depressed mood or sadness most of the time (for what may seem like no reason)
lack of energy and feeling tired all the time
inability to enjoy things that used to bring pleasure
withdrawal from friends and family
irritability, anger, or anxiety
inability to concentrate
significant weight loss or gain
significant change in sleep patterns (inability to fall asleep, stay asleep, or get up in the morning)
feelings of guilt or worthlessness
aches and pains (with no known medical cause)
pessimism and indifference (not caring about anything in the present or future)
thoughts of death or suicide