Seasonal affective disorder (SAD) is a mood disorder that is characterized by symptoms that occur at the same time each year, usually during the darker, shorter days of fall and winter.Currently called major depressive disorder with seasonal pattern.SAD is believed to be triggered by a disturbance in the normal circadian rhythm of the body.Light entering through the eyes influences this rhythm, and any seasonal variation in night/day pattern can cause a disruption leading to depression.

Seasonal affective disorder (SAD)

Premenstrual dysphoric disorder (PMDD) produces similar symptoms, but those related to mood are more pronounced.PMDD symptoms may include:<ul><li>Extreme fatigue</li><li>Feeling sad, hopeless, or self-critical</li><li>Severe feelings of stress or anxiety</li><li>Mood swings, often with bouts of crying</li><li>Irritability</li><li>Inability to concentrate</li><li>Food cravings or binging</li></ul>

Premenstrual dysphoric disorder (PMDD)

Postpartum depression (PPD) is clinical depression that occurs following childbirth.Pregnancy can bring about significant hormonal shifts that can often affect a woman's moods.PPD symptoms are more severe and longer-lasting.Such symptoms can include:<ul><li>Low mood, feelings of sadness</li><li>Severe mood swings</li><li>Social withdrawal</li><li>Trouble bonding with your baby</li><li>Appetite changes</li><li>Feeling helpless and hopeless</li><li>Loss of interest in things you used to enjoy</li><li>Feeling inadequate or worthless</li><li>Anxiety and panic attacks</li><li>Thoughts of hurting yourself or your baby</li><li>Thoughts of suicide</li></ul>

Postpartum depression (PPD)

Atypical depression is a type of depression that does not follow what was thought to be the "typical" presentation of the disorder. In general, people with atypical depression experience similar symptoms as those with major depressive disorder (MDD) but with one crucial difference: mood reactivity. In other words, a person's mood is able to improve if something positive happens.Symptoms:<ul><li>Excessive eating or weight gain</li><li>Excessive sleep</li><li>Fatigue, weakness, and feeling "weighed down"</li><li>Intense sensitivity to rejection</li><li>Strongly reactive moods</li></ul>

Atypical depression

When people use the term clinical depression they are generally referring to major depressive disorder (MDD).﻿Major depressive disorder is a mood disorder characterized by a number of key features:<ul><li>Depressed mood</li><li>Lack of interest in activities normally enjoyed</li><li>Changes in weight</li><li>Changes in sleep</li><li>Fatigue</li><li>Feelings of worthlessness and guilt</li><li>Difficulty concentrating</li><li>Thoughts of death and suicide</li></ul>

Major depressive disorder (MMD)

People might experience brief periods of not feeling depressed, but this relief of symptoms lasts for two months or less. While the symptoms are not as severe as major depressive disorder, they are pervasive and long-lasting.PDD symptoms include:<ul><li>Feelings of sadness</li><li>Loss of interest and pleasure</li><li>Anger and irritability</li><li>Feelings of guilt</li><li>Low self-esteem</li><li>Difficulty falling or staying asleep</li><li>Sleeping too much</li><li>Feelings of hopelessness</li><li>Fatigue and lack of energy</li><li>Changes in appetite</li><li>Trouble concentrating</li></ul>

Persistent depressive disorder (PDD)

So all together you have:<ol><li>Major depressive disorder (MMD)</li><li>Seasonal affective disorder (SAD)</li><li>Atypical depression</li><li>Persistent depressive disorder (PDD)</li><li>Bipolar disorder (BPD)</li><li>Postpartum depression (PPD)</li><li>Premenstrual dysphoric disorder (PMDD)</li></ol>

All depressions

Bipolar disorder is a mood disorder characterized by periods of abnormally elevated mood known as mania. These periods can be mild (hypomania) or they can be extreme. The vast majority of those with bipolar disorder also have episodes of major depression.In addition to depressed mood and markedly diminished interest in activities, people with depression often have a range of physical and emotional symptoms which may include:<ul><li>Fatigue, insomnia, and lethargy</li><li>Unexplained aches, pains, and psychomotor agitation</li><li>Hopelessness and loss of self-esteem</li><li>Irritability and anxiety</li><li>Indecision and disorganization</li></ul>

Bipolar disorder

From a medical standpoint, depression is defined​ as a mood disorder that causes a persistent feeling of depressed mood or sadness and the often profound loss of interest in things that usually bring you pleasure.Depression affects how you feel, think, and behave and can interfere with your ability to function and carry on with daily life. There are many different causes of depression, some of which we don't fully understand. Seven of the more common types of depression include the following.

What is depression?

Depression symptoms vary and stem from different reasons, depending on the type. Here are the seven basic types of depression.