What Causes Cyanosis Of The Hands?

My 21 yr old daughter just called and said that she has had problems today with her hands turning blue, an now an ashen gray color. This is mid-term week at school and she has not slept much and drinks cofee occasionally. ALso, about 3 yrs ago she was diagonised with MVP. Can his be the cause? She said today she could feel some eird palpitations but attribute it to the caffiene.