People with DSPD generally fall asleep some hours after midnight and have difficulty waking up in the morning.
If they are allowed to follow their own schedules, e.g. sleeping from 3:00 am to 12:00 noon, their sleep is improved and they may not experience excessive daytime sleepiness.
People with DSPD have at least a normalāand often much greater than normalāability to sleep during the morning
DSPD patients usually sleep well and regularly when they can follow their own sleep schedule, e.g., on weekends and during vacations.
Often people with DSPD manage only a few hours sleep per night during the working week, then compensate by sleeping until the afternoon on weekends.
Patients have little or no reported difficulty in maintaining sleep once sleep has begun.
Occasional noncircadian days may occur (i.e., sleep is āskippedā for an entire day and night plus some portion of the following day), followed by a sleep period lasting 12 to 18 hours.
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