Sleeping a lot and an unpleasant attitude can certainly be signs of depression as well as many other things. Sometimes we sleep more than usual to avoid being awake, especially if we are faced with things during the day that seem to be out of our control.
Does your friend know you are concerned about these things? Will she discuss this with you openly? If so, see if she will share with you what may be bothering her. And, if she is unwilling to be completely open with you, try to help her find someone with whom she can be, such as another friend, relative, counselor, or whomever.
Let me know how things go.
Best of Health,