How would you use the word day in a sentence?

Day:
noun:
a. the time of light between one night and the next.
b. a period of 24 hours beginning at midnight.
c. a specified day or date.
d. a specified time or period.
e. the time set apart by custom or law for work.


Example sentences:

1. I sleep during the day and stay up all night.
2. Today is a brand new day.
   
3. The day you were born was the happiest day of my life.
4. Back in the day, it used to be safe to walk the park at night.
   
5. Last week, we worked a 10 hour day shift.