive issues
• Fatigue
• Memory problems

Low serotonin levels can also contribute to chronic pain and inflammation, as well as migraines and other headaches.

Low serotonin levels result from the body not producing enough serotonin or not effectively using serotonin. This can be caused by a variety of factors, including:

• Genetics: Genetic defects and gene mutations can impact the body’s ability to metabolize or create serotonin.
• Diet: Serotonin production requires the amino acid tryptophan, which can only come from food. Diets low in tryptophan-rich foods may result in lower serotonin levels.
• Lifestyle choices: Not exercising regularly, not getting proper rest, and not getting enough sunlight can all negatively impact serotonin production.
• Medicine: Certain medications, such as selective serotonin reuptake inhibitors (SSRIs), can lower serotonin levels.
• Hormones: Fluctuating estrogen levels, such as those experienced during one’s menstrual cycle, pregnancy, or menopause, may impact serotonin levels and mood.
• Medical conditions: Conditions such as gastrointestinal disorders like irritable bowel syndrome (IBS) or ulcerative colitis may contribute to low serotonin.

Studies have shown that serotonin levels may naturally decrease as people age. The most common explanation is a decline in the function of serotonin transporters and receptors.

Some research has linked Decreases in serotonin levels as we age withe early cognitive decline, and brain scan studies suggest low serotonin levels could be a driving force in conditions such as dementia and Alzheimer’s.

More research is needed to further understand the effects of aging on serotonin. However, it’s important to be aware of any changes in your body or mind so you can monitor symptoms and speak to your doctor if they arise.

There are ways to raise serotonin levels naturally, including dietary and lifestyle changes. There are also ways to readjust serotonin levels in the body through medication if your provider believes your levels are unbalanced.

1: Dietary Changes

While the body naturally produces serotonin, it can only be created by consuming an important and essential amino acid, tryptophan. This amino acid can’t be made on its own in the body and must be obtained by the foods you eat. Eating a diet high in tryptophan-rich foods can help naturally increase serotonin levels.

Foods that are good sources of tryptophan include but are not limited to:

• Fatty fish
• Turkey
• Chicken
• Sweet potatoes
• Dark leafy greens
• Tofu

Consuming probiotic-rich foods can help increase good gut bacteria and positively influence serotonin production as well. Probiotic-rich foods include but are not limited to:

• Sauerkraut
• Kimchi
• Kefir
• Yogurt

Additionally, there are over-the-counter dietary supplements that may also help increase serotonin production, but they should only be taken under the guidance of healthcare professional. Some potential supplements to take include:

• 5‑HTP
• Probiotics
• Pure tryptophan
• SAMe (S‑adenosyl-L-methionine)
• St. John’s wort

2: Lifestyle Changes

• Exercise: Regular physical activity has been proven to boost serotonin levels. Exercise can help people manage depression and other mood disorders by also promoting cardiovascular health, improving strength and endurance, and helping to maintain a healthy weight.
• Sleep: Getting enough sleep and practicing relaxation techniques, such as meditation and yoga, can also help increase serotonin levels.
• Sunlight: Spending time outdoors in the sun can boost serotonin levels by stimulating the body’s circadian rhythm.

3: Medication

Medications don’t directly produce serotonin. Instead, they can modify serotonin receptors and change how your body uses the serotonin it already has. These medications are often used to treat various health conditions, such as depression, anxiety, headaches, and pain relievers, and also happen to increase serotonin. Signs you may need a serotonin boost include:

• Struggling with feelings of depression
• Overwhelming feelings of anxiety
• Struggling with memory and cognitive function, including confusion
• Insomnia

If you begin feeling depressed, anxious, or significant mood changes or experiencing digestive issues, fatigue, or sleep issues, it’s important to speak with your doctor about ways to help and potentially begin a medication like the ones listed below.

Selective Serotonin Reuptake Inhibitors (SSRIs)

SSRIs increase serotonin levels by blocking the reabsorption of serotonin. Examples include:

• Paroxetine (Paxil)
• Fluoxetine (Prozac)
• Citalopram (Celexa)
• Sertraline (Zoloft)
• Escitalopram (Lexapro)

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

SNRIs increase serotonin levels by blocking the reabsorption of both serotonin and norepinephrine. Examples include:

• Venlafaxine (Effexor)
• Duloxetine (Cymbalta)
• Desvenlafaxine (Pristiq)

Monoamine Oxidase Inhibitors (MAOIs)

MAOIs increase serotonin levels by blocking the breakdown of serotonin. Examples include:

• Phenelzine (Nardil)
• Isocarboxazid (Marplan)

Tricyclic antidepressants (TCAs)

TCAs increase serotonin levels by blocking the reabsorption of serotonin and norepinephrine. Examples include:

• Amitriptyline (Elavil)
• Desipramine (Norpramin)
• Doxepin (Zonalon)

It is possible to have too high of a level of serotonin. Too much serotonin can cause serotonin syndrome, a potentially life-threatening condition. Serotonin syndrome typically occurs when the dose on certain medications to manage serotonin levels is raised too high or if multiple medications that impact serotonin are taken at once, such as an antidepressant and certain migraine medications.

Symptoms of serotonin syndrome include:

• Shivering
• Sweating
• Confusion
• Restlessness
• High blood pressure
• Muscle twitches
• Diarrhea

The following symptoms may indicate a severe case of severe serotonin syndrome, which include:

• High fever
• Seizures
• Fainting
• Abnormal heartbeat

If you or someone else is experiencing these symptoms, call 911 immediately.

To ensure proper health, finding ways to keep serotonin levels balanced is important.

If you have low serotonin levels, the best way to increase production naturally is through diet, exercise, getting more sunlight, proper rest, and stress management. These lifestyle changes can help to increase serotonin proactively and may resolve low levels naturally.

If low serotonin is still an issue even after lifestyle changes, antidepressant medications can also be administered to help raise serotonin levels. Some may work better for you than others, so testing different medications (with the encouragement of a healthcare provider) may be required before finding one that is right for you.

Before trying new treatments or supplements, it’s essential to talk to a healthcare provider to ensure safe and effective management of serotonin levels.

Additionally, talking to a therapist can help you deal with the emotional side of low serotonin and figure out how to boost it. A primary care professional can also help you find the right way to balance your serotonin levels to help you feel like yourself again.

Discussing mental health can be challenging—even with more understanding and progress, stigmas surrounding mental health are still prevalent, making it difficult to discuss or recognize when we are experiencing it. This is particularly true for older adults.

If you or a loved one are experiencing issues with mental health, the following resources can help:

• Senior Mental Health Resources (Addiction, Elder Abuse, Anxiety, and More) 
• National Alliance on Mental Health (NAMI)
• Substance Abuse and Mental Health Services Administration (SAMHSA)