I think a case could be made for Josh being bipolar based on the information below.
Signs and symptoms of mania
In the manic phase of bipolar disorder, feelings of heightened energy, creativity, and euphoria are common. People experiencing a manic episode often talk a mile a minute, sleep very little, and are hyperactive. They may also feel like theyre all-powerful, invincible, or destined for greatness.
But while mania feels good at first, it has a tendency to spiral out of control. People often behave recklessly during a manic episode: gambling away savings, engaging in inappropriate sexual activity, or making foolish business investments, for example. They may also become angry, irritable, and aggressivepicking fights, lashing out when others dont go along with their plans, and blaming anyone who criticizes their behavior. Some people even become delusional or start hearing voices.
Hypomania symptoms
Hypomania is a less severe form of mania. People in a hypomanic state feel euphoric, energetic, and productive, but they are able to carry on with their day-to-day lives and they never lose touch with reality. To others, it may seem as if people with hypomania are merely in an unusually good mood. However, hypomania can result in bad decisions that harm relationships, careers, and reputations. In addition, hypomania often escalates to full-blown mania or is followed by a major depressive episode.
Common signs and symptoms of mania include:
Feeling unusually high and optimistic OR extremely irritable
Unrealistic, grandiose beliefs about ones abilities or powers
Sleeping very little, but feeling extremely energetic
Talking so rapidly that others cant keep up
Racing thoughts; jumping quickly from one idea to the next
Highly distractible, unable to concentrate
Impaired judgment and impulsiveness
Acting recklessly without thinking about the consequences
Delusions and hallucinations (in severe cases)
Signs and symptoms of bipolar depression
In the past, bipolar depression was lumped in with regular depression. But a growing body of research suggests that there are significant differences between the two, especially when it comes to recommended treatments. Most people with bipolar depression are not helped by antidepressants. In fact, there is a risk that antidepressants can make bipolar disorder worsetriggering mania or hypomania, causing rapid cycling between mood states, or interfering with other mood stabilizing drugs.
Despite many similarities, certain symptoms are more common in bipolar depression than in regular depression. For example, bipolar depression is more likely to involve irritability, guilt, unpredictable mood swings, and feelings of restlessness. People with bipolar depression also tend to move and speak slowly, sleep a lot, and gain weight. In addition, they are more likely to develop psychotic depressiona condition in which theyve lost contact with realityand to experience major disability in work and social functioning.
http://www.helpguide.org/mental/bipolar_disorder_symptoms_treatment.htm