Advice needed. Followed only for a week?

Not a health problem actually, but just needed advice. I am a student and this happens to be my final semester bcz of which I am pushing myself harder everyday- which basically includes sleeping for only 3-4 hours a day and studying for the rest. I also tend to drink less water during the entire day and skip meals. The stress levels are at its peak. But just for a week I am planning to follow this extreme sort of timetable. I suffer from thyroid and vitiligo which I feel is mainly stress induced and not a genetic problem. Recently I lost 3 kgs just bcz of my habit to skip meals. I am skinny as it is. So my query is that how can I recover back to health? And will this tendency to sleep for 3-4 hours be harmful if followed only for a week?