Original: Among people with healthy circadian clocks , there is a continuum of chronotypes from '' larks '' , '' morning people '' , who prefer to sleep and wake early , to '' owls '' , '' evening people '' or '' night people '' , who prefer to sleep and wake at late times .
Simplified: People with this syndrome are sleepy very early in the evening and they sleep from about 19:00 -20:00 in the evening to about 03:00 -04:00 in the early morning .