The numbers on the clock doesn't have any biological significance, that is all in your head. They did however use to tell you what state the sun was in.
The numbers on the clock absolutely do have biological significance, since my biology is influenced by my sleeping and waking times. These are primarily driven by societal expectations (working 9-5, eating dinner between 6-8, etc.), not the state of the sun. As a result, basically no one is awake to appreciate the 'extra' daylight in the early hours of the morning under standard time, but almost everyone can appreciate the 'extra' daylight in the evening under daylight savings time.
It doesn't have biological significance, but it is more convenient to wrap the date when there is the least activity of people (the same reason why we switch DST between 2:00 and 3:00).
