Serotonin is a neurotransmitter that is directly involved in the regulation of mood, feelings of relaxation, sleep, and appetite.
When levels of this neurotransmitter are high in the brain, we tend to feel happy, calm, and mentally balanced. Low levels may be linked to anxious thoughts, irritable moods, and restlessness.
Ensuring that adequate levels of the Serotonin neurotransmitter are available in the brain may improve depression, weight loss results, sleep patterns, and sexual dysfunction.
We can improve levels of this neurochemical by eating foods that contain the amino acid L-Tryptophan. This compound is necessary to make Serotonin in the brain. We may also increase levels of the Serotonin neurotransmitter by consuming supplements that contain 5-HTP, which is the direct precursor to Serotonin.



- Increases Serotonin levels in the brain
- Enhances mood and alleviates stress
- Improves sleep and regulates appetite
The Neurotransmitter Serotonin
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When trying to understand the function in the brain of the Serotonin neurotransmitter, the definition and role of a neurotransmitter in the nervous system is a good place to start.
Neurotransmitters are the chemical messengers that send signals between the neurons in the brain.
Our brain is made up of a network of over 80 billion different neurons that communicate with each other using an array of different neurochemicals.
Each neuron has a central nucleus and off of this main body are “axons” and “dendrites” that are used to send and receive messages from other neurons. These axons range from a few millimeters in length to over a meter in length.
Our neurons can communicate with each other at synapses located on these axons and dendrites. These synapses contain receptors to receive chemical messages as well as vesicles to release neurotransmitters.
Many of these neurons have specific roles and only respond to certain types of neurotransmitters. For example, neurons that can respond to the effects of Serotonin are referred to as part of the Serotonergic system.
Serotonin activates these neurons by binding to specific receptor sites on Serotonergic neurons. This neurotransmitter can only bind to receptors that are specific to it. However, there are other chemicals that may also bind to Serotonin receptors and activate similar responses.
Compounds that increase the activation of Serotonin receptors are called “Serotonergic” compounds.
As already described, in the brain and central nervous system, Serotonin acts as a neurotransmitter. However in the rest of the body, Serotonin functions as a hormone. Serotonin in the body primarily is involved in blood coagulation and digestion. Serotonin in the gut facilitates peristalsis (rhythmic contractions of the intestines), aiding in digestion.
Serotonin Neurotransmitter Function in the Brain
Serotonin is an inhibitory neurotransmitter, as opposed to an excitatory neurotransmitter. Excitatory neurotransmitters have a stimulatory effect on neurons. When an excitatory message is received by a neuron, it makes it more likely that the neuron will fire or respond in some way.
Inhibitory neurotransmitters balance these excitatory effects and prevent over-stimulation. If an inhibitory message is received, it makes it less likely that the neuron will fire.
As an inhibitory neurotransmitter, Serotonin balances out the effects of excitatory neurotransmitters which include Dopamine, Norepinephrine, and Epinephrine. These neurochemicals are all associated with states of increased focus, alertness, and mental activation.
While excitatory neurotransmitters can have a positive effect on mental energy and cognitive function, it can be problematic if they are not appropriately balanced. Excess stimulation in the brain can cause restlessness, inability to focus, stress, anxiety, and a lack of clear thoughts.
Serotonin is important for preventing these negative effects and balancing neurochemical signals in the brain. It helps to stabilize mood, improve concentration, promote positive feelings and help the mind relax.
Serotonin is also important at the end of the day for preparing the body for sleep. Melatonin is the main hormone associated with sleep; Melatonin helps to regulate the body’s normal daily sleep/wake cycle (circadian rhythm). Serotonin in the brain is converted into Melatonin in the the pineal gland. Levels of Melatonin begin to rise at dusk, and help the body prepare for sleep.
Signs of Low Serotonin Levels
When levels of the Serotonin neurotransmitter are too low, individuals can experience depression, erratic moods, sleep disturbances, anxiousness, increased appetite, and an inability to concentrate. Some also experience a loss of sex drive.
Serotonin deficiencies can also lead to increased sensations of pain and decreased immune function. In addition, low levels of Serotonin may contribute to migraines and cluster headaches. This compound is also important for controlling the dilation of blood vessels in the scalp, neck, and shoulders.
Ways to Raise Serotonin Levels
In some cases, it may be necessary to use dietary supplements to increase levels of the Serotonin neurotransmitter.
Many who are feeling depressed or stressed turn to Serotonin-boosting supplements to improve mood and promote feelings of well-being.
Serotonin cannot be supplemented directly as it is not orally bioavailable. If you were to take a Serotonin pill, this neurochemical would not be able to travel through your body and cross the blood-brain barrier, which is the filtration system that separates brain cells from circulating blood.
Instead, to increase Serotonin levels most people use either L-Tryptophan or 5-HTP supplements. L-Tryptophan is the amino acid from which Serotonin is derived. It is found naturally in dairy products, red meat, chicken, turkey, eggs, tofu, and other protein-rich foods.
When L-Tryptophan is consumed, most of this amino acid is directed to other functions in the body. A small portion of what you ingest can be used to make Serotonin. Tryptophan from food or supplements is broken down in the liver into the compound 5-Hydroxytryptophan (5-HTP).
The 5-HTP travels through the bloodstream to the brain, crosses the blood-brain barrier, and enters the brain. Once in the brain, the 5-HTP is converted into Serotonin.
For this reason, taking 5-HTP may be a more direct way to increase Serotonin levels than increasing Tryptophan food sources or taking Tryptophan supplements. This supplement has a high rate of oral bioavailability and in research studies has been shown to significantly raise Serotonin levels in the brain.
Using 5-HTP to Increase Synthesis of the Serotonin Neurotransmitter
Before using 5-HTP to raise levels of the Serotonin neurotransmitter, speak to your doctor to determine if this supplement is appropriate for you. 5-HTP is typically used at dosages between 50 – 200 mg, taken 1 – 3 times a day.
5-HTP is considered safe when used at low dosages to correct Serotonin deficiency. However, some side effects can occur including gastrointestinal upset, headache, vomiting, and diarrhea. High dosages increase the risk of side effects and should be avoided.
This supplement may interact with other drugs or supplements that affect the Serotonergic system. If you are taking drugs such as SSRIs (including Prozac, Paxil or Zoloft), consult with your doctor before using 5-HTP or other Serotonin-boosting supplements.
When taken at high dosages or combined with other Serotonin-boosting compounds, there is a risk of developing Serotonin Syndrome. Serotonin Syndrome occurs when there is an excess of Serotonin in the brain. Symptoms of this condition include excessive sweating, agitation, rapid change in blood pressure, irregular heartbeat, and fever. If left untreated, in severe cases, Serotonin Syndrome may be fatal.
Serotonin plays an important role in the regulation of mood, sleep and appetite. Low levels of this neurotransmitter have been linked to mood disorders including anxiety and depression. To learn more about how the Serotonin neurotransmitter may be affection your health condition, speak to your doctor.
Article last updated on: March 25th, 2018 by Nootriment