M:I'm so tired I can't see straight.
    W:You're been tired a lot lately,haven't you?
    M:Well,for the last few weeks I've had to stay up most of the night to observe star configurations for a project for my astronomy class. It's awful,no matter what time I go to bed,I always wake up at six a.m.That's the time I usually get up.
    W:Your biological rhythms probably haven't adjusted to your new schedule. I've read that some people have a lot of trouble when their sleep rhythms are interrupted. Even sleeping don't help them.
    M:I know,in fact,I've heard that there're now several special treatment centers for sleep disorders across the country; some people sleep too little,some sleep too much,some walk in their sleep.
    W:I'd like to find out how they treat problems like that.Maybe you should go to one of those centers.
    M:Not me.After next week,my project will be finished and I'll go back to my regular hours. Now,I know for sure that I don't want to be an astronomer.