Serotonin is a neurotransmitter; functions include regulation of appetite, mood and sleep. Low levels of serotonin can lead to carbohydrate cravings, depression, fatigue, irritability, social withdrawal & sleep disturbances.
How to influence Serotonin levels via Diet:
Tryptophan is the precursor to serotonin. Food Sources: almonds, avocado, bananas, beets, brown rice, cashews, chickpeas, miso, peanuts, pecans, pine nuts, tempeh, turkey, whole grain bread
Calcium activates multiple neurotransmitters in the brain including Serotonin. Food Souces: artichokes, cabbage, green leafy vegetables, kiwi, lima beans, pumpkin seeds, strawberies, watercress, yogurt
Essential Fatty Acids play a role in the formation of hormones, along with proper functioning of neurons & chemical reactions in the brain. Omega 3's found in chia, flax seed oil, mackerel, salmon, sardine, tuna, walnut oil. Omega 6' s found in canola oil, flax, grape seed oil, safflower oil, sunflower oil and wheat germ oil. Gamma-Lionleic Acid found in borage oil & primrose oil
The B vitamins (primarily Vitamin B6) are also required to produce Serotonin. Food Sources of B6: bran, cod, garlic, hazelnuts, pistacchios, salmon, spinach, tahini, wheat
It should be noted that severe deficiencies in Serotonin likely need medical attention, but including these foods in your diet can only bring benefit.