Serotonin is the main hormone for happiness . It improves mood, prevents depression, is considered a neurotransmitter, and improves emotion and cognition, and low levels of serotonin lead to feelings of depression, suicidal tendencies, anger, sleep difficulties, migraines, and increased carbohydrate consumption. The body can produce serotonin from the amino acid tryptophan. 
Methods for increasing serotonin
There are several ways to increase serotonin levels in the body, such as: 
- Exposing to the sun, and spending some time in it for at least 20-30 minutes every morning or in the afternoon outside the home.
- Meditation and recovering happy memories, which helps the brain produce serotonin; The brain produces this hormone when feeling happy.
- Paying attention to the body getting enough vitamin "B", vitamin "B6", vitamin "B12" and vitamin "C"; Evidence has shown the ability of vitamin supplements to treat depression and increase human happiness.
- Exercise, such as running, walking, dancing, etc. These exercises help produce serotonin.
- Limit your sugar intake; Eating sugary foods reduces serotonin in the body and leads to bad mood, and reducing sugary foods helps protect the body from heart disease and diabetes.
- Eat foods rich in magnesium, such as dark leafy vegetables, fish, beans and bananas, which help treat bouts of depression and achieve happiness.
Adrenaline is called the energy molecule, which enhances the feeling of joy and happiness, creates more energy, and adrenaline causes an increase in heart rates, blood pressure, and increased blood flow to the muscles, and the "Epi-Pen" is part of the adrenaline used to treat severe allergic problems . 
The GABA hormone (GAPA) is an inhibitory substance that reduces the firing of nerve cells, and increases feelings of calm and comfort, and this hormone can be increased naturally through the practice of meditation and yoga exercises. A study from the Journal of Complementary Alternative Medicine found that practicing a 60-minute yoga session increases GABA levels by 27%, and some sedatives such as Valium and Valium and Xanax increase the production of GABA, but they contain many risks and side effects. Despite this, its use extends to a wide range. 
- Anne Marie Helmenstine, Ph.D. (25-9-2017), “What You Need to Know About Neurotransmitters” , www.thoughtco.com , Retrieved 10-1-2018. Edited.
- Katherine Hurst, "11 Ways To Increase the Serotonin In Your Brain (Naturally)" , www.lifehack.org , Retrieved 7-2-2018. Edited.
- Christopher Bergland (11-29-2012), “The Neurochemicals of Happiness” , www.psychologytoday.com , Retrieved 10-1-2018. Edited.