I have delayed sleep phase disorder (DSPD). That means I am unable to fall asleep until very late at night and normally sleep very late in the morning. My sleep doctor sent me to a sleep lab to get a polysomnogram. The lab techs insisted I try to sleep at midnight, and they woke me at 5 a.m. The sleep doctor then informed me that my problem was I wasn’t getting any deep sleep. No, not between midnight and 5 a.m.—I could have told her that.