Medical and public understanding of bipolar disorder has come a long way since the days when the mental illness was called “manic depression.” It is much better defined and more easily treated than it used to be, and while mental illnesses still have a certain stigma attached to them, more and more people are opening up about having bipolar disorder, hoping to break down negative perceptions.

For those who suffer from the condition, diagnosis is a crucial first step. The National Institute of Mental Health notes the hurdles these people face, saying doctors may not properly identify bipolar disorder if the person appears to have psychotic symptoms like hallucinations or delusions as a result of a severe mood swing, the hallmark of the illness. That could include thinking they have special powers during a manic episode, or believing they have committed a crime during a depressive one. Doctors may see those manifestations and misdiagnose schizophrenia. Further complicating matters, people with bipolar disorder also often have substance abuse issues, eating disorders, anxiety disorders and various physical health conditions like obesity and heart disease. In children, it can be hard to tell whether their moods are the result of a mental illness, are normal patterns, or stem from stress or trauma.

“Some people have bipolar disorder for years before the illness is diagnosed,” the NIMH says.

Usually it appears in the late teens or early adulthood, when the person starts to go back and forth between manic periods of extreme energy and positivity and depressive periods of intense sadness and low energy. The manic episode could also show itself with the person talking quickly about many different things, being irritable or agitated, and taking risks like having reckless sex or spending a lot of money. During depressive episodes, people can be forgetful and have trouble concentrating or show changes in eating habits. There are also “mixed episodes,” when someone shows both manic and depressive symptoms.

“Bipolar disorder is not the same as the normal ups and downs everyone goes through,” the NIMH explains. “The mood swings are more extreme than that and are accompanied by changes in sleep, energy level, and the ability to think clearly. Bipolar symptoms are so strong that they can damage relationships and make it hard to go to school or keep a job.” They also present a danger because sometimes people with bipolar disorder attempt suicide.

According to the Mayo Clinic, the manic episodes last days to weeks and the depressive episodes last at least a couple of weeks.

Doctors don’t know what causes bipolar disorder, but factors could include genetics and brain structure. Moods can also cycle with the seasons, the Mayo Clinic says, and some women experience bipolar symptoms during or right after pregnancy.

Bipolar disorder is not uncommon, and it is possible to control it and lead a normal life. There are even some famous actors with the mental illness, according to CBS News, including Carrie Fisher, who played Leia in Star Wars; Terminator star Linda Hamilton; comedian Russell Brand; action star Jean-Claude Van Damme; British Prime Minister Winston Churchill, who led the United Kingdom during World War II, also had the condition. Churchill “often referred to his bouts of intense, prolonged depression as his ‘black dog,’” CBS says. “When not battling depression he had incredible energy and was highly productive.”