By Sydney Rumley, M.S., LLP

“OMG, I’m so bipolar today!”

“My mood changes so much, I must have bipolar.”

“Ugh, I’m just so crazy—my mood never seems stable.”

Sound familiar? These are all quotes that you may have heard (or even said) before. I know I’ve heard them, because referring to “bipolar” as mood fluctuations has become the norm when you don’t work in the field of mental health. But in reality, what looks like bipolar disorder may actually be borderline personality disorder (BPD) or even just normal mood swings. Misusing these terms not only spreads confusion but also adds to the stigma surrounding mental health. Let’s break down the differences.

What Is Bipolar Disorder?

Bipolar disorder is a mood disorder characterized by episodes of mania/hypomania and depression (American Psychiatric Association, 2022).

Manic episode: Persistently elevated, high-energy, racing thoughts, irritability, impulsive or risky behavior, goal-directed mood for at least 1 week.

Hypomanic episode: Similar symptoms lasting at least 4 consecutive days.

Depressive episode: Low mood and loss of interest/pleasure, fatigue, changes in sleep or appetite, trouble concentrating lasting at least 2 weeks.

These episodes occur over defined time periods. They are not rapid mood swings from hour to hour—a common misconception.

What Is Borderline Personality Disorder (BPD)?

In borderline personality disorder (BPD), one of the diagnostic criteria is significant mood instability and

reactivity that usually lasts “a few hours and only rarely more than a few days” (American Psychiatric Association, 2022). Some portrayals of “bipolar disorder” in the media are often more reflective of BPD.

Mood changes in BPD often last a few hours to a couple of days, rarely longer.

Individuals may struggle with intense emotions, difficulty regulating mood, and sensitivity to rejection or abandonment.

Emotional shifts can feel extreme and happen quickly, which is why BPD is sometimes mistaken for bipolar disorder.

Could It Just Be Mood Swings?

“But my mood still fluctuates! Does that mean I have bipolar disorder or BPD?”. Potentially, because diagnosing someone

with a mood disorder requires a lot of inquiry. However, the more likely answer is that mood changes are not always

associated with a psychiatric condition. There are so many factors that can cause our mood to shift: how well you slept,

hormonal changes, elevated stress, significant life events, the list goes on and on. While we may not always enjoy

experiencing certain emotions (especially those that are more uncomfortable, such as sadness, anger, stress, etc.), that

doesn’t necessarily mean that the emotional instability is indicative of a larger problem. However, if you find yourself

struggling with emotion regulation or want to understand your emotional experiences better, therapy can be a fantastic tool to add to your repertoire.

When to Seek Support

If you notice your mood swings are:

Disrupting relationships, work, or school,

Lasting longer than expected,

Or paired with difficulty managing emotions…

…then it may be time to seek support. A qualified therapist can help you explore your emotions, clarify whether they’re part of a mental health condition, and provide effective coping strategies.

The Bottom Line

Bipolar disorder = distinct episodes of mania/hypomania and depression lasting days to weeks.

Borderline personality disorder = shorter, more reactive mood swings with intense emotional responses.

Mood swings = a normal part of life, often tied to sleep, stress, or daily events.

Understanding the difference reduces stigma, promotes compassion, and helps people get the right care.

References American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). https://doi.org/10.1176/appi.books.9780890425787