How to increase happiness in your body

How does serotonin work in the body and brain?

Serotonin is an important signalling molecule that fulfils many functions in the body, both as a hormone and as a neurotransmitter. In the brain, serotonin plays a central role in signal transmission between nerve cells, which is essential for processing and relaying information. A stable serotonin level contributes to emotional balance, promotes well‑being and supports creative thinking. An imbalance, on the other hand, can lead to mood and motivational disorders.

Besides its effect on the mind, serotonin also influences numerous physical processes. In the central nervous system it is involved in regulating the sleep‑wake cycle, pain perception and appetite. It also plays a key role in the reward system and supports memory functions. Outside the brain, serotonin affects intestinal movement, regulates the diameter of blood vessels, promotes blood clotting and influences body temperature.

Its diverse effects depend on the receptors it binds to. The so‑called 5‑HT receptors mediate different reactions such as relaxation, arousal or calming. In combination with other neurotransmitters like dopamine and noradrenaline, serotonin can help alleviate anxiety and depression symptoms and enhance drive and performance.

How is serotonin produced in the body?

Serotonin is produced mainly in the intestinal mucosa, but also in the brain, although it cannot cross the blood‑brain barrier. The starting point for serotonin production is the amino acid tryptophan, which the body cannot synthesise and must therefore obtain from food. Without sufficient tryptophan, the body cannot make serotonin.

The conversion of tryptophan into serotonin occurs in two steps: first tryptophan is converted to 5‑hydroxytryptophan (5‑HTP) with the help of vitamin D. Then 5‑HTP is converted into serotonin with the help of vitamin B6.

The produced serotonin is stored in small storage units, vesicles, within the cells. When the body needs it, it is released. Afterwards it is either reabsorbed into the vesicles or broken down by enzymes such as monoamine oxidase A (MAO‑A). The end product of the breakdown is 5‑hydroxyindoleacetic acid, which is excreted in the urine.

Low serotonin level: what causes it?

A low serotonin level in the brain can have various causes. Common triggers are psychological stresses such as chronic stress, anxiety, depression and sleep disorders. Stress has a particularly strong effect because it promotes the release of the stress hormone cortisol, which in turn lowers serotonin levels. This interaction between serotonin and cortisol can create a vicious circle in which serotonin levels continue to drop.

Another important factor for low serotonin is an inadequate supply of essential nutrients such as L‑tryptophan and vitamin B6, which are necessary for serotonin synthesis. These nutrients must be obtained through the diet because the body cannot produce them itself. An unbalanced diet can therefore lead to a serotonin deficiency.

A lack of vitamin D can also contribute to low serotonin levels, especially in winter months when the body's own production of vitamin D is reduced due to limited sunlight exposure.

How can a serotonin deficiency present?

A deficiency of serotonin can cause both psychological and physical complaints. On a physical level, a serotonin deficiency often manifests as headaches, muscle pain, sleep disturbances, fatigue and high blood pressure. Affected individuals may also experience irritable bowel symptoms, concentration problems and a strong craving for carbohydrate‑rich foods.

Psychologically, a low serotonin level shows up as increased irritability, mood swings, pronounced anxiety and lack of drive. People with serotonin deficiency often find less pleasure in activities they usually enjoy and may suffer from severe stress or panic attacks. Phobias or low self‑esteem are also possible.

Because serotonin plays a major role in mood regulation, a deficiency is associated with mental disorders such as depression and anxiety disorders. Studies have indeed shown that people with depression often have significantly lower serotonin levels. However, there is no conclusive evidence that a serotonin deficiency directly causes depression.

Serotonin: what do elevated levels mean?

An elevated serotonin level can have serious health consequences and is often referred to as serotonin syndrome. This syndrome most commonly occurs with tumours of the gastrointestinal tract, especially carcinoid tumours (hormone‑producing tumours). These tumours lead to excessive serotonin production. Typical symptoms are racing heart, facial flushing, abdominal cramps and diarrhoea.

Elevated serotonin levels can also be caused by other conditions such as epilepsy or coeliac disease (gluten intolerance), since increased serotonin values have been associated with these disorders as well.

Another reason for high serotonin levels is the intake of certain medications or drugs. Antidepressants, migraine treatments and strong painkillers can cause serotonin levels to rise dangerously, which can lead to a life‑threatening state. This increase often occurs shortly after intake and is characterised by symptoms such as restlessness, confusion, increased heart rate, raised blood pressure, dilated pupils, muscle twitching, sweating, chills, diarrhoea and headaches.

In severe cases, life‑threatening symptoms such as high fever, convulsions, irregular heartbeat or even loss of consciousness can occur. Immediate medical help is required when these signs appear, as the condition can lead to serious complications if left untreated.

How does serotonin affect your sleep?

Serotonin plays an important role in sleep regulation, as it controls the transition between different sleep phases. It enables falling asleep and helps the body move into deep and REM sleep, which are essential for restorative rest. Serotonin production also stabilises the sleep cycle and prevents nocturnal awakenings.

Serotonin is synthesised from the amino acid L‑tryptophan, which is taken in with food. An adequate supply of L‑tryptophan promotes serotonin production and thus sleep onset and maintenance. A healthy serotonin level is therefore important for physical and mental recovery during sleep.

Practical tips to increase your serotonin level

• Spend time outdoors in daylight every day to stimulate serotonin production. Even on cloudy days, daylight has a positive effect.
• Exercise regularly, whether through sports or extended walks. Physical activity has been shown to increase serotonin levels.
• Eat tryptophan‑rich foods such as bananas, salmon, eggs or cashews. Combine them with carbohydrates to promote uptake into the brain.
• Choose dark chocolate with a high cocoa content, as it contains tryptophan and magnesium, which can improve mood.
• Eat foods high in omega‑3 fatty acids, such as fatty fish or walnuts, as these promote serotonin release.
• Include vitamin D in your diet, for example through fatty fish like salmon or dietary supplements, especially during the winter months.
• Reduce stress by practising relaxation techniques such as yoga, meditation or breathing exercises, which positively influence serotonin levels.
• Eat fibre‑rich foods like lentils or whole grains to support a healthy gut flora, which is closely linked to serotonin production.
• Incorporate regular social interactions into your daily life, as positive interpersonal relationships boost well‑being and serotonin levels.

Serotonin is an important neurotransmitter that promotes emotional balance and influences numerous bodily functions. A healthy serotonin level stabilises mood, improves sleep and supports overall well‑being.