After several weeks of feeling apathetic and dissatisfied with his life, Mark has suddenly become extremely cheerful and so talkative he can't be interrupted. He seems to need less sleep and becomes irritated when his friends tell him to slow down. Mark's behavior is indicative of:

Bipolar disorder

Explanation:

Bipolar Disease, traditionally called Manic-Depressive Disease, is a psychiatric disease characterized by marked variations in mood, with repeated bouts of depression and happiness. The changes in mood, in one sense or another, have an important impact on the person's sensations, emotions, ideas and behavior, with an important loss of health and personality autonomy.

Explanation:

After several weeks of feeling apathetic and dissatisfied with his life, Mark has suddenly become extremely cheerful and so talkative he can't be interrupted. He seems to need less sleep and becomes irritated when his friends tell him to slow down. Mark's behavior is indicative of: bipolar disorder.

Bipolar disorder equally known as bipolar disease or manic depression. It is a mental illness characterized by severe moody shifts. These shifts can swing to an emotional high known as (mania or hypomania ) or emotional low known as depression.

When they become emotionally low depression sets in causing sadness, hopelessness, they seem to lose interest in almost every thing. When they become emotionally they feel bubbly,full of energy or unusually irritating to others. These mood swings have the ability to affect sleep, energy, judgment, behavior and the ability to think clearly.

Bipolar disorder is a mental illness marked by extreme shifts in mood. Symptoms can include an extremely elevated mood called mania. They can also include episodes of depression. Bipolar disorder is also known as bipolar disease or manic depression.

People with bipolar disorder may have trouble managing everyday life tasks at school or work, or maintaining relationships. There’s no cure, but there are many treatment options available that can help to manage the symptoms. Learn the signs of bipolar disorder to watch for.

b) the planets year length would be longer

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