It's a normal thing depending on how long it lasts. Diet can have a big impact on depression. Try exercise, works well for me but everyone is different. It could be a number of other things. If it consistently lasts longer than 2 weeks I think that classifies as clinical depression and I'd go see a professional. Just be weary of antidepressants. [spoiler]Feel free to pm. Sometimes just talking about it can help.[/spoiler]