Advanced Sleep Phase Syndrome refers to a condition in which a patient wakes up too early in the morning and gets sleepy early in the evening. It is common in older people.
Other definition:
Advanced Sleep Phase Syndrome (ASPS) refers to phases of the daily sleep/wake cycle are advanced with respect to clock time. This is classified as a circadian rhythm disorder. The sleep phase occurs well ahead of the conventional bedtime and the tendency is to wake up too early.

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