There is well researched merit to this.

I have a book called "Potatoes Not Prozac" written by Phd Kathleen DeMaisions.

Serotonin is made from the amino acid Tryptophan. Tryptophan need carbs, timed without protein, to cross the blood brain barrier to make serotonin.

A small amount of complex carb, eating with fat but not protein will facilitate this happening.

Kathleen does not advocate eating sweets or simple carbs. She feels these cause an imbalance in our beta endorphin system by causing beta endorphin uploading, then withdrawl, causing a vicous circle of sugar addiction.

The book is an excellent read.

Otherwise do a search on the net about diet and serotonin.

I'm not saying you need to go high carb, just be aware that high protein low carb diets can cause depression in 'some' people, and the remedy is to eat a complex carb, like a slice of sprouted bread, apple, etc, without protein, late in the day, or before bed. Don't eat protein for 2 hours before or 3 hours afterward.

The research is compelling. If you do have a tendency toward depression, do a little reading...

Maggie