It is critical that your body has what it takes to make the three key "happiness" neurotransmitters that your body needs. These are called serotonin, dopamine, and norepinephrine.
Serotonin is a neurotransmitter released in the brain. It's made from the amino acid tryptophan, which is a component of protein. High levels of tryptophan in the blood signal the brain to make serotonin, which has many beneficial consequences on mood, including the promotion of happiness, relaxation and the ability to get a good night's sleep.
Serotonin secretes chemicals onto neurons in the brain which helps promote feelings of contentment and well-being. The brain makes serotonin when it's signaled to do so. One signal is carbohydrate consumption, which explains why may people feel a sense of happiness upon eating a sugary or starchy snack.