Symptoms and Differences between Bipolar Disorder I and II

Bipolar disorder is a mental health condition defined by periods (better known as episodes) of extreme mood disturbances. Bipolar affects a person’s mood, thoughts, and behavior. 

There are two distinct types of bipolar: bipolar I and bipolar II. According to the Diagnostic and Statistical Manual of Mental Disorders, bipolar I disorder involves episodes mania and depression.

Bipolar II disorder involves a less severe form of mania called hypomania.

Causes of Bipolar Disorder

While the exact cause of bipolar I disorder remains unclear, genetics is believed to play a major role. This is evidenced, in part, by studies of twins in which one or both had a bipolar I diagnosis. In 40 percent of maternal twins (those with identical gene sets), both twins were found to be bipolar compared to only five percent of fraternal twins (who had individual gene sets).

Other contributing factors include abnormalities in a person’s brain circuitry, irregularities in dopamine production, and environmental factors such as childhood trauma or abuse.

Similarities Between Bipolar I and Bipolar II Disorder

Despite the major difference when it comes to mania in the two types of bipolar disorder, there are quite a few similarities.

Bipolar II disorder involves one or more major depressive episodes.

In bipolar I disorder, a major depressive episode (one or more) usually occurs, but it is not required. 

Common symptoms that occur in a major depressive episode include:

  • Insomnia or hypersomnia
  • Unexplained or uncontrollable crying
  • Severe fatigue
  • Loss of interest in things the patient enjoys during euthymia
  • Recurring thoughts of death or suicide
Both disorders include periods of euthymia—symptom-free or “normal” states.

Mania and Hypomania 

Manic episodes last at least seven days. An individual experiencing a manic episode may experience:

  • Feelings of euphoria
  • Less need for sleep
  • Increased sexual desire
  • Hallucinations or delusions
  • Marked increase in energy

During a manic episode, individuals may engage in risky or reckless behavior. For example, someone may indulge in risky sexual behavior, spend excessive amounts of money, or make impulsive decisions. 

An individual experiencing a hypomanic episode may experience similar symptoms but their functioning won’t be markedly impaired. Many individuals who experience hypomania associated with bipolar II, enjoy the increased energy and decreased need for sleep. 

An episode of hypomania does not escalate to a point that a person needs hospitalization, which may happen with a person experiencing mania—especially if he or she is becoming a danger to others and/or themselves. 

It’s important to note that experiencing mania does not automatically mean a person will become violent or dangerous. Sometimes people assume a “manic episode” means someone turns into a “maniac.” That’s no


Caveats When Diagnosing the Type of Bipolar Disorder

There are two important caveats that may further complicate the process of distinguishing the two types of bipolar disorder.

One is that although present psychotic symptoms are one of the things that differentiate bipolar I mania from bipolar II hypomania, someone with bipolar II may experience hallucinations or delusions during depressive episodes without the diagnosis changing to bipolar I.

The second is that someone with bipolar I disorder may also have hypomanic episodes. In fact, they commonly do. But, someone with bipolar II does not ever have a manic episode.

If a manic episode occurs in someone with bipolar II, the diagnosis will be changed.

Both Types of Bipolar Disorder Are Serious

Since hypomania is less severe than the mania that occurs in bipolar I disorder, bipolar II is often described as “milder” than bipolar I—but this is not completely accurate. Certainly, people with bipolar I can have more serious symptoms during mania, but hypomania is still a serious condition that can have life-changing consequences.

In addition, research suggests that bipolar II disorder is dominated by longer and more severe episodes of depression. In fact, over time, people with bipolar II become less likely to return to fully normal functioning between episodes.

One study specifically concluded that bipolar type II was linked to a poorer health-related quality of life compared to type I. This remained true even during long periods of euthymia.

Thus, experts tend to believe that bipolar II disorder is equally (if not more) disabling as bipolar I disorder because they are ill more often, have more lifetime days spent depressed, and don’t do as well overall between episodes.


When diagnosing bipolar disorder (regardless of the type), a physician or clinician must rule out other illnesses such as schizoaffective disorder, schizophrenia, delusional disorder, or schizophreniform disorder.

Bipolar disorder cannot be diagnosed like physiological illnesses where a blood test, X-ray, or physical exam can provide a definitive diagnosis. The diagnosis is based on a set of criteria that a person must meet in order to be considered bipolar.

An informed diagnosis would include specific tests to exclude all other causes. This may involve a drug screen, imaging tests (CT scan, ultrasound), electroencephalogram (EEG), and a full battery of diagnostic blood tests.

Challenges of Bipolar I Diagnosis

While specific, the review of bipolar criteria is also highly subjective. As such, cases are often missed. One study, presented at the Royal College of Psychiatry’s Annual Meeting in 2009, reported that more than 25 percent of people with bipolar disorder were incorrectly diagnosed and treated when seeking help from a mental health professional.

On the other hand, over-diagnosis of bipolar disorder is also a concern, particularly if exclusionary tests have not been performed.

A 2013 review of clinical studies demonstrated that bipolar disorder was incorrectly diagnosed in:

  • 42.9 percent of substance abuse treatment centers
  • 40 percent of patients with borderline personality disorder
  • 37 percent of cases where a clinician inexperienced in bipolar disorder made the call

Without an exclusionary diagnosis, the likelihood of misdiagnosis and abuse is strong. A study released in 2010 showed that, of 528 people receiving Social Security disability for a bipolar disorder, only 47.6 percent met the diagnostic criteria.


Treatment of bipolar I disorder is highly individualized and based on the types and severity of symptoms a person may be experiencing.

Mood stabilizers are most often part of the treatment process and may include:

  • A mood stabilizer, such as lithium
  • Anticonvulsives to stabilize mood swings
  • Antipsychotics to control psychotic symptoms such as delusions, hallucinations, and severe manic features
  • Antidepressants (less commonly prescribed as they can trigger a manic episode)

In more severe cases, electroconvulsive therapy (ECT) may be used to create minor seizures which can help relieve mania or severe depression.

Author: Marcia Purse


Upcoming Retreats

  • Aug  14 — Aug 22
  • Sep  17 — Sep 25
  • Nov  5 — Nov 15
  • Dec  13 — Dec 21
  • Jan  10 — Jan 20

Journey with us

Browse our gallery

Subscribe to our Newsletter

Articles, videos, books, quotes, retreat updates, and more...