I have gone through the hardest two weeks in this semester,having the final examinations.Because of laziness,I had to sacrifice my sleeping time to prepare for the exams yesterday.At first I thought I was going to stay up all night in order to pass the test.So I drunk two bottles of coffee to keep awake.To my surprise,it seemed that I underestimated myself since it only took me about less than 3 hours to finish my preparation.However,unfortunately I couldn't help but stay awake after I drunk two bottles of strong coffee.Although I tried hard to calm myself down and fall asleep,I still lay in bed,awake,thinking about things happened in that day.Therefore,I got up and tried to focus on reading textbooks.which I became bored with soon.And then I played my cell phone for a while,telling one of my friends that I couldn't go to sleep because of the coffee,who was also going to stay up all night.In reply,she sent me "hahahaha" to show that what happened to me amused her.Afterwards,I tried to go to sleep for two times but I failed,and then I decided to focus on study but I failed again.And then I realized that coffee can keep you awake all night but it cannot make you concentrate on the thing that really matters.I forgot the specific time when I eventually fell asleep.But it's hard to forget the moment when the clock was ringing,I got up and I was exhausted in lack of enough sleep.In the end,I found that studying all night only can make you tired rather than help you pass the test.