There are more than 10 signs of depression, according to Mayo Clinic. Symptoms that involve emotions include feelings of persistent sadness, irritability, frustration, guilt or worthlessness. Mental abilities are impaired, such as difficulties concentrating, remembering and deciding, lack of interest in pleasant daily activities, and thoughts of death or suicide.
Physical signs include insomnia or too much sleep, food cravings or reduced appetite, lack of energy, agitation or restlessness, and slowed speech or movement, Mayo Clinic explains. Physical problems such as back pain or headaches develop, but no cause is apparent. People's tempers flare up over relatively minor matters. Sometimes individuals who are depressed attempt suicide.