im not a sleep expert but is sounds like you would be putting your body through a lot. Not to sure if yourbody would be able to sleep 18 hrs at a time and im sure your body would get very tired. I would speak to a Dr to seek their professional advice

Good Luck

Natalie

I have done it. When i'm 16. In a week there's no problem at all. In a month i collapsed due to digestion disorder. If u want to change ur sleeping habbit, i suggest u do it slowly. Right now i manage to sleep at least 2-4 hours a day in 5 days, the rest two days i sleep at least 12 hours a day.