9 ½ hours
The average amount of sleep that teenagers get is between 7 and 7 ¼ hours. However, they need between 9 and 9 ½ hours studies show.
c. racing heartbeat
The alarm stage of stress is more popularly known as the fight or flight stage stage. It is in this stage that the brain sends signals to the different parts of your body taking the message that you are in a perilous situation. Upon receiving the messages and your body started to react, you can choose between the flight and fight response. You can either fight or flee away from that dangerous place. This alarm stage of stress as explained by the father of stress, Hans Selye is commonly characterized by fast and racing heartbeats.
Well if you already have the silver stuff on your tooth the only way to get it out is if your tooth falls out or if the stuff scrapes off...or you could just lower the amount of sugar intake you have.
Hope I could help!!