The Cleveland Clinic offers tips for readjusting an individual’s sleep cycle.

If a person normally sleeps from about 10 p.m. to 6 a.m., advanced sleep disorder would change that so they may fall asleep as early as 6 p.m. and wake up at 2 in the morning. Their total amount of sleep and its quality is normal, as is their function during the day, but their clock shifts backwards.