Delayed sleep phase syndrome (DSPS) is a disorder where
you find it harder to go to sleep until very late at night.
This can be as late as 4AM. In the morning, you will want
to sleep in for longer, perhaps until the early afternoon. If
you have to wake up earlier than this, then you will feel
groggy, but as the day goes on, you will get more energy.
Even if you wake up early, in the evening your body will
still only want to go to sleep late at night.