This results in fatigue, muscle weakness, depressed mood and decreased appetite.

They're an excellent source of folic acid, a lack of which has been linked to depressed mood.

Research has linked insulin resistance with a depressed mood, too.

Studies indicate that task-unrelated thoughts are common in people with low or depressed mood.

Individuals who score high on neuroticism are more likely than the average to experience such feelings as anxiety, anger, envy, guilt, and depressed mood.