Serotonin deficiency has several symptoms, including low mood and low quality sleep. Taking antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) may improve symptoms of serotonin deficiency.

Some researchers have linked serotonin deficiency with depression.

However, if a person’s serotonin levels become too high through the use of serotonin-raising medications such as those for depression, they could develop serotonin syndrome.

In this article, learn about the symptoms of low serotonin, how doctors diagnose and test for low serotonin, and how to increase serotonin levels.

a woman looking sad because she has a serotonin deficiencyShare on Pinterest
A person with serotonin deficiency may experience mood instability.

Serotonin helps regulate a wide range of bodily functions, including orgasm, sleep, bladder and bowel functions, and mood.

Because it plays such an important role in the body, it can be difficult to determine whether low serotonin or something else is causing a specific symptom.

The sections below will look at some potential symptoms associated with low serotonin levels.

Mental health symptoms

Mental health symptoms are among the most common manifestations of low serotonin levels.

Some symptoms to be mindful of include:

  • Mood instability: Serotonin helps regulate mood. People who feel unusually irritable or down for no apparent reason may have low serotonin levels.
  • Depression: Feelings of sadness, hopelessness, and anger, as well as chronic fatigue and thoughts of suicide, may indicate depression.
  • Anxiety: Low serotonin levels may cause anxiety. Some people also develop obsessive-compulsive disorder. This is an anxiety disorder in which a person uses compulsive behavior, such as hand-washing, to deal with intrusive anxious thoughts.
  • Schizophrenia: People with schizophrenia may also have low serotonin. They can experience unusual thoughts that are not grounded in reality and may develop delusions. They might also have hallucinations, such as seeing or hearing things that are not actually there.
  • Memory issues: People with dementia may also have low serotonin levels. Some research has also associated depression with an increased risk of dementia, though it is unclear whether depression causes dementia or is merely a symptom of the same serotonin deficiency that later leads to dementia.
  • Sleep changes: Serotonin helps regulate sleep. People who feel very tired or have difficulty falling or staying asleep may have problems with regulating serotonin. Having excess energy may also mean that there is a problem with serotonin levels.
  • Sexual function: Serotonin helps regulate many aspects of sexual function. Some people with low serotonin levels may experience changes in desire, sexual pleasure, or ability to orgasm.
  • Attention: Serotonin is one of many neurotransmitters that support the ability to concentrate and learn new information. Some people with low serotonin may therefore have trouble with attention, motivation, or learning.
  • Hyperactivity: In some people, low serotonin may cause hyperactivity, excess energy, difficulty sitting still, or difficulty sleeping.

Physical health symptoms

Low serotonin can also affect physical health. Some symptoms include:

  • Somatic symptoms: Some people may experience physical symptoms that are actually rooted in psychological distress or report chronic pain that has no clear physical origin. A 2019 study suggests that disruptions in the serotonin pathway may play a role in these symptoms.
  • Movement issues: People with low serotonin may have trouble with movement, balance, or coordination. Parkinson’s disease, which damages neurons and can cause shaking and other movement problems, also correlates with low serotonin.
  • Premature orgasm or ejaculation: Serotonin increases the length of time it takes to orgasm. Low serotonin may therefore play a role in early ejaculation.
  • Digestive difficulties: Serotonin helps regulate bowel movements. It also triggers food-related nausea.
  • Incontinence: Serotonin supports nerve signaling to the bladder. Low serotonin may cause incontinence or other urinary difficulties, such as not feeling the urge to use the bathroom.
  • Clotting difficulties: Low serotonin levels may impair the wound healing process, as it helps the blood to clot.

Serotonin is a neurotransmitter. This means that it helps carry a nerve signal across a synapse. Serotonin plays a role in many key functions, including memory, sleeping, hunger, digestion, and mood.

Doctors usually diagnose low serotonin based on symptoms, not blood level of serotonin. The symptoms, not the specific levels of serotonin, matter most.

One 2009 study found that SSRIs did not significantly increase serotonin, despite alleviating some depression symptoms. This suggests that SSRIs work by increasing serotonin function rather than serotonin levels in the blood.

Certain antidepressants, including SSRIs, may boost serotonin. However, prescription medications are not the only treatment option for low serotonin.

The following strategies may also help:

  • Psychotherapy: Psychotherapy can help ease the symptoms of a wide range of mental health conditions, including anxiety, depression, insomnia, and trauma. Several studies suggest that therapy may also raise serotonin levels. For example, one 2012 study found that therapy increased serotonin receptors in the brains of people with major depression.
  • Reduce stress: Chronic stress may affect the way the brain processes or produces serotonin, causing a wide range of symptoms.
  • Exposure to natural light: Bright light may help treat seasonal depression, but some research suggests that it may also elevate serotonin levels in people with other types of depression.
  • Exercise: Exercise can help raise serotonin levels. Independently of serotonin levels, exercise is also a viable intervention for depression and anxiety.
  • Diet changes: Eating a healthful diet can support good general health, including the production of serotonin. Tryptophan, which is abundant in foods such as turkey and chickpeas, may act as a weak antidepressant because it helps the body synthesize serotonin.

Serotonin levels vary over time. Sometimes, a person will have no symptoms of depression, or any other serotonin-associated health condition, despite having low levels of serotonin.

If a doctor suspects that serotonin may be the cause of an underlying health condition, they may conduct a range of tests, such as depression surveys or memory tests.

They may also test serotonin levels, though they tend to reserve this for when they suspect a serotonin-secreting tumor.

Serotonin helps the body regulate many functions, including mood.

When serotonin is either too low or too high, a person may develop mental health symptoms.

The physical maladies that low serotonin causes, such as erectile dysfunction and movement disorders, can also impact a person’s mental health.

Healthcare professionals do not fully understand why some people develop serotonin deficiency.

However, some potential causes include:

  • age-related health and brain changes
  • a poor diet
  • chronic stress
  • a lack of exposure to natural light
  • inadequate exercise levels

However, in many cases, there is no clear cause.

A small number of neurons in the central nervous system produce serotonin from the amino acid tryptophan. The amount of tryptophan a person consumes, coupled with the rate at which the body metabolizes it, determines the available levels of tryptophan in their body.

Foods containing tryptophan include:

  • dairy products
  • meat, especially turkey
  • seeds
  • chickpeas

Learn about eight foods that can increase serotonin levels here.

Preliminary research suggests that brain serotonin levels are higher in males than in females, though researchers do not know why.

It is unclear whether sex differences in serotonin levels are natural or if other factors — such as lifestyle, overall health, or exposure to chronic stress — better explain it.

Serotonin deficiency shares its symptoms with a wide range of medical conditions.

It is important to remember that not all people with symptoms of depression or other mental health conditions have low serotonin. Therefore, a person should not assume that they have low serotonin based on symptoms alone.

A person should see a doctor for:

  • depression or anxiety that does not improve with self-care
  • memory loss
  • movement issues
  • any other symptoms of low serotonin, such as changes in sleep, appetite, or bladder control
  • symptoms of low serotonin that do not get better with treatment
  • any side effects associated with low serotonin treatments

Serotonin plays a vital role in most of the body’s functions. For this reason, low serotonin can affect many aspects of well-being.

People who think that they have low serotonin should see a doctor. There are plenty of treatment options available for serotonin-related health concerns.