Low serotonin syndrome

Nature 
Low levels of serotonin are associated with sleep problems, depression, anxiety, compulsive disorders (including eating disorders), restless leg syndrome, migraines, fibromyalgia and low pain threshold. Many people that are afflicted with one of those conditions often have others, which has led some researchers to label them collectively as "low serotonin syndrome.
Type 
(E) Emanations of other problems