It is simple.
Every body movement (jogging, exercise or even walking instead of other kind of transportation) will start your metabolism, release hormons like endorfins to your blood and "pump" your body up. And dancing, because of the rhytm of the music and very positive feeling will do this even faster.

This is why is not recommended to exercise before you are about to go to bed, because you won´t be able to sleep.

I started to walk to work instead of taking bus in the morning and I feel less tired myself.