Types of Depressive Illnesses
There are a number of different depressive illnesses, all with various symptoms, degrees of severity, and duration; below are some of them.
SAD (Seasonal Affective Disorder) – this illness has to do with a person’s reaction to the amount of light a person receives. Symptoms of depression – low energy, fatigue, overeating may appear when the days begin to get shorter and there is less sunlight. People who have Seasonal Affective Disorder may produce an excess of the hormone melatonin, which is related to the body’s sleep cycle and biological clock.
Unipolar Depression – person has times when he/she feels normal, and other times when he/she feels depressed, slowed-down, or in a fog. Their ability to function normally may be significantly impaired. A person may have only one or two episodes, or may continue to have episodes throughout his or her lifetime.
Bipolar Illness or Manic Depression – there are two forms of this disease. With the first type, Bipolar I, a person may have dramatic mood swings, from severe lows to extreme highs (mania). A person who is experiencing mania may have excessive energy, he or she may feel restless and unable slow down, appearing hyper. This state causes grandiose thinking, impaired judgment, and often times embarrassing social behavior. With the second type, Bipolar II, the manias are milder (hypomania) and the lows may be of any severity. A person experiencing hypomania may be very talkative and social, their thinking may be extraordinarily clear and sharp, with heightened creativity. They feel in a wonderfully good mood, but eventually sink into a low period.

Dysthymia – this is chronic mild to moderate depression. A person usually continues to function, but just doesn’t experience the pleasure out of life like a healthy person does.
Cyclothymia – a form of bipolar illness, this is a mood rollercoaster. A person may feel up one day and down the next, or up one week and down the next. Seemingly unpredictable. Periods of normal mood may be few and far between. Hypomanias occur, along with mild depressions.
Atypical Depression – person can still have fun and experience pleasure if an opportunity presents itself, such as a party or good news, but the feeling is short-lived. Heaviness, fatigue, and lack of motivation then recurs until the next pleasurable occasion comes up. There may be moodiness, plus at least 2 of these 4 symptoms; oversleeping, overeating, extreme fatigue and rejection sensitivity.
Premenstrual Syndrome – seems to be related to depression in some people, with symptoms of irritability, nervousness, sadness, low energy, and physical symptoms of body aches and bloating presenting themselves prior to a woman’s menstrual period.