How do I tell ordinary sadness apart from depression that needs treatment?

Ordinary sadness comes and goes with its causes, while depression is prolonged, deep and affects daily functioning even when circumstances improve. Notice how long it lasts: being sad for a few days after a loss is normal, but low mood that continues for weeks is no longer just an ordinary test. Also notice the effect on sleep, appetite, concentration and interest. If someone loses the ability to get through the day or withdraws completely, that is a sign they need help. Do not wait for it to become severe; seeing a doctor early leads to better recovery. Caring for the soul is as important as caring for the body. See mental health.