Final answer:
Advanced Sleep Phase Disorder (ASPD) is a sleep disorder where individuals experience earlier sleep-wake cycles than normal, impacting their adaptability to usual social and work schedules.
Step-by-step explanation:
Advanced Sleep Phase Disorder (ASPD) is answer C: a disorder where sleep-wake cycles are shifted earlier than desired. Many individuals suffer from sleep disorders, including insomnia, parasomnias, sleep apnea, and narcolepsy, impacting their daily lives. ASPD is particularly characterized by a circadian rhythm issue that causes individuals to fall asleep and wake up several hours earlier than the average person, often leading to difficulties in adapting to standard work schedules and social activities.