So while euphoria and impulsivity in someone with BPD might resemble a manic episode, the experience would be too brief to qualify as a manic episode.Second, the moods of bipolar disorder do not respond to changes in the environment, while the moods of BPD do respond to changes in the environment. That is, a positive event would not lift the depressed mood caused by bipolar disorder, but a positive event would potentially lift the depressed mood of someone with BPD. Similarly, an undesirable event would not dampen the euphoria caused by bipolar disorder, but an undesirable event would dampen the euphoria of someone with borderline personality disorder.Third, when people with BPD experience euphoria, it is usually without the racing thoughts and decreased need for sleep that are typical of hypomania, though a later 2013 study of data collected in 2004 found that borderline personality disorder diagnosis and symptoms were associated with chronic sleep disturbances, including difficulty initiating sleep, difficulty maintaining sleep, and waking earlier than desired, as well as with the consequences of poor sleep, and noted that "[f]ew studies have examined the experience of chronic sleep disturbances in those with borderline personality disorder".Because the two conditions have a number of similar symptoms, BPD was once considered to be a mild form of bipolar disorder or to exist on the bipolar spectrum. However, this would require that the underlying mechanism causing these symptoms be the same for both conditions.
The minds habit of suppressing and avoiding intensely painful emotions may provide some temporary feelings of relief, but dissociation can also lead to unhealthy coping mechanisms, while simultaneously causing the side-effect of blocking out or blunting positive emotions, thereby reducing the access of people with BPD to the valuable information those emotions provide: information that helps to guide effective, healthy decision-making in daily life. Psychotic symptoms
Though BPD is primarily seen as a disorder of emotional regulation, psychotic symptoms are fairly common, with an estimated 21–54% prevalence in clinical BPD populations. These symptoms are sometimes referred to as "pseudo-psychotic" or "psychotic-like", terms that suggest a distinction from those seen in primary psychotic disorders. Recent research, however, has indicated that there is more similarity between pseudo-psychotic symptoms in BPD and "true" psychosis than originally thought. Some researchers critique the concept of pseudo-psychosis for, on top of weak construct validity, the implication that it is "not true" or "less severe", which could trivialize distress and serve as a barrier to diagnosis and treatment. Some researchers have suggested classifying these BPD symptoms as "true" psychosis, or even eliminating the distinction between pseudo-psychosis and true psychosis altogether.The DSM-5 recognizes transient paranoia that worsens in response to stress as a symptom of BPD. Studies have documented both hallucinations and delusions in BPD patients who lack another diagnosis that would better account for those symptoms. Phenomenologically, research suggests that auditory verbal hallucinations found in patients with BPD cannot be reliably distinguished from those seen in schizophrenia.