I think she was put on Concerta to help with her ADHD, and it has helped with her concentration in school, from what I know.

For the first question, most of her worst tantrums take place at night; so I don't know if she falls asleep because of the tantrum or because she's already tired. When she does throw a tantrum during the day, she usually leaves the house or hides in her room afterwards, which is followed by a call/trip to her friends for venting, but she doesn't fall asleep.

For the second question, when she's caught in a lie, she normally blames a friend or tries to convince us we don't remember the event correctly. For example, she stole a grey shirt of mine, lost it, and when asked where it went, she denied taking it. She went into the bedroom and grabbed another grey shirt, saying that was the one she took to school. Even when she had her tantrum later that day (after my mother punished her for stealing), she continued to deny what happened and spent the whole evening yelling at us for accusing her of something she says she didn't do. When my mother found my shirt in the back seat of the car the next day, her explanation was that my mother must have brought the shirt to the car with her. That's how things generally go when she gets caught doing something wrong. She's never claimed not to remember something, just made up stories about what happened.

My mother's concerned about adjusting my niece's medications too much due to her weight. The psychiatrist wanted to increase one of her medications (I've forgotten which one) and my mother was hesitant about it.