There are many causes of up-and-down moods, which can be referred to as mood instability. The commonest cause is the ups and downs of life, as circumstances change, people come and go from our lives, we have a problem at work or get a promotion. Parenting young children can lead to new stresses, sleep deprivation, etc.
However, mood instability may also be due to a psychiatric disorder, or a personality disorder. To help you learn the cause of your problem you would do best to consult a psychiatrist who is skilled in diagnosing and treating mood problems, as there are mood stabilizing medications available if the cause is not simply the ups and downs of
life. A good psychiatrist will spend an hour taking a careful history of your life, relationships, family history, and the duration and severity of your up moods and depressions. From this information he can make a helpful diagnosis and plan treatment to relieve your problem.