A mood swing is an extreme or rapid change in mood. Such mood swings can play a positive part in promoting problem solving and in producing flexible forward planning. However, when mood swings are so strong that they are disruptive, they may be the main part of a bipolar disorder.
Speed and extent 
Mood swings are universal, varying from the microscopic to the wild oscillations of manic depression, so that a continuum can be traced from normal struggles around self-esteem, through cyclothymia, up to a depressive disease. However most people's mood swings remain in the mild to moderate range of emotional ups and downs.
The duration of mood swings also varies. They may last a few hours - ultradian - or extend over days - ultrarapid: clinicians maintain that only when four continuous days of hypomania, or seven days of mania, occur, is a diagnosis of bipolar disorder justified.
In such cases, mood swings can extend over several days, even weeks: these episodes may consist of rapid alternation between feelings of depression and euphoria.
Many different things might trigger mood swings, from unhealthy diet or life style to drug abuse or hormonal imbalance.
A major cause of mood swings is hyperactivity sometimes accompanied by inattentiveness, symptoms associated with Attention deficit hyperactivity disorder. If the mood swing is not associated with a mood disorder, treatments are harder to assign. Most commonly, however, mood swings are the result of dealing with stressful and/or unexpected situations in daily life.
Brain chemistry 
If a person has an abnormal level of certain neurotransmitters (NTs) in their brain, it may result in having mood swings or a mood disorder. Serotonin is a neurotransmitter in the brain that is involved with sleep, moods, and emotional states. A slight imbalance of this NT could result in depression. Norepinephrine is a neurotransmitter that is involved with learning, memory, and physical arousal. Like serotonin, an imbalance of norepinephrine may also result in depression.
- Attention deficit hyperactivity disorder.
- Autism or other pervasive developmental disorder.
- Bipolar disorder or cyclothymia.
- Borderline personality disorder.
- Dementia, including Alzheimer's disease and Huntington's disease.
- Hypothyroidism or hyperthyroidism.
- Intermittent explosive disorder.
- Major depressive disorder.
- Premenstrual syndrome.
- Schizoaffective disorder.
- Seasonal affective disorder.
Exercise, treats, seeking out small (and easily attainable) triumphs, and using vicarious distractions like reading or TV, are among the techniques found to be regularly used by people in breaking depressive swings.
Learning to bring oneself down from grandiose states of mind, or up from exaggerated shame states, is part of taking a proactive approach to managing one's own moods and varying sense of self-esteem.
See also 
- Peter Salovey et al, Emotional Intelligence (2004) p. 1974
- Sigmund Freud, Civilization, Society and Religion (PFL 12) p. 164
- Otto Fenichel, The Psychoanalytic Theory of Neurosis (1946) p. 406
- Daniel Goleman, Emotional Intelligence (1995) p. 57
- S, Nassir Ghaemi, Mood Disorder (2007) p. 243-4
- Hockenbury, Don and Sandra (2011). Discovering Psychology Fifth Edition. New York, NY: Worth Publishers. p. 549. ISBN 978-1-4292-1650-0.
- "Bipolar Mood Swings, Stabilizers, Triggers, and Mania." WebMD. WebMD, 03 May 0000. Web. 29 Feb. 2012.
- Neurobiology of Mood Disorders.
- The Four Major Neurotransmitters.
- Paul Gilbert, Overcoming Depression (1999) p. 63
- Goleman, p. 73-4
- Terence Real, I Don't Want to Talk About It (1997) p. 279
Further reading 
- Ronald R. Fieve, Moodswing (1989)
- Susanne P. Schad-Somers, On mood swings (1990)