Depression is not just a feeling of sadness. Depression is a persistent period of depressed mood, complete loss of interest, lack of energy, poor focus, poor appetite, insomnia or hypersomnia , excessive guilt/ruminations and at most times suicidal thoughts. These symptoms interfere with daily functioning.

Common anxiety disorders include social anxiety, panic disorder, generalized anxiety disorder, agoraphobia and specific phobia. Social anxiety is the fear of being in social places due to fear of being negatively judged.Generalized anxiety is persistent worry about daily challenges out of proportion to the perceived threat. Panic disorder is consistent panic attacks that come on suddenly and without warning. Specific phobia is anxiety caused by fear of a specific object such as spiders or needles.

Bipolar disorder is a period during which the individual has elevated/euphoric mood accompanied by decreased need for sleep, feeling much more confident than usual, having racing thoughts, and flight of ideas. In the same period the individual will have extreme rage/irritability/anger as well as periods of depressed mood.

In schizophrenia, there is hallucinations, delusions and grossly disorganized behavior or speech. The patient usually cannot reality test.

After a traumatic event, individuals who develop PTSD will have nightmares, flashbacks as if they are reliving the event, startled/over exaggerated response, avoidance of the stimuli, self-destructive behaviors, social isolation and hypervigilance.