We are still in transition from having the clocks set back an hour on the weekend.  There was no gradual change.  One minute it was one time; next minute it was an hour earlier.  Wow.  What a fascinating experience.

Our bodies continue on the old time for awhile: wonder why we're hungry when the clock says we shouldn't be; wake up before the alarm; deal with darkness when the day before it was still light; have a startle reflex when we come across the clock we forgot to turn back .  And then, marvellous machines, we adjust; adapt our inner timing systems. 

Why do we Fall them back?  Something to do with farmers and livestock pops to mind.