Question For Vegans.....Any Suggestion?

Sounds like a problem other than her veganism. I am 65 and I have been a vegetarian for about 40 years. I have never had any urge for sweets and although I only sleep 5-6 hours a night I have no trouble getting that amount. I suggest you have her speak to a psychologist specializing in eating disorders.

It could be any number of things and she should probably consult her physician.  

I was a vegetarian for 10 years and decided to become a vegan.  I ate very well and even had my doctor do a full blood test to make sure I was getting all the right nutrition in my diet: I was.  I ended up going back to being a vegetarian, however, because I found I was unable to get enough fat in my diet and lost more weight than I would have liked.

It is possible that your daughter's sweet cravings have to do with not having adequate variety in her diet or simply a lack of adequate 'good' calories.  Thus she is binging on sweets to compensate and because they are full of sugar, it is causing weight gain.

I'm just speculating based on my own experience though... She really should see her doctor as soon as possible as it sounds like she is having a pretty rough time at the moment.

If she is really vegan she needs to read the ingredients in the sweets she eats. I am mostly living a vegan lifestyle and found that I cannot include any of the normal sweets from the grocery store in my diet. They either contain milk if you are having something with chocolate or gelatin ( cooked from bones and animal parts) if it is a chewy candy.
It was a frustrating journey for me but so worth it. My physical and mental health are improving by the day
:)