original_query: What is delayed sleep phase disorder (DSPD)?
query: What is delayed sleep phase disorder (DSPD)?
answer: Delayed sleep phase disorder (DSPD), also known as delayed sleep phase syndrome or delayed sleep–wake phase disorder, is a condition where a person's circadian rhythm (biological clock) is delayed compared to the general population and societal norms. This affects sleep timing, alertness, body temperature, and other daily cycles.  People with DSPD typically fall asleep hours after midnight and struggle to wake up in the morning. It's believed to have a genetic component and may be a lifelong condition.