Not getting enough sleep definitely affects mood swings. It can be hard to get enough sleep sometimes when your friends want to talk or hang out at night, but remember that it's important to get enough sleep so that you can feel your best.  Of course you don't want to miss out on hanging out with your friends, but don't make it an every night thing. It's suggested that teens get 8 to 10 hours of sleep each night. Make sure you eat regularly and eat the right foods. This means staying away from loads of sugar and including a balance of carbohydrates, protein, fruits, and veggies every day. If you skip a meal or don't eat enough, notice if this affects your mood. Make sure you're eating regularly to avoid mood swings related to hunger.  A diet that is high in saturated fats and caloric levels may lead to depression.  Those who consume more water, fiber, ascorbic acid, tryptophan, magnesium and selenium have better moods overall. Diets that are heavy on legumes, fruits and vegetables, such as the Mediterranean diet, meet these criteria.  Add folic acid, which can be found in leafy greens and beans. Caffeine can interrupt your sleep. It can also cause nervousness, anxiety, shakiness, and dehydration. If you experience moodiness frequently, remove caffeine and see if it helps. It may be that one thing that pushes you over the edge.  The effects of caffeine are typically felt within five to 10 minutes and may last from one to five hours. Aftereffects may last for up to 24 hours.  A strong dose of caffeine may lead to jitteriness, increased heart rate, irritability, and restlessness. A strong dose is between 150-400 mg. (A coffee contains roughly 150 mg per 12 oz.; an energy drink is in excess of 100 mg per 12 oz; a diet coke is around 46mg per 12oz (or one can).)  If you do consume caffeine, try not to exceed 50-150 mg, or about one 12oz cup of coffee. Exercise can help you improve your mood, increase self-esteem, and improve sleep. When you exercise, your body releases endorphins, which help you get into a better mood and de-stress. Exercise is good for physical and emotional health.  It's recommended that teens get one hour of exercise almost every day.  Maybe you hate sports, but that doesn't mean you can't exercise. Walk the dog, jump on the trampoline, go in-line skating, or go dancing. Sometimes you may want to be left alone and avoid people altogether, and that's okay. But it's also important to spend time with friends. Maybe you have one friend you can tell everything to; talk to her and let her know how you're feeling. Talk to a trusted adult, such as a parent, guidance counselor, or coach. Talk to your best friend, or maybe say hello to your crush. Sometimes mood swings are just mood swings, while other times they can indicate a more serious disorder. If your mood swings are more intense than other girls', talk to a trusted adult about seeing a mental health professional to explore other causes. If you've noticed other symptoms, such as racing thoughts, incoherence, disjointed thoughts, or periods of excessive energy, this can indicate symptoms of other more serious disorders. Talk to an adult and a mental health professional.

Summary:
Get some sleep. Watch how hunger affects your mood. Avoid caffeine. Get some exercise. Talk to someone. Understand that mood swings can indicate more serious disorders.