NPY and major depressive disorder: NPY has an influence on cellular communicationsinside the body, food uptake, connections with obesity, cardiovascularcontrol, circadian rhythm, stress, anxiety, and depression.43−45 Studies have shown that an abnormal concentration of NPY in thebody can lead to major diseases and disorders, particularly stress-relatedhealth problems.46,47 Therefore, the quantificationof NPY in body fluids can pass on the information about an individual’sstress level.