Signs and symptoms of mania include discrete periods of:

• Increased energy, activity, restlessness, racing thoughts, and rapid talking
• Excessive "high" or euphoric feelings
• Extreme irritability and distractibility
• Decreased need for sleep
• Unrealistic beliefs in one's abilities and powers
• Uncharacteristically poor judgment
• A sustained period of behavior that is different from usual
• Increased sexual drive
• Abuse of drugs, particularly cocaine, alcohol, and sleeping medications
• Provocative, intrusive, or aggressive behavior
• Denial that anything is wrong

Signs and symptoms of depression include discrete periods of:

• Persistent sad, anxious, or empty mood
• Feelings of hopelessness or pessimism
• Feelings of guilt, worthlessness, or helplessness
• Loss of interest or pleasure in ordinary activities, including sex
• Decreased energy, a feeling of fatigue or of being "slowed down"
• Difficulty concentrating, remembering, making decisions
• Restlessness or irritability
• Sleep disturbances
• Loss of appetite and weight, or weight gain
• Chronic pain or other persistent bodily symptoms that are not caused by physical disease
• Thoughts of death or suicide; suicide attempts

It may be helpful to think of the various mood states in manic-depressive illness as a spectrum or continuous range. At one end is severe depression, which shades into moderate depression; then come mild and brief mood disturbances that many people call "the blues," then normal mood, then hypomania (a mild form of mania), and then mania.

Some people with untreated bipolar disorder have repeated depressions and only an occasional episode of hypomania (bipolar II). In the other extreme, mania may be the main problem and depression may occur only infrequently. In fact, symptoms of mania and depression may be mixed together in a single "mixed" bipolar state.