Opportunity Cost.

Recently, a decision I've had to make is whether or not to read a book that is due for English or to go to bed at an earlier time. The book is due in less than a week, but there's also a flu/cold/virus going around school that requires my immune system to be working, which involves getting rest. 

In the end I decided to read my book because I knew that I needed to do well on it and I would have to spend time reading it later. I also figured that it would benefit me later in the week because I normally procrastinate on projects like these. Although I was able to get through a few chapters, in the morning I was exhausted and irritated. If I had gone to sleep I would have been more well rested and in a better mood. In addition, being more awake during the day would help me focus better in school.