Can you try not to think about all mood swings like a medical problem, but as a part of your character and your age?
You are miles away from your mother, stressing over your studies and everyday life.
Try to find a strength to accept some part of your attitude and a strength to beat some.
It's normal for you age not to feel sleepy till late night hours and finding difficult to wake up early in the morning.
Don't give yourself unreal (it's not the right word

) tasks like putting your alarm to wake you up early in the morning if you already know that you want to sleep for longer, because this will bring you a disappointment. Try to give yourself reasons to do something because of other people, too, not only for yourself. This worked with me. I can easily do some good and pleasant things for other people (member of family, friends), but I'll skip doing it for myself. There were days when I just didn't want to go for exams, but I was doing it just because I knew how was that important for my mum.
It's normal to have days of low. Accept this as a way for your body to refilled with the energy for coming days.
You may try to do some changes in your lifestyle. Eat healthy and light food (food that gives you energy, not food that takes it from you to be dissolved), stop smoking or drinking too much coffee if you have them as a habit.
Don't feel disappointed.
It takes years and life experience (having kids and taking care of them, you wont have time to think how you feel today) to learn how to live with mood swings.
Best wishes!
Marija